680931

Lancom DSL 25 Office - ELSA Handleiding

10
Verklein
Vergroot
Pagina terug
1/117
Pagina verder
ELSA LANCOM
TM
DSL/25 Office
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© 2000 ELSA AG, Aachen (Germany)
While the information in this manual has been compiled with great care, it may not be deemed
an assurance of product characteristics. ELSA shall be liable only to the degree specified in the
terms of sale and delivery.
The reproduction and distribution of the documentation and software supplied with this product
and the use of its contents is subject to written authorization from ELSA. We reserve the right to
make any alterations that arise as the result of technical development.
ELSA is DIN EN ISO 9001 certified. The accredited TÜV CERT certification authority has
confirmed ELSA conformity to the worldwide ISO 9001 standard in certificate number 09 100
5069, issued on June 15, 1998.
You can find all declarations and approvals for the products, as long as they were available at the
time of publication, in the appendix of this documentation.
Trademarks
Windows
®
, Windows NT
®
and Microsoft
®
are registered trademarks of Microsoft, Corp.
The ELSA logo is a registered trademark of ELSA AG. All other names mentioned may be
trademarks or registered trademarks of their respective owners.
Subject to change without notice. No liability for technical errors or omissions.
ELSA AG
Sonnenweg 11
52070 Aachen
Germany
www.elsa.com
Aachen, May 2000
20661/0500
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Preface
Thank you for placing your trust in this ELSA product.
By selecting the ELSA LANCOM DSL/25 Office you have chosen a router
which you can use to connect local area networks or single workstations with
other networks via an ATM line. Connection to the ATM network is realized
via a ADSL connection.
Documentation
The accompanying documentation comprises:
Manual
Hardware installation, description of functions and operating modes and
examples of configurations
CD containing electronic documentation
Basic technical information (e.g. on ATM, general network technology,
TCP/IP), workshop with comprehensive usage examples, reference
section with complete menu description
Our online services (www.elsa.com) are available to you around the clock
should you have any queries regarding the topics discussed in this manual or
require any further support. In the Support file section under 'Know-How',
you can find answers to frequently asked questions (FAQs). The
KnowledgeBase also contains a large pool of information. Current drivers,
firmware, tools and manuals can be downloaded at any time.
The KnowledgeBase can also be found on the CD. Just open the file
\Misc\Support\MISC\ELSASIDE\index.htm.
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Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1 What does a router do? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2 What does the ELSA LANCOM DSL/25 Office offer? . . . . . . . . . . . . . . . . . . . . . . . 12
2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1 Package contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 System preconditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3 Setting up the computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.1 Windows 95 and Windows 98 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.2 Windows NT 4.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4 Introducing the ELSA LANCOM DSL/25 Office . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.4.1 The front of the unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.4.2 The back of the unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5 How to connect the device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.6 Software installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.7 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.7.1 Basic settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.7.2 ATM connection setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.7.3 Establishing ATM fixed connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.4 Establishing ATM dial-up connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3 Configuration modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.1 Many paths lead to the ELSA LANCOM DSL/25 Office . . . . . . . . . . . . . . . . . . . . . 33
3.2 The direct method: outband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2.1 Requirements for outband configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.2 Outband configuration using ELSA LANconfig . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.3 Outband configuration using a terminal program. . . . . . . . . . . . . . . . . . . . . . 34
3.3 The user-friendly method: inband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.3.1 Preconditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.3.2 Alternatively: address administration with the DHCP server. . . . . . . . . . . . . 35
3.3.3 Configuration using ELSA LANconfig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.3.4 Configuration using telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.4 Remote access: configuration using a dial-up connection . . . . . . . . . . . . . . . . . . . 37
3.4.1 This is what you need for remote configuration. . . . . . . . . . . . . . . . . . . . . . . 37
3.4.2 This is how you prepare the remote configuration. . . . . . . . . . . . . . . . . . . . . 37
3.4.3 The first remote connection using a dial-up connection (ELSA LANconfig). . 37
3.4.4 The first remote connection using a PPP client and telnet. . . . . . . . . . . . . . . 38
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3.4.5 Limiting remote configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.5 New firmware with FirmSafe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.5.1 This is how FirmSafe works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.5.2 How to load new software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.6 What's happening on the line? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.6.1 ELSA LANmonitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.6.2 Trace outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.6.3 Configuration using SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4 Operating modes and functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1 Security for your configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1.1 Password protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1.2 Login barring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.1.3 Access control via TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.2 Security for your LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.2.1 Security check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.2.2 Checking the number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.2.3 The hiding place—IP masquerading (NAT, PAT) . . . . . . . . . . . . . . . . . . . . . . 51
4.3 Call charge management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.3.1 Limiting the number of online minutes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.3.2 Settings in the charge module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.4 ATM connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.4.1 Connection settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.4.2 Layer list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.4.3 Traffic contracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.4.4 List of fixed connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.4.5 Name list. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.5 Point-to-point protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.5.1 The protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.5.2 The PPP list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.5.3 Everything OK? Checking the line with LCP. . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.6 IPX routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.6.1 IPX addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.6.2 Information on the LAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.6.3 IPX-routing-table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.6.4 What happens during data transfer in the IPX network? . . . . . . . . . . . . . . . . 64
4.6.5 RIP and SAP tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.6.6 There are so many routers here.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.6.7 Redundant routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.6.8 Exponential backoff. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
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4.6.9 IPX packet filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.7 IP routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.7.1 The IP routing table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.7.2 TCP/IP packet filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.7.3 Proxy ARP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.7.4 Local routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.7.5 Dynamic routing with IP RIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
4.7.6 IP masquerading (NAT, PAT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.7.7 DNS forwarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.7.8 Policy-based routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.8 Automatic address administration with DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.8.1 The DHCP server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.8.2 DHCP—'on', 'off' or 'auto'?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.8.3 How are the addresses assigned? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
4.8.4 Configuring the DHCP server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.9 DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.9.1 What does a DNS server do? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.9.2 Setting up the DNS server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.10 NetBIOS proxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.10.1 To the point: What is NetBIOS? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.10.2 Handling of NetBIOS packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.10.3 Which preconditions must be fulfilled? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.10.4 Linking two Windows Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.10.5 Dial-up procedure for a remote access station . . . . . . . . . . . . . . . . . . . . . . 98
4.10.6 Search and find: the Network Neighborhood. . . . . . . . . . . . . . . . . . . . . . . . 99
4.11 ELSA CAPI Faxmodem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.11.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.11.2 Faxing with the ELSA CAPI Faxmodem. . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.12 Office communications and LANCAPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4.12.1 ELSA LANCAPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
5 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.1 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.2 Warranty conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5.3 Declaration of conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Menu reference for ELSA LANCOM DSL/25 Office on CD only
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1 Introduction
The sheer speed of development of computer technology over the last few
years has resulted in a huge increase in the volume of electronic data traffic.
More users every day want to send and receive a constantly increasing
volume of data. Conventional transmission technologies (modem or ISDN
devices) are no longer equal to the demand.
New technologies are eliminating the restrictions and are offering the user
true broadband communications at significantly higher transfer speeds. An
important criterion for the spread of these new access technologies is their
availability in as many offices and companies as possible. One new
technology is transmission by xDSL, which covers the “last mile” over
conventional copper wires. For example, connection to ATM high-speed
networks becomes possible.
The ELSA LANCOM DSL/25 Office gives you a router that has been specially
developed for the ATM interface of xDSL terminals. ELSA LANCOM DSL/25
Office allows connection of individual workstations or entire local networks
and provides considerably higher transmission rates than what was possible
via ISDN.
Special highlights:
Rapid Internet connection. ELSA LANCOM DSL/25 Office allows
transmission rates up to 6 MB/s downstream and 0.6 MB/s upstream in
the ATM network.
LAN connection via ATM or ISDN. ELSA LANCOM DSL/25 Office
supports not only fixed connections but also dial-up connections to
remote stations in the ATM and ISDN network (now in process at several
network operating companies) and thus providing connection of
individual local networks to a common WAN (Wide Area Network).
Office communication via broadband CAPI. With the integrated
broadband CAPI, normal ISDN-CAPI applications such as remote access
or fax can also profit from the available transmission bandwidth.
This section is a brief introduction to the device and its functions. See the
following sections for a detailed description of the functions, the software
and how to use it and an introduction to the technical basics.
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1.1 What does a router do?
A router connects local networks (LANs) and individual PCs to form a Wide
Area Network (WAN). This allows any computer in this WAN to access the
computers and services on the entire network, depending on its access
privileges. The router does this by seeking out a path over which data can be
exchanged between the computers.
This is available in the form of an ATM connection, for example, that can be
realized via normal copper telephone lines with xDSL technology.
Connection to the Internet is a particularly widespread form of network
connection. If the local network in a company is connected with the network
of an Internet service provider, all computers in the LAN will be able to access
the services and sites on the World Wide Web.
But routers are capable of more. Using a special interface called the ELSA
LANCAPI, modern office communications functions such as fax or
EuroFileTransfer etc. can be provided on the entire local network. The
corresponding communications programs forward their data via the LANCAPI
to the router which then takes care of the data transmission. Equipping the
individual workstations with their own data communications equipment—a
costly, high-maintenance scenario—thus becomes superfluous.
The router is incorporated into the network in the same way as any normal
PC. Any data traveling on the network cable, therefore, is seen by the router
too. It automatically determines whether or not the data needs to be
transmitted to another network. If necessary, it establishes the connection
to the destination network. Of course, a dedicated line does away with the
process of establishing a connection.
When precisely should the router be used?
As a matter of fact, wherever computers need to be joined together and a
simple modem operation no longer fits the bill. Here are some example
applications:
Internet on the LAN
Many companies are experiencing an increasing demand for Internet
access from all workstations on the LAN. Online research, file transfer
and e-mail are just some of the applications intended to lighten the
workload of those working at a PC.
The router links all the workstation computers on your local area network
to the global Internet. Security features such as IP masquerading not only
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save you money but also shield your network against access from
outside.
LAN to LAN coupling
When business is going well, the time eventually comes for a sister
company or subsidiary to be established in the global markets. Of course,
the branch office, too, has its own network and must to be kept up-to-
date.
LAN to LAN coupling links the individual LANs to form one large network,
even if this means crossing continents. When connecting via a dial-up
connection, an intelligent line management function together with
sophisticated filter mechanisms keeps connections costs low. Of course,
it is also possible to operate a combination of dedicated lines and dial-up
connections.
Teleworking using remote access
The work of many office workers in modern organizations is less and less
dependent on any definite location—the most important factor here is
unimpaired access to shared and freely available information.
Remote access is the key to this. The router on the local network at the
head office enables colleagues to telecommute from their home offices
and traveling staff to access the office while on the road. The ELSA
LANCOM DSL/25 Office naturally also does everything necessary to
protect the company's data holdings during remote access: the callback
function uses the names and call numbers entered to provide access to
specified users only. And telephone charges are calculated at head
office, simplifying the billing process.
Office communications using LANCAPI
Faxing directly from within applications, voice mail with different
announcements according to the time of day, banking without having to
leave the office: These functions are made possible by using the
LANCAPI.
LANCAPI is a special form of the CAPI 2.0 interface that applications
such as ELSA-RVS-COM or ELSA-ZOC can use to access the router.
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1.2 What does the ELSA LANCOM DSL/25 Office
offer?
The following is an outline of the principal features of the device giving you
a quick overview of its capabilities.
Easy installation
Connect the ELSA LANCOM DSL/25 Office to the power supply.
Establish a link to the LAN.
Inserting the ATM cable.
Switch it on.
Go!
LAN connection
DSL router from ELSA can be connected to a (Fast) Ethernet network using the
10/100Base-T port. The connection automatically determines the speed at
which the local network is running.
WAN connection
The ELSA LANCOM DSL/25 Office can be connected to the ATM interface of
an xDSL connection. In principle, it then has access to all of the functions of
a direct connection into the ATM network.
ELSA LANCOM DSL/25 Office supports not only continuous ready
connections (fixed connections, but also PVC, Permanent Virtual Connection)
as well as dial-up connections (SVC, Switched Virtual Connection).
IP via ATM, Classical IP
ELSA LANCOM DSL/25 Office transmits data of various network protocols
such as IP and IPX via the ATM line. For example, networks of various
locations can be connected via ATM or to the Internet with high bandwidths.
PPP using ATM
ELSA LANCOM DSL/25 Office also transmits PPP via the ATM line.
Therefore, all advantages of PPP connections for data transmission via ATM
are available.
Data compression via Stac
Negotiating and assigning IP addresses via the WAN line.
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Callback functions
Password protection
Subadressing
ELSA LANCOM DSL/25 Office supports subaddressing when transmitting and
evaluating calling numbers. Various devices can also be directly addressed
with connections having only one calling number.
Configuration
Setting up and configuring the device to your specific needs is made quick
and easy in the Windows operating systems by the configuration tool
supplied, ELSA LANconfig.
Users of other operating systems use the HTML-based configuration tool,
Telnet or any other terminal program.
This means that you can access the device from the WAN, from the LAN or
directly via your own configuration interface. TFTP is supported along with
SNMP if configuring from the LAN or WAN.
The integrated Setup Wizards from ELSA LANconfig and HTML configuration
help you get the unit operating in a few steps.
Software update
Your devices have a flash ROM memory to ensure that its software remains
state of the art. This allows new firmware to be loaded onto the device
without the need to open it up.
The current version is always available to you on our online media and can be
loaded via the LAN, the WAN or the configuration interface.
FirmSafe
There is no risk involved with loading the new firmware. The FirmSafe
function enables two firmware files to be managed on one device. If the new
firmware version does not function as desired after the upload you can simply
revert to the previous version.
If an error occurs during the upload (e.g. a transmission error) the functioning
previous version is automatically reactivated.
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Intruder protection
For protection against unauthorized access to the company network, the
router provides not only the simple password protection with authentication
mechanisms in PPP, but also a closed security concept for firewall filters and
IP masquerading. Furthermore, login barring prevents any “brute force
attacks” and denies access to the router after a configurable number of login
attempts using an incorrect password.
Charge monitoring
The charges for ATM connections are calculated by the provider depending
on the time used. To avoid unpleasant surprises at the end of the month, you
can establish the amount of online time for your WAN connection within a
given period (e.g. 600 minutes in 6 days) that will be permitted via the ELSA
LANCOM DSL/25 Office. Depending on the network operating company, cost
information is also transmitted, which can be used for cost protection.
ELSA LANmonitor
Under Windows operating systems, this tool displays the status of the router
on the screen at all times. For each device on the local network, the most
important information are displayed, e.g.:
Name of the remote side
Connection duration and transmission rates
Excerpts of the device statistics (e.g. PPP negotiation data)
Additionally, the software allows you to log and save the messages on the
PC for further processing.
Status displays
LED indicators on the front of your device allow you to monitor the ATM and
Ethernet connection, thus simplifying the process of diagnosing any systems
failures.
Statistics
The comprehensive statistics function lets you keep track of your ELSA
LANCOM DSL/25 Office. These statistics give you all the information you
need on the data packets transferred, for example, so that you can optimize
the configuration of your device.
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DHCP
ELSA routers also incorporate the functions of a DHCP server. Thus you can
define a certain range of IP addresses which the DHCP server then
independently assigns to the individual devices on the local network.
When in automatic mode, the router can also define all addresses on the
network and assign them to the devices connected to the network.
DNS server
The router's DNS server functions allow you to set up links between IP
addresses and names of computers or networks. The correct route can be
directly assigned on queries for known computer names.
The DNS server can also access the name and IP information from the DHCP
server and the NetBIOS module.
The DNS server can also serve as an effective filter for the users in your local
network. Access to specified domains can be denied to individual computers
or complete networks.
ELSA LANCAPI and ELSA CAPI Faxmodem
The main advantages of using LANCAPI are economic. The LANCAPI is a
special type of CAPI 2.0 interface through which various communications
programs (e.g. ELSA-RVS-COM or ELSA-ZOC) via the network can access the
router.
Any workstation which has been integrated into the LAN (Local Area
Network) can use LANCAPI to give unlimited access to office communication
functions such as fax and EuroFileTransfer. All functions are made available
throughout the network without the need to add hardware to the
workstations. This does away with the cost of equipping workstations with
ATM adapters. The office communications software simply needs to be
loaded onto the individual workstations.
An fax device is simulated at the workstation so that faxes can be sent. With
the LANCAPI, the PC forwards the fax via the network to the router which
establishes the connection to the recipient.
Line connection and management
The router checks all data on the network to determine whether they have to
be sent to another network or computer. Is data transfer is necessary, the
router establishes the connection itself and closes the connection once the
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transfer is complete. Any partly used call charge units are used up fully if call
charge information is transmitted during the connection.
To reduce transfer costs, the router offers various filter options depending on
the mode of operation. They can be used to exclude from the transfer data
that come from the entire network or from parts of the network. Similarly,
data that belong to specific services (such as printing services) can be filtered
out of the transfer.
NetBIOS proxy
ELSA routers offer a special feature for the interconnection of Microsoft peer-
to-peer networks. With the integrated routing of IP NetBIOS packets, the
linking of Windows networks becomes child's play. The remote stations
relevant for the exchange of data are entered in a list to ensure that not every
NetBIOS packet results in the establishment of a connection.
As a NetBIOS proxy, the router answers the queries for known workstations
locally to prevent connections from being established unnecessarily.
Compatibility through PPP
The router uses PPP, a widely used protocol, and other protocols to exchange
network data through point-to-point connections with devices made by other
manufacturers.
Remote configuration using PPP
One special configuration feature of the routers from ELSA which cannot and
should not be setup locally is its ability to be configured remotely via PPP
connections and the Windows Dial-up Network. All you have to do is to plug
the new device into the power supply and connect it to the WAN Basic Rate
Interface. Now you can access the router using a PPP connection and
configure it from your location. The first time the device is configured, access
to it is secured by a password and thereafter it remains inaccessible to
unauthorized callers.
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2 Installation
This section will help you connect to the Internet as quickly as possible. You
will first find out what your product includes and get to know it. Then we will
show you how to connect the device and get it working.
The following information is intended for experienced users familiar with
hardware and network configuration.
2.1 Package contents
Please check the package contents for completeness before starting the
installation. The following components should be in the box:
ELSA LANCOM DSL/25 Office
Power supply unit
LAN connection cable
ATM connection cable
Cable for the configuration interface
Adapter for configuration cable
Documentation
CD containing ELSA LANconfig, other software and electronic
documentation
Please contact your dealer directly if anything is missing.
2.2 System preconditions
The system that you want to connect to the Internet with the unit must meet
the following requirements:
Any operating system that supports the TCP/IP network protocol, such as
Windows 95, Windows 98, Windows 2000, Windows NT 4.0, OS/2, Linux
or BeOS
Windows 95, Windows 98, Windows 2000 or Windows NT 4.0 and a CD-
ROM drive for those computers on which you want to install the ELSA
LANconfig configuration software
Ethernet network card
Network protocol TCP/IP installed and bound to the network card
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2.3 Setting up the computer
Routers from ELSA make it extremely simple to manage addresses on local
networks. A few settings might have to be made at the workstations to
ensure that the routers and workstation communicate together properly.
2.3.1 Windows 95 and Windows 98
Using Windows 95 and Windows 98 as examples, this section will show
what needs to be done, if it is not already done for you, to ensure smooth
communication between computers in a TCP/IP network with the router
connected to the workstations.
Installing TCP/IP
To install TCP/IP, click Start Settings Control Panel Network
Add... Protocol. Select the manufacturer 'Microsoft' and the 'TCP/
IP' network protocol.
Allocate IP addresses (using DHCP)
If you are going to use the router as a DHCP server, set the workstations
to obtain IP addresses automatically: Start Settings Control
Panel Network TCP/IP Properties IP Address Obtain
an IP address automaticaly. Also, delete any existing entries for DNS
servers and gateways (found under the 'Gateway' and 'DNS
Configuration' tabs). When the computer is restarted, it then searches for
a DHCP server on the network and lets it assign an IP address to it.
Setting fixed IP addresses (not using DHCP)
If you are not going to use a DHCP server on your network, assign the
workstations fixed IP addresses: Start Settings Control Panel
Network TCP/IP Properties IP Address Specify an IP
address.
Assign unique IP addresses, for example taken from a reserved range of
addresses. For example, the workstations can be assigned addressed
from '10.1.1.2' to '10.1.1.253', the router can be given '10.1.1.1' and all
can have the subnet mask of '255.255.255.0'. To test whether or not a
specific IP address, such as '10.1.1.1', is free, enter
ping 10.1.1.1
in a DOS session. If you do not receive a response, the address is most
likely free.
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Entering the Gateway and DNS Server (not necessary when using DHCP)
On the workstation computers, specify the address of the local network
router as the Gateway and as the Domain Name Server (DNS server):
Start Settings Control Panel Network TCP/IP
Properties Gateway and DNS Configuration. Also enter a host
name on the DNS Configuration page. In doing so, use the name of the
PC, which ideally matches the user's name, to maintain a certain amount
of consistency.
Checking the IP configuration
Under Windows 95 and Windows 98, you can view the current IP
configuration of your computer with by using Start Run...
winipcfg. Among other information, this shows you which IP address
was assigned to the computer by the DHCP server and which addresses
have been specified for DNS servers and the gateway.
2.3.2 Windows NT 4.0
Using Windows NT 4.0 as an example, this section will show what needs to
be done, if it is not already done for you, to ensure smooth communication
between computers in a TCP/IP network with the router connected to the
workstations.
Installing TCP/IP
To install TCP/IP, click Start Settings Control Panel Network
Protocols Add.... Select the 'TCP/IP protocol' network protocol.
Allocate IP addresses (using DHCP)
If you are going to use the router as a DHCP server, set the workstations
to obtain IP addresses automatically. To do so, select Yes when
completing the network protocol installation.
Windows then copies the required files and, when finished, requests you
to reboot.
Setting fixed IP addresses (not using DHCP)
If you are not going to use a DHCP server on your network, assign the
workstations fixed IP addresses: Start Settings Control Panel
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Network Protocols Properties.... This page also lets you set the
standard gateway.
Assign unique IP addresses, for example taken from a reserved range of
addresses. For example, the workstations can be assigned addressed
from '10.1.1.2' to '10.1.1.253', the router can be given '10.1.1.1' and all
can have the subnet mask of '255.255.255.0'. To test whether or not a
specific IP address, such as '10.1.1.1', is free, enter
ping 10.1.1.1
in a DOS session. If you do not receive a response, the address is most
likely free.
Entering the DNS server (not necessary when using DHCP)
On the workstation computers, specify the address of the local network
router as the Domain Name Server (DNS server) on the on the 'DNS'
page. Also enter a host name on the DNS configuration page. In doing
so, use the name of the PC, which ideally matches the user's name, to
maintain a certain amount of consistency.
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Checking the IP configuration
Under Windows NT 4.0 you can querry the current IP configuration of your
computer with Start Run... ipconfig. This shows you which IP
address was assigned to the computer by the DHCP server and which
addresses have been specified for the gateway (not for the DNS server).
2.4 Introducing the ELSA LANCOM DSL/25 Office
This section introduces the unit's hardware. It covers the unit's display
elements and connection options.
2.4.1 The front of the unit
You will find a number of LEDs as display elements on the front panel.
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Power/Msg
This LED flashes once when the power supply is switched on. After the self-
test, either an error is output by a flashing light code or the device starts and
the LED remains lit.
ATM status
This LED shows the status of the ATM connection to the switching center:
ATM-rx
ATM-tx
This LEDs show that data is moving on the ATM connection:
LAN-tx, -rx,
LAN-coll, -link
LAN-FDpx, -Fast
These LEDs show the corresponding network controller status:
2.4.2 The back of the unit
Now turn the whole thing around and take a look at the rear. Beginning again
on the left-hand side, you have:
Off Device off
red 1 x short Boot procedure (test and load) started
red flashing Display of a boot error (flashing light code)
red Device ready for use
Off No signal from the ATM switching center
flashing Signal of the switching center is active, but no valid connection to the
switching center is established.
on At least one valid connection is established
ATM-rx green Data packet received from the ATM switching center
ATM-tx yellow Data packet sent from the device to the ATM switching center
LAN-rx/tx yellow Data packet sent from the device to the LAN or vice versa
LAN-coll red Sending collision
LAN-link green Connection to LAN is established and ready
LAN-FDpx green Router is transmitting and receiving data simultaneously
LAN-fast green ELSA LANCOM DSL/25 Office is operating at 100 Mbit
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On/Off switch
Connection for power supply unit
10/100Base-Tx for 10 Mbit or 100 Mbit networks
Node/hub selector switch
V.24 configuration interface
ATM-25.6 connection
2.5 How to connect the device
Connect your ELSA LANCOM DSL/25 Office to the LAN. Plug the network
cable (supplied) into the 10/100Base-TX terminal of the device and into a
free network connector on your local network (or into a free socket on a
hub in your LAN).
Connect your ELSA LANCOM DSL/25 Office to the ATM network. Plug
the ATM connection cable provided in the ATM-25.6 connection of the
device and in the Ethernet interface of the NTBBA.
Connect the AC adapter to the device and switch it on. After a short
device self-test the 'Power/Msg' LED will be permanently lit. The 'LAN
Link' LED indicates that your router is correctly connected to the LAN.
If this LED does not come on, reverse the node/hub selector switch. If the LED
still does not light, there may be a problem with the network card or the
wiring.

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2.6 Software installation
The ELSA LANconfig configuration software for Windows operating systems
enable you to set up your router easily and conveniently for the desired
application.
You will need a Windows PC on the LAN to run ELSA LANconfig.
Install the TCP/IP network protocol on the computer that will be used to
set up your device.
Then install ELSA LANconfig. If the setup program does not start up
automatically after insertion of the ELSA LANCOM CD, start Windows
Explorer, click on 'autorun.exe' on the ELSA LANCOM CD and follow the
instructions in the install program.
2.7 Configuration
Configure the unit using the following steps:
Basic settings
ATM connection setting
Router configuration
There is an information table for each of the stages of configuration, which
describes the information you will have to have available. Fill out the tables
before starting the process of configuration.
2.7.1 Basic settings
With the basic settings, you assign a name to the unit and define the IP
addresses for operation in the local network. In this example, the DHCP
server in the router automatically takes over the task of assigning IP
addresses.
ELSA LANconfig
The first time ELSA LANconfig is run, the new device is detected on the TCP/
IP network and can immediately be configured. A wizard is automatically
started to help you with the basic settings of the device or it can even the
complete setup itself.
Start the new software with Start Programs ELSAlan ELSA
LANconfig.
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Select the option 'All settings to be defined automatically' if you are not
familiar with networks and IP addresses and one of the following
conditions applies:
You have not used any IP addresses previously in your network but
would now like to do so. You do not care which IP address should be
used. The router as a DHCP-server will automatically set and assign
the IP addresses for all devices in the network (LAN and WLAN).
or
You do not wish to use IP addresses, perhaps because you have a
Windows-only network.
If you do not know whether IP addresses have been used in your network, first
click on Start Run..., enter the following command in the window
winipcfg and click OK. If the next window shows the value '0.0.0.0' in the
field 'IP address', the computer has never had an IP address.
Select the option 'I wish to define the settings myself' if you are familiar
with networks and IP addresses and one of the following conditions
applies:
You have not used any IP addresses previously in your network but
would now like to do so. However, you wish to set the IP address for
the router and assign it an address from an address range reserved
for private use, e.g. '10.0.0.1' with the network mask '255.255.255.0'.
At the same time you will set the address range that the DHCP server
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uses for the other devices in the network (so long as the DHCP server
is not switched off).
You have previously used IP addresses on the computers in the LAN.
Assign the router a free address from the previously used address
range, and select whether the router should run as a DHCP server or
not.
You can find more information on the general structure of networks and
setting IP addresses in the electronic documentation on the ELSA LANCOM
CD. The functions of the DHCP server are described later in this manual.
Telnet
Start the telnet connection to the address '10.0.0.254' if you have not
previously used IP addresses in your network, or to address 'x.x.x.254', where
'x.x.x' stands for the address group previously used in the network.
Enter the following command:
You can start the telnet connection with the command Start Run...
and entering the command
telnet 10.0.0.254 in the window.
Change the language for the configuration with the command:
set /Setup/config-module/language english
Intranet address and network mask:
set /setup/TCP-IP-module/Intranet addr. 10.0.0.1
set /setup/TCP-IP-module/Intranet-mask
255.255.255.0
When the internet address is changed, the telnet connection is interrupted.
To switch off the DHCP function:
set setup/DHCP-module/operating off
Even if the entries at this point are not very clear without further explanation,
you can reach the same destination as with the setup with ELSA LANconfig.
With these settings, you have completed making your new router known on
the local network. The router itself is addressable using the IP address of
'10.0.0.1'. After you reboot your system, all units on the local network will be
assigned IP addresses by the DHCP server in the router. It will use an address
pool from '10.0.0.2' to '10.0.0.253' automatically.
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2.7.2 ATM connection setting
Enter the values for your ATM connection and the connections to other
devices. Some of these values are provided by your telephone company.
Which type of information do you need?
Setting with ELSA LANconfig or telnet
Start up ELSA LANconfig from the program group 'ELSAlan'. ELSA
LANconfig automatically searches for new devices in the local network
and on the configuration interface.
Alternatively, establish a connection to your new device with telnet. For
example, enter the following command when prompted:
telnet 10.0.0.1
Open the configuration dialog box by clicking on the corresponding entry
in the device list.
Go to the 'Interfaces' register card and open the list of interface
settings. For the ATM interface, indicate the protocol for the
signalization channel , a dialing prefix if necessary, the number of
the virtual connection path (VPI ), the physical speed of the connection
(LCR ), and the traffic contract for the signalization channel .
Protocol for the signalization channel
Dialing prefix (required only for ATM-TK
installations and private networks)
Virtual Path Identifier (VPI)
Link Cell Rate (LCR) for the ATM connection
(upstream)
Traffic contract for signalization channel
Calling number(s) for ATM interface
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set Setup/WAN-module/ ATM-1 UNI3.1 1368 0 0
SIGNALING-interface-list
The traffic contract established here refers exclusively to the signalization
channel during dial-up connections. This setting does not effect the data
transmission channels! Traffic contracts can be established in the
'Communication' configuration area on the 'General' register card or via
telnet under
/Setup/WAN-module/Traffic-contracts.
Go to the 'General' register card in the 'Communcation' configuration
area and open the settings for the ATM interface under 'Router
interfaces'. Enter the calling number(s) to which the router should
respond. The first calling number entered is used for outgoing calls. In
addition, select whether the custom calling number should be displayed
at the remote station.
The calling numbers in the ATM network are always entered in the complete
international format without the beginning zeros!
set /Setup/WAN-module/Router-interface-list ATM-
1 492416069999 On
After the general settings have been carried out, connections can be
established to the desired remote stations.
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2.7.3 Establishing ATM fixed connection
A fixed connection via the ATM network is configured by simply assigning a
remote station name to a VCI
Which type of information do you need?
Setting with ELSA LANconfig or telnet
Open the configuration, then go to the 'Remote sites' register card and
open the name list. Enter the name of the remote station and select
the layer name and the traffic contract for this connection.
set/Setup/WAN-modulel/BERLIN***LLCPPP
DEFAULT name-list
Go to the 'Remote sites' register card and open the list of fixed
connections. Select the remote station to which you would like to
define the fixed connection , and indicate the number of the virtual
connection channel (VCI) .
Name of the remote station
WAN-layer
Traffic-contract
Virtual Channel Identifier (VCI)
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set /Setup/WAN-module/ BERLIN 101 fixed
connection
That's it! All data packets, which are assigned to the 'Berlin' remote station
using the settings in the routing table, use the fixed connection over the
virtual '101' connection channel.
2.7.4 Establishing ATM dial-up connection
A dial-up connection via the ATM network is configured by a traffic contract
agreement and by assigning a calling number to a remote station name.
Which type of information do you need?
Setting with ELSA LANconfig or telnet
Open the configuration, then go to the 'Communication' register card and
open the list of traffic contracts. Enter a name for the traffic contract
and select the type of traffic contract (variable, non-fixed or constant
bit rate or ISDN for remote stations in the ISDN network). Set the value
for the quality of service and then enter the values for the mid-range
Name for the traffic contract
Traffic type
QoS
Sustainable Cell Rate (Tx/Rx)
Peak Cell Rate (Tx/Rx)
Maximum Burst Size (Tx/Rx)
Name of the remote station
Remote station call number
WAN-layer
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and maximum cell rate as well as the maximum burst length for
sending and receiving data.
set /Setup/WAN-module/Traffic-contracts
Traffic_1 VBR.1 2 300 300 800 800 20 20
Open the register card 'Remote sites' and open the Name list. Enter the
name of the remote station and the calling number select the layer
name and the traffic contract for this connection.
set /Setup/WAN-module/Name list DRESDEN
49241123456**PPPTRAFFIC_1
That's it! All data packets, which are assigned to the 'Dresden' remote
station using the settings in the routing table, use the dial-up connection with
the 'Traffic_1' traffic contract.
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3 Configuration modes
ELSA routers are always dispatched with up-to-date software in which
several of the settings have already been made.
It will nevertheless be necessary for you to add some information and
configure the router to your specific needs. These settings are made as part
of the configuration process.
This section will show you the programs and routes you can use to access the
device and set it up.
And, if the team at ELSA has produced new firmware with new features for
your use, we will show you how to load the new software.
3.1 Many paths lead to the ELSA LANCOM DSL/25
Office
In principle, there are different methods of accessing the router of ELSA:
Through the configuration interface (config interface) on the rear of the
router (also known as outband)
Through the LAN or WAN network (inband)
What is the difference between these?
On one hand, the availability of the units: Configuration via outband is always
available. Inband configuration is not possible, however, in the event of a
network fault.
On the other hand, whether or not you will need additional software or
hardware. The inband configuration requires one of the computers already
available in the LAN or WAN, as well as suitable software. In addition to the
software, the outband configuration also requires one of the computers (with
a serial port) and a suitable configuration cable.
3.2 The direct method: outband
Outband configuration gives you direct access to the router via the
configuration interface.
You really only need to use the outband configuration method if you cannot
access your device via TCP/IP.
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3.2.1 Requirements for outband configuration
What’s needed?
A computer running Windows 95, Windows 98 or Windows NT 4.0 and
ELSA LANconfig.
or
a computer using any operating system and a terminal program (e.g. Telix
or Hyperterminal).
The configuration cable supplied and, if necessary, the 9/25-pin adapter
used to connect the computer and the router (the PCs COM port to the
router's configuration interface).
3.2.2 Outband configuration using ELSA LANconfig
Start up ELSA LANconfig from the Windows Start menu, for instance, by
clicking Start Programs ELSAlan ELSA LANconfig. ELSA
LANconfig will now automatically search for ELSA LANCOM DSL/25 Office
devices in the local area network (but not on the serial ports). New devices
can be found with Device Find Search all ports. ELSA LANconfig
displays new routers in the list by their devices types.
Double-clicking on a device designation in the list of found devices opens the
current configuration for editing.
3.2.3 Outband configuration using a terminal program
After starting the terminal program, press return just a few times to
automatically detect the bit rate (up to 230 kbps, 38.4 kbps as standard).
Once you have entered the password, configuration can be carried out using
any of the commands contained in section 'Configuration commands'.
3.3 The user-friendly method: inband
Using inband configuration allows any computer on the WAN or LAN to
access the router. However, access can be restricted or blocked altogether
using the IP access list. This configuration requires the use of either telnet
(supplied with most operating systems) or ELSA LANconfig for Windows.
ELSA LANconfig is supplied with your device. You can always obtain up-to-
date releases from our online media.
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3.3.1 Preconditions
TCP/IP or TFTP are used to make configurations using telnet or ELSA
LANconfig. This means that the TCP/IP protocol must be installed on the
computer being used and the router must be given an IP address which you
will then use when addressing it.
A device that has not been configured yet will respond to the IP address
XXX.XXX.XXX.254, in which the Xs are placeholders for the network address
in your LAN. If the computers on your network have addresses such as
192.168.130.1, then you will be able to address the device using
192.168.130.254.
If there is already a computer with the address XXX.XXX.XXX.254 on your
network you should assign a new address to the device using the outband
configuration method before you install it on the LAN.
3.3.2 Alternatively: address administration with the DHCP
server
If it is not absolutely essential that you configure the correct IP addresses
“manually”, the DHCP server will gladly do this task for you automatically.
When using the DHCP server you can have the IP addresses for all computers
on the network assigned automatically (see also chapter 'Automatic Address
Administration with DHCP'). The router can also establish its own IP address
on the LAN.
3.3.3 Configuration using ELSA LANconfig
Start ELSA LANconfig e.g. via the Windows taskbar with Start Programs
ELSAlan ELSA LANconfig. ELSA LANconfig searches the local area
network for devices.
Just click on the Find button or call up the command with Device Find to
initiate a search for a new device manually. ELSA LANconfig will then
prompt for a location to search. You will only need to specify the local area
network if using the inband solution, and then you're off.
Once ELSA LANconfig has finished its search, it displays a list of all the
devices it has found, together with their names and, perhaps a description,
the IP address and its status.
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Two different display options can be selected for configuring the devices with
ELSA LANconfig:
The 'simple configuration' display shows only the settings required for
standard cases.
The 'complete configuration' display shows all available settings. Some
of them should only be modified by experienced users.
Select the display mode in the View Options... menu.
Double-clicking the entry for the highlighted device and then clicking the
Configure button or the Edit Edit Configuration File option reads the
device's current settings and displays the 'General' configuration selection.
The remainder of the program's operation is pretty much self-explanatory or
you can use the online help. You can click on the question mark top right in
any window or right-click on an unclear term at any time to call up context-
sensitive help.
3.3.4 Configuration using telnet
Start up the configuration (e.g. from a DOS box) using telnet with the
command:
telnet 10.1.80.125
Telnet will then establish a connection with the device using the IP address.
After entering the password (if you have set one to protect the configuration),
all commands are available from the 'Configuration commands' section.
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3.4 Remote access: configuration using a dial-up
connection
Configuring routers at remote sites is particularly easy using the remote
configuration method via a Dial-up connection. The device is accessible by
the administrator immediately without any settings being made after it is
switched on and connected to the WAN interface. This means that you save
a lot of time and costs when connecting other networks to your network
because you do not have to travel to the other network or instruct the staff
on-site on configuring the router.
You can also reserve a special calling number for remote configuration. Then
the support technician can always access the router even if it is really no
longer accessible due to incorrect settings.
3.4.1 This is what you need for remote configuration
A computer with a PPP client, e.g. Windows Dial-up Networking
A program for inband configuration, e.g. ELSA LANconfig or telnet
An ATM card or a ELSA LANCOM DSL/25 Office with ELSA LANCAPI
3.4.2 This is how you prepare the remote configuration
Attach the router to the power supply.
Connect the device to a WAN basic rate interface.
3.4.3 The first remote connection using a dial-up connection
(ELSA LANconfig)
In the ELSA LANconfig program select Device New, enable 'Dial-up
connection' as the connection type and enter the calling number of the
WAN interface to which the ELSA LANCOM DSL/25 Office is connected.
If you wish, you can also enter the time period after which an idle
connection is to be disconnected automatically.
ELSA LANconfig now automatically generates a new entry under Dial-up
Networking. Select a device that supports PPP (e.g. the NDIS WAN driver
included with the LANCAPI) for the connection and press OK to confirm.
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Then the ELSA LANconfig program will display a new device with the
name 'Unknown' and the dial-up call number as the address in the device
list.
Once the entry appears in the device list the Dial-up Networking connection
is broken.
You can configure the device remotely just like all other devices. ELSA
LANconfig establishes a dial-up connection enabling you to select a
configuration.
3.4.4 The first remote connection using a PPP client and telnet
Establish a connection to the ELSA LANCOM DSL/25 Office with your PPP
client using the following details:
User name 'ADMIN'
Password as set on the ELSA LANCOM DSL/25 Office, factory default
setting is no password
An IP address for the connection, only if required
Open a telnet session to the ELSA LANCOM DSL/25 Office. Use the
following IP address for this purpose:
'172.17.17.18', if you have not defined an IP address for the PPP
client. The ELSA LANCOM DSL/25 Office automatically uses this
address if no other address has been defined. The calling PC then
responds to the IP address '172.17.17.17'.
Raise the IP address of the PC by one, if you have defined an address.
For example: If you have defined the IP address '10.0.200.123' for the
PPP client, the ELSA LANCOM DSL/25 Office will respond to
'10.0.200.124'. Exception: If the digits '254' are at the end of the IP
address, the router responds to 'x.x.x.1'.
You can configure the ELSA LANCOM DSL/25 Office remotely just like all
other devices.
3.4.5 Limiting remote configuration
The PPP connection of any other remote site to the router, of course, will only
succeed if the device answers every call with the corresponding PPP settings.
This is the case using the factory default settings because the default
protocol (default layer) is set to PPP.
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You may, however, want to change the default layer for LAN-to-LAN
connections, for example, to a different protocol after the first configuration
run. Then the device will no longer take calls on the dial-up connection using
the PPP settings. The solution to this is to agree upon a special calling
number for configuration access. If the device receives a call on this number,
it will always use PPP, regardless of any other settings made on the router.
Only a specific user name which is automatically entered by the ELSA
LANconfig program during call establishment will be accepted during the PPP
negotiations.
Switch to the 'Security' tab in the 'Management' configuration section.
In the 'Configuration access' field, choose whether the configuration is
fully accessible, read-only or not accessible from remote networks.
Alternatively, enter the following command during a telnet or terminal
connection:
set /setup/config-module/WAN-config
[on][read][off]
If you wish to block access to the router from the WAN entirely, set
configuration access from remote networks to 'denied'.
In the 'Configuration access' field, enter a calling number of your
connection which is not used for other purposes as the calling number.
Alternatively, enter the following command:
set /setup/config-module/Farconfig 123456
You can protect the configuration of the device by assigning a password.
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Alternatively, enter the following command:
passwd
You will then be prompted to enter and confirm a new password.
3.5 New firmware with FirmSafe
The software for the ELSA devices is constantly being updated. We have
fitted the devices with a flash ROM which makes child's play of updating the
operating software so that you can enjoy the benefits of new features and
functions. No need to change the EPROM, no need to open up the case:
simply load the new release and you're away.
3.5.1 This is how FirmSafe works
FirmSafe makes the installation of the new software safe: The used firmware
is not simply overwritten but saved additionally in the device as a second
firmware.
Of the two firmware versions saved in the device only one can ever be active.
When loading a new firmware version the active firmware version is not
overwritten. You can decide which firmware version you want to activate
after the upload:
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'Immediate': The first option loads the new firmware and activates it
immediately. This can result in the following situations:
The new firmware is loaded successfully and works as desired. Then
all is well.
The device no longer responds after loading the new firmware. If an
error occurs during the upload, the device automatically reactivates
the previous firmware version and reboots.
'Login': To avoid problems with faulty uploads there is the second option
with which the firmware is uploaded and also immediately booted.
In contrast to the first option, the device will wait for five minutes
until it has successfully logged on. Only if this login attempt is
successful does the new firmware remain active permanently.
If the device no longer responds and it is therefore impossible to log
in, the firmware automatically loads the previous firmware version
and reboots with it.
'Manual': With the third option you can define a time period during which
you want to test the new firmware yourself. The device will start with
the new firmware and wait for the preset period until the loaded
firmware is manually activated and therefore becomes permanently
effective.
3.5.2 How to load new software
There are various ways of carrying out a firmware upload (which is the term
given to the installation of software), all of which produce the same result:
ELSA LANconfig (recommended)
Terminal programs
TFTP
All settings will remain unchanged by a firmware upload. All the same you
should save the configuration first for safety's sake (with Edit Save
Configuration to File if using ELSA LANconfig, for example).
If the newly installed release contains parameters which are not present in
the device's current firmware, the device will add the missing values using
the default settings.
ELSA LANconfig
When using ELSA LANconfig, highlight the desired device in the selection list
and click on Edit Firmware Management Upload New Firmware,
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or click directly on the Firmware Upload button. Then select the directory
in which the new version is located and mark the corresponding file.
ELSA LANconfig then tells you the version number and the date of the
firmware in the description and offers to upload the file. The firmware you
already have installed will be replaced by the selected release by clicking
Open.
You also have to decide whether the firmware should be permanently
activated immediately after loading or set a testing period during which you
will activate the firmware yourself. To activate the firmware during the set
test period, click on Edit Firmware Management Upload New
Firmware After upload, start the new firmware in test mode.
Terminal program (e.g. Telix or Hyperterminal in Windows)
If using a terminal program, you should first select the 'set mode-firmsafe'
command on the 'Firmware' menu and select the mode in which you want the
new firmware to be loaded (immediately, login or manually). If desired, you
can also set the time period of the firmware test under 'set Timeout-firmsafe'.
Select the 'Firmware-upload' command to prepare the router to receive the
upload. Now begin the upload procedure from your terminal program:
If you are using Telix, click on the Upload button, specify 'XModem' for
the transfer and select the desired file for the upload.
If you are using Hyperterminal, click on Transfer Send File, select the
file, specify 'XModem' as the protocol and start the transfer with OK.
TFTP
With TFTP you can use the writeflash command to install new firmware. To
transmit a new firmware version to a device with the IP address
194.162.200.17, you would enter the following command under Windows NT
for example:
tftp -i 194.162.200.17 put lcdsl25u.160 writeflash
This command sends the corresponding file to the input IP address using the
writeflash command. Binary file transfer must be set for TFTP. However,
many systems have the ASCII format preset. This example for Windows NT
shows you how to achieve this by using the '-i' parameter.
The device is booted up following a successful firmware upload and this
activates the new firmware switch directly. If an error occurs during the
upload (write error in the flash ROM, TFTP transmission error or similar)
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FirmSafe activates the previous firmware. The configuration connection
remains in operation.
With TFTP, other configuration commands can be performed too. The syntax
is best demonstrated with the following examples:
tftp 10.0.0.1 get readconfig file1: Reads the configuration from the device
with the address 10.0.0.1 and saves it as file1 in the current directory.
tftp 10.0.0.1 put file1 writeconfig: Writes the configuration from file1 to
the device with the address 10.0.0.1.
tftp 10.0.0.1 get dir/status/verb file2: Saves the current connection
information in file2.
3.6 What's happening on the line?
After the basic setup of the devices, further important information can be
gained with regard to the parameters still to be modified, especially by
observing the data flow on the various ports of the router.
In addition to the device statistics that can be read out during a telnet or
terminal session, a variety of other options are also available.
3.6.1 ELSA LANmonitor
The ELSA LANmonitor includes a monitoring tool with which you can view the
most important information on the status of your router on your monitor at
any time under Windows operating systems. Many of the internal messages
generated by the device are converted to plain text, thereby helping you to
troubleshoot.
Installing ELSA LANmonitor
Usually, ELSA LANmonitor is automatically installed together with ELSA
LANconfig on the computer from which you wish to configure your router.
If ELSA LANmonitor is not yet installed on your computer, place the ELSA
LANCOM in your CD drive. If the setup program does not start up
automatically after insertion of the CD, start Windows Explorer, click on
'autorun.exe' on the CD ELSA LANCOM and follow the instructions in the
install program.
During the installation you should activate the 'LANmonitor'.
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With ELSA LANmonitor you can only monitor those devices that you can
access inband via the local network. Your computer must also have the TCP/
IP network protocol installed on it. With this program you cannot access any
router connected to the serial interface.
Checking your connection with ELSA LANmonitor
Start up ELSA LANmonitor by clicking Start Programs ELSAlan
LANmonitor. Generate a new device by selecting Device New and,
in the following window, enter the IP address of the router you wish to
monitor. If the configuration of the device is protected by password,
enter the password too.
Alternatively, you can select the device via the ELSA LANconfig and
monitor it using Options Monitor Device.
ELSA LANmonitor automatically creates a new entry in the device list and
initially displays the status of the transfer channels. As soon as the
connection is established, a plus sign indicates that further information
on this channel is available. Click on the plus sign to open a tree structure
in which you can view various information.
3.6.2 Trace outputs
Trace outputs may be used to monitor the internal processes in the router
during or after configuration. One such trace can be used to display the
individual steps involved in negotiating the PPP. Experienced users may
interpret these outputs to trace any errors occurring in the establishment of
a connection. A particular advantage of this is: The errors being tracked may
stem from the configuration of your own router or that of the remote site.
The trace outputs are slightly delayed behind the actual event, but are always
in the correct sequence. This will not usually hamper interpretation of the
displays but should be taken into consideration if making precise analyses.
How to start a trace
The command to call up a trace follows this syntax:
trace [code] [parameters]
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The trace command, the code, the parameters and the combination
commands are all separated from each other by spaces. And what is lurking
behind the code and parameters?
This code ... ... in combination with the trace causes the following:
? Displays a help text
+ Switches on a trace output
- Switches off a trace output
# Switches between different trace outputs (toggle)
no code Displays the current status of the trace
This parameter ... ... brings up the following display for the trace:
Status Status messages for the connection
Error Error messages for the connection
PPP PPP protocol negotiation
IP router IP routing
IP RIP IP Routing Information Protocol
ICMP Internet Control Message Protocol
ARP Address Resolution Protocol
IP-masquerading Processes in the masquerading module
DHCP Dynamic Host Configuration Protocol
ATM Displays defective cells as well as cells which cannot be assigned
to a logical connection.
OAM-cells Displays OAM-cells.
AAL5-frames Displays the beginning and end of a AAL5-frame.
SSCOP ATM security protocol
SAAL Displays AAL5-frames of the signalization layer.
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Any appended parameters are processed from left to right. This means that
it is possible to call a parameter and then restrict it.
Examples
3.6.3 Configuration using SNMP
The Simple Network Management Protocol (SNMP V.1 as specified in RFC
1157) allows monitoring and configuration of the devices on a network from
a single central instance.
Detailed information on the configuration of ELSA devices with SNMP can be
found in the electronic documentation on the CD.
This combination
command
... brings up the following display for the trace:
All All trace outputs
Display Status and error outputs
Protocol ELSA and PPP outputs
TCP-IP IP-Rt., IP-RIP, ICMP and ARP outputs
Time Displays the system time in front of the actual trace output.
Source Includes a display of the protocol that has initiated the output in
front of the trace.
This code ... ... in combination with the trace causes the following:
trace Displays all protocols that can generate outputs during the
configuration, and the status of each output (ON or OFF).
trace + all Switches on all trace outputs.
trace + protocol dis-
play
Switches on the output for all connection protocols together with
the status and error messages.
trace + all - icmp Switches on all trace outputs with the exception of the ICMP
protocol.
trace ppp Displays the status of the PPP.
trace - time Switches off the system time output before the actual trace
output.
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4 Operating modes and functions
This section is an introduction to the functions and operating modes of your
device. It includes information on the following points:
Security for your configuration
Security for your LAN
ATM connections
PPP support
IPX routing
IP routing
Automatic address administration with DHCP
DNS server
NetBIOS proxy
Alongside the description of the individual points, we will also give you
instructions to support you as you configure your device.
Please refer to the electronic documentation for a detailed description of all
parameters and menus.
4.1 Security for your configuration
A number of important parameters for the exchange of data are established
in the configuration of the device. These include the security of your network,
monitoring of costs and the authorizations for the individual network users.
Needless to say, the parameters that you have set should not be modified by
unauthorized persons. The ELSA LANCOM DSL/25 Office thus offers a
variety of options to protect the configuration.
4.1.1 Password protection
The simplest option for the protection of the configuration is the
establishment of a password. As long as a password hasn't been set, anyone
can change the configuration of the device.
The password input field can be found in the ELSA LANconfig in the
'Management' configuration section on the 'Security' tab. The password
prompt can be activated in a terminal or telnet session in the
/Setup/Config-module/passw.prompt menu. In this case, the
password itself is set with the command
passwd.
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4.1.2 Login barring
The configuration in the ELSA LANCOM DSL/25 Office is protected against
“brute force attacks” by barring logins. A brute-force attack is the attempt of
an unauthorized person to crack a password to gain access to a network, a
computer or another device. In order to do so, a computer can, for example,
go through all the possible combinations of letters and numbers until the right
password is found.
As a measure of protection against such attacks, the maximum allowed
number of unsuccessful attempts to Login can be set. If this limit is reached,
the access will be barred for a certain length of time.
These parameters apply globally to all configuration options (outband, telnet,
TFTP/ELSA LANconfig and SNMP). If barring is activated on one port all other
ports are automatically barred too.
The following entries are provided in the ELSA LANconfig for configuring
login barring in the 'Management' configuration area on the 'Security' tab or
under
/Setup/Config-module in the menu:
'Lock configuration after' (
Login-errors)
'Lock configuration for' (
Lock-minutes)
4.1.3 Access control via TCP/IP
Access to the internal functions of the devices through TCP/IP can be
restricted using a special filter list. Internal functions in this case means
telnet or TFTP sessions to configure the ELSA LANconfig.
This table is empty by default and so access to the router can therefore be
obtained by TCP/IP using telnet or TFTP from computers with any IP address.
The filter is activated when the first IP address with its associated network
mask is entered and from that point on only those IP addresses contained in
this initial entry will be permitted to use the internal functions. The circle of
authorized users can be expanded by inputting further entries. The filter
entries can describe both individual computers and whole networks.
The access list can be found in the ELSA LANconfig in the 'TCP/IP'
configuration section on the 'General' tab, or in the
/Setup/TCP-IP-
module/Access-list
menu.
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4.2 Security for your LAN
You certainly would not like any outsider to have easy access to or to be able
to modify the data on your computer. The ELSA LANCOM DSL/25 Office
offers you various ways of restricting access from outside:
Access protection using name and password
Data packet filtering
IP masquerading (also known as NAT or PAT)
4.2.1 Security check
The “identifier” to be used for determining the caller can be specified in the
'Communication' configuration section under the 'Call accepting' tab, or
under the
/Setup/WAN-module/Protect menu. You have a choice of
the following:
all calls are accepted from any remote station.
by name: Only calls from those remote stations entered in the name list
are accepted.
by number: Only calls from those remote stations entered in the number
list are accepted.
by name or number: Only calls from those remote stations entered in the
name list or number list are accepted.
It is an obvious requirement for identification that the corresponding
information is also sent by the caller.
Verification of name
The name of the remote station can also be transferred in PPP connections.
The routers' response is obvious: Only those calls with recognized names are
accepted if protection by name is set; all others are rejected.
The name sent by the remote station will be checked for its appearance on
the PPP list of user names if the PPP protocol is being used. If the user name
is not available, the device name is accepted and verified as the name of the
remote station. The PPP list can be found in the ELSA LANconfig in the
'Communication' configuration section on the 'Protocols' tab, or in the
/Setup/WAN-module/PPP-list menu.
No password? The PPP does indeed offer this special option: It is also
possible here to request a form of protection available specifically to this
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protocol based on PAP (Password Authentication Protocol), CHAP (Challenge
Handshake Authentication Protocol) or MS CHAP (a Microsoft variety of
CHAP). This is a form of protection which your device demands from the
remote station.
Obviously you will not need to use the PAP, CHAP or MS CHAP security
procedures if you are using the ELSA LANCOM DSL/25 Office to dial up an
Internet service provider yourself, for example. You will probably not be able
to persuade the ISP to respond to a request for a password...
And where do a caller's name and password come from?
In PPP connections, the name and password is sent to the remote station
during the call establishment, in the Dial-up Networking connection window
for example. The device name, password and user name in the PPP list are
used if the router establishes the connection itself.
4.2.2 Checking the number
Access to your own network is granted if the call number appears in the
number list, or the caller is called back if the callback option is activated. If
the ELSA LANCOM DSL/25 Office is set to provide security using the
telephone number, any calls from remote stations with unknown numbers are
denied access.
Callback
The callback function offers a special form of access privilege: This requires
the 'Callback' option to be activated in the name list for the desired caller and
the call number to be specified, if required.
You can use the settings in the name and number list and the selection of the
protocol to control the callback action of your router:
The router can refuse to call back.
It can call back using a preset call number.
The caller can opt to specify the call number to be used for callback.
And all the while you can use the settings to dictate how the cost of the
connection is to be apportioned. The router accepts all unit charges, except
for the unit required to send the name, if call back 'With name' is set in the
name list. Likewise, a unit is charged to the router, if the caller is not
identified by means of CLI. On the other hand, the caller incurs no costs if
identification of the caller's number is possible and is accepted.
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If the router is requested to call back, the Fast Call Back procedure (patent
pending) can be used with many other parties. This speeds up the callback
procedure considerably.
4.2.3 The hiding place—IP masquerading (NAT, PAT)
One of today's most common tasks for routers is connecting the numerous
workstation computers in a LAN to the network of all networks, the Internet.
Everyone should have the potential to access the WWW from his workstation
and be able to fetch bang up-to-date information for his work.
But this provokes objections from the network manager responsible for the
security of data on the company's network: Every workstation computer on
the WWW? Surely this means that anyone can get in from outside?—Not
true!
IP masquerading provides a hiding place for every computer while connected
with the Internet. Only the router module of the unit and its IP address are
visible on the Internet. The computers in the LAN then use the router as a
gateway so that they themselves cannot be detected. To do this, the router
separates Internet and intranet, as if by a wall. Therefore, IP masquerading
is also called a “firewall function”.
The use of IP masquerading is set individually for each route in the routing
table. The routing table can be found in the ELSA LANconfig in the 'TCP/IP'
configuration section on the 'Router' tab, or in the
/Setup/IP-
router/IP-routing
menu.
For further information, see the 'IP Routing: IP masquerading' section.
4.3 Call charge management
The capability of the router to automatically establish connections to all
required remote sites and close them again when no longer required provides
users with extremely convenient access, e.g. to the Internet. However, quite
substantial costs may be incurred by data transfer over paid lines if the router
is not configured properly (e.g. in the filter configuration) or by excessive use
of the communications opportunities (e.g. extended surfing in the Internet).
To reduce these costs, the software provides various options:
The available online minutes can be restricted to a specific period.
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4.3.1 Limiting the number of online minutes
Depending on the provider, the costs for ATM connection are calculated
based on time.
The telephone charges can be controlled by limiting the maximum connection
time. A time limit within a given period must be set for this purpose. In the
router's default state, for example, ATM connections may only be established
for a maximum of 210 minutes per week.
When the limit of a budget is reached, all open connections will be shut down
automatically. The budgets will not be reset to permit the establishment of
connections until the current period has elapsed. Needless to say, the
administrator can reset the budgets at any time if required!
4.3.2 Settings in the charge module
The interface settings for the ELSA LANconfig can be found in the
'Management' configuration section on the 'Costs' tab, or under
/Setup/Charges-module during telnet or terminal sessions.
In the charge module, the online time and registered charges can be set,
monitored and used to control call establishment.
Day(s)/Period
Duration of the monitoring period in days
Minutes budget
The maximum online minutes in a monitoring period
Spare-units
Available online minutes remaining in the current period
Router-units
Used online minutes by router units over all periods
Router-units
All charges incurred through the unit
Table-budget, time-table
Tables with charges or times for the respective modules
The current charge and connect-time information is retained when rebooting
(e.g. when installing new firmware) is not lost until the unit is switched off.
All of the time values indicated here are in minutes.
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4.4 ATM connections
A ELSA LANCOM DSL/25 Office connects networks via ATM fixed
connections (PVCs) or ATM dial-up connections (SVCs). In order to provide
data transmission via the ATM line, the corresponding parameters must be
entered in the router.
4.4.1 Connection settings
Some of the parameters for data transmission in the ATM network are the
same for all connections and are only configured once for the connection.
In the 'Communication' configuration area on the 'General' register card,
the calling number (or several calling numbers if necessary) is entered, to
which the router should respond. The first calling number entered is used
for outgoing calls. In addition, select whether the custom calling number
should be displayed at the remote station.
The calling numbers in the ATM network are always entered in the complete
international format without the beginning zeros!
Subaddresses can be attached separately to actual calling numbers by a
period.
When configuring via telnet, enter these values in the
/Setup/WAN-
module/Router-interface-list
menu.
In the 'Management' configuration area on the 'Interfaces' register card,
you will find the interface settings. The following values can be
entered for the ATM interface.
Protocol for the signalization channel
A dialing prefix if necessary
The number of the virtual connection path (VPI)
The physical connection speed (Line Cell Rate LCR)
Traffic contract for signalization channel
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When configuring via telnet, enter these values in the /Setup/WAN-
module/Router-interface-list
menu.
The traffic contract established here refers exclusively to the signalization
channel during dial-up connections. This setting does not effect the data
transmission channels! Traffic contracts can be established in the
'Communication' configuration area on the 'General' register card or via
telnet under
/setup/WAN-modul/verkehrskontrakte.
Your provider has provided the values for your ATM connection.
4.4.2 Layer list
With a layer, a collection of protocol settings are defined, which should be
used when connecting to specific remote stations. The list of the
communication layer is found in the 'Communication' configuration area on
the 'General' register card.
In addition to the name which designates the layer, the following values can
be entered:
Encapsulation, either LLC/SNAP or Transparent
Layer 3 protocol, either PPP or Transparent
Layer 2 protocol, either SSCOP or Transparent
Compression of data as an option
Layer 1 protocol is preset securely at value 'AAL-5'.
When configuring via telnet, enter these values in the
/Setup/WAN-
module/Layer-list
menu.
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4.4.3 Traffic contracts
In a traffic contract, the features of an ATM connection are provided on the
'Communication' register card under an available name that can be
dialed.These features are as follows:
Type of traffic contract
variable bit rate
non-set bit rate
constant bit rate
ISDN for remote stations in the ISDN network
The quality of service (0 to 5) is the desired QoS class. The 'Default' entry
corresponds to the type which is normally used for the set type of traffic
contract.
The basic part of the transmitted bandwidth (Sustainable Cell Rate, SCR)
when sending and receiving data must only be entered for VBR traffic
contract types.
The maximum bandwidth transmitted at peak levels (Peak Cell Rate, PCR)
when sending and receiving data must be entered for all traffic contract
types except 'ISDN-HDLC-64 KB/s'.
The length of a SCR transgression in ATM cells (Maximum Burst Size,
MBS) when sending and receiving data must only be entered for VBR
traffic contract types.
If a '0' value is entered in the Rx fields of SCR, PCR or MBS, the corresponding
Tx value is used.
Your provider has provided the values for the traffic contracts.
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When configuring via telnet, enter these values in the /Setup/WAN-
module/Traffic-contracts
menu.
4.4.4 List of fixed connections
With the entry in the list of fixed connections on the 'Remote site' register
card, a connection between a specific remote station and the virtual
transmission channel in the ATM network is established.
All other parameters for fixed connections are included by using the remote
station name from the corresponding tables.
When configuring via telnet, enter these values in the
/Setup/WAN-
module/Fixed-connection
menu.
4.4.5 Name list
With the entry in the name list, a connection between the virtual
transmission channel in the ATM network and the protocol layer and traffic
contract used during this transmission is established. Designate this
assignment which can be indicated in the routing table as a directory for
specific data packets from your local network. The name list is located in the
'Communication' configuration area on the 'Remote site' register card.
The name list contains entries with the following parameters:
Name
Indicate a meaningful name for the connection. This name can then be
selected as 'Router' in the routing table.
Subscriber number
The calling numbers in the ATM network are always entered in the
complete international format without the beginning zeros!
With fixed connections, the calling number does not need to be indicated.
WAN-layer
Select the communication layer which should be used for this connection.
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Traffic contract
Select the traffic contract which should be used for this connection.
Automatic callback
For dial-up connections, you can establish whether and according to
which procedure the calling remote station should be called back.
When configuring via telnet, enter these values in the
/Setup/WAN-
module/Name-list
menu.
4.5 Point-to-point protocol
ELSA routers also support the point-to-point protocol (PPP). PPP is a generic
term for a whole series of WAN protocols which enable the interaction of
routers made by different manufacturers since this protocol is supported by
practically all manufacturers.
Due to the increasing importance of this protocol family and the fact that PPP
is not associated with any specific operating mode of the routers, we will be
introducing the functions of the devices associated with the PPP here in a
separate section.
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4.5.1 The protocol
What is PPP?
The point-to-point protocol was developed specifically for network
connections via serial channels and has asserted itself as the standard for
connections between routers. It implements the following functions:
Password protection according to PAP, CHAP or MS-CHAP
Negotiation of the network protocol to be used over the connection
established (IP or IPX, for example). Included in this are any parameters
necessary for these protocols, for example IP/IPX addresses. This
negotiation runs via the IPCP protocol (IP Control Protocol).
Verification of the connection through the LCP (Link Control Protocol)
PPP is the standard used by router connections for communication between
devices or the WAN connection software of different manufacturers.
Connection parameters are negotiated and a common denominator is agreed
using standardized control protocols (e.g. LCP, IPCP, CCP) which are
contained in PPP, in order to ensure successful data transfer where possible.
What is PPP used for?
It is best to use the point-to-point protocol in the following applications:
for reasons of compatibility when communicating with external routers,
for example
Internet access (when sending addresses)
The phases of PPP negotiation
Establishment of a connection using PPP always begins with a negotiation of
the parameters to be used for the connection. This negotiation is carried out
in four phases which should be understood for the sake of configuration and
troubleshooting.
Establish phase
Once a connection has been made at the data communication level,
negotiation of the connection parameters begins through the LCP.
This ascertains whether the remote site is also ready to use PPP, and the
packet sizes and authentication protocol (PAP, CHAP, MS-CHAP or none)
are determined. The LCP then switches to the opened state.
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Authenticate phase
Passwords will then be exchanged, if necessary. The password will only
be sent once if PAP is being used for the authentication process. An
encrypted password will be sent periodically at adjustable intervals if
CHAP or MS-CHAP is being used.
Network phase
In ELSA LANCOM DSL/25 Office, the protocols IPCP and IPXCP are
implemented.
After the password has been successfully transmitted, the IPCP and/or
IPXCP network layer can be established.
If the negotiation of parameters is successful for at least one of the
network layers, IP and/or IPX packets can and/or IPX-be transmitted on
the opened (logical) line.
Terminate phase
In the final phase the line is cleared, when the logical connections for all
protocols are cleared.
PPP negotiation in the ELSA LANCOM DSL/25 Office
The progress of a PPP negotiation is logged in the devices' PPP statistics and
the protocol packets listed in detail there can be used for checking purposes
in the event of an error.
The PPP trace outputs offer a further method of analysis. You can use the
command
trace + ppp
to begin output of the PPP protocol frames exchanged during a terminal
session. You can perform a detailed analysis once the connection has been
broken if this terminal session has been logged in a log file.
4.5.2 The PPP list
You can specify a custom definition of the PPP negotiation for each of the
remote sites that contact your net. The PPP list can be found in the ELSA
LANconfig in the 'Communication' configuration section on the 'Protocols'
tab, or in the
/Setup/WAN-module/PPP-list menu.
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The PPP list may have up to 64 entries, containing the following values:
In this column of the
PPP list...
...enter the following values:
Remote site Name the remote site uses to identify itself to your router
Username The name with which your router logs onto the remote site. The
device name of your router is used if nothing is specified here.
Authentication Security method used on the PPP connection ('PAP', 'CHAP', 'MS-
CHAP' or 'none'). Your own router demands that the remote site
observes this procedure. Not the other way round.
This means that 'PAP', 'CHAP' or 'MS-CHAP' security is not useful
when connecting to Internet service providers, who may not wish
to provide a password. Select 'none' as the security attribute for
connections such as these.
Key Password transferred by your router to the remote site (if
demanded).
A string of asterisks (*) in the list indicates that an entry is
present.
Time Time between two checks of the connection with LCP. This is
specified in multiple of 10 seconds (i.e. 2 for 20 seconds, for
instance).
Simultaneously the time between two checks of the connection
according to CHAP. This time is entered in minutes.
The time must be set to '0' for remote sites using Windows 95,
Windows 98 or Windows NT.
Retr. Number of retries for the check attempt. You can eliminate the
effect of short-term line interference by selecting multiple retries.
The connection will only be dropped if all attempts are
unsuccessful. The time interval between two retries is 1/10 of the
time interval between two checks.
Simultaneously the number of the “Configure requests” that the
router maximum sends before it assumes a line error and clears
the connection itself.
Conf, Fail, Term These parameters are used to affect the way in which PPP is
implemented. The parameters are defined in RFC 1661 and are not
described in greater detail here. You will find troubleshooting
instructions in this RFC in connection with the router's PPP
statistics if you are unable to establish any PPP connections.
The default settings should generally suffice.
These parameters can only be modified via SNMP or TFTP (using
ELSA LANconfig)!
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4.5.3 Everything OK? Checking the line with LCP
The devices involved in the establishment of a connection through PPP
negotiate a common behavior during data transfer. For example, they first
decide whether a connection can be made at all using the security procedure,
names and passwords specified.
The reliability of the line can be constantly monitored using the LCP once the
connection has been established. This is achieved within the protocol by the
LCP echo request and the associated LCP echo reply. The LCP echo request
is a query in the form of a data packet which is transferred to the remote site
along with the data. The connection is reliable and stable if a valid response
to this request for information is returned (LCP echo reply). This request is
repeated at defined intervals so that the connection can be continually
monitored.
What happens when there is no reply? First a few retries will be initiated to
exclude the possibility of any short-term line interference. The line will be
dropped and an alternative route sought if all the retries remain unanswered.
The LCP request behavior is configured in the PPP list for each individual
connection. The intervals at which LCP requests should be made are set by
the entries in the 'Time' and 'Retr.' fields, along with the number of retries
that should be initiated without a response before the line can be considered
faulty. LCP requests can be switched off entirely by setting the time at '0' and
the retries at '0'.
4.6 IPX routing
The IPX router transmits data from networks which use IPX/SPX as network
protocol (e.g. Novell networks). When it is entered in the IPX routing table, a
remote network for the computers in the local network is made known. Up
to 16 various networks can be entered in the routing table.
4.6.1 IPX addressing
A complete address in an IPX network consists of three parts: a
networknumber, the MAC address of the network card, and the socket
number.
The network number can be dialed without restrictions. However, the
number must be clear beyond all accessible IPX networks in order to
guarantee a correct allocation.
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The MAC address is securely embedded in each network component.
Only in special cases is another address used in the internal network.
In order to not only address a computer, but also a special service on this
computer, an IPX network uses the socket numbers. Therefore, the
various services are clearly identified.
4.6.2 Information on the LAN
If several separated LANs are required at a location, they do not necessarily
need to have their own cabling. Various logical networks can share a cable.
Various formats for the Ethernet packets are used so that the data of various
networks do not interfere with one another, and a network remains hidden
for the others. These formats are determined by the binding which belongs
to a distinct network number on this cable.
The network number and the accompanying binding must be given so that the
router can recognize to which network it belongs. If the network address
remains at the standard setting of '00000000', the router identifies the
address and binding. The router also selects the network on the connected
cable from which it receives the most SAP replies.
4.6.3 IPX-routing-table
In the IPX routing table, determine which remote stations (rather which other
routers or computers) are accessible for the local network, and identify
several parameters for the connection. The table with a maximum of 16
entries has the following structure:
Remote site
The name of the remote station as it is entered in the corresponding
router on the remote site as device name.
Remote site Network Binding Propagated Backoff
BRANCH01 00000245 802.3 Route On
BRANCH02 00000320 SNAP Filt. On
HEAD OFFICE 00000420 802.2 Filt. Off
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Network
Address of the WAN. This is not the address of the target network, but
rather a third address which represents the network between the both
networks to be connected. This applies to:
LAN address 1 ≠ WAN address 1 = WAN address 2 ≠ LAN address 2 ≠
LAN address 1
Binding
Here it is determined which Ethernet binding should be used on the
WAN. This entry is only effective when the layer for this connection
supports Ethernet encapsulation. If the entry is missing, 802.3 is used.
Propagated
Filter for IPX packets of type 20 (NetBIOS propagated frames). The
network basic input/output system was originally developed for IBM and
is also now used by Microsoft in a modified form. This protocol provides
services such as name resolution, data security, and correct packet series
in layer 3 and 4 of the OSI model (secured protocol). NetBIOS packets
contain a special packet type and socket (propagated packets). NetBIOS
is primarily used for data exchange between stations in a local network
(LAN).
These IPX packets can be excluded from data transmission or routed with
the 'Filter' setting. With the 'Route' setting, packets are transmitted
when there is a connection to the corresponding remote station or an
unoccupied channel is still available for the establishment of another
connection. If all lines are busy with other remote stations, the
propagated frames are discarded.
Backoff
The IPX router uses a special algorithm (exponential backoff) in order to
keep connection costs down during faulty configurations.
If a server is not available in the network of the remote station (e.g.
remote access of a workstation), then the backoff function should be
disabled (see 'Exponential backoff').
The default state is 'on'.
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4.6.4 What happens during data transfer in the IPX network?
When a device logs on in an IPX network, it sends a request to the service
advertising protocol (SAP) and then locates the next accessible server (Get
Nearest Server Request) in the network with the number '00000000'. If there
is a router or server in this network, it will respond to this request and
indicate the correct network number.
The servers regularly send information about which services they provide and
which other networks they are able to access. They also use special data
packets according to the service advertising protocol or routing information
protocol (RIP).
When the IPX router is configured and connected, it establishes connection
to all remote stations accessible via the routing tables and exchanges SAP
and RIP information with these networks. The router stores this data in its
internal SAP and RIP tables.
4.6.5 RIP and SAP tables
The RIP and SAP information is sorted alphabetically in the corresponding
tables. RIPs are arranged only according to the network, whereas SAPs are
arranged at first according to service type then according to server name.
RIP and SAP tables are matched with each new RIP or SAP packet. So that
only such services are provided (SAP) which are also accessible (RIP), the
router includes only this SAP information in its table, for which there is also
a corresponding RIP entry. Besides the information on accessible routes and
services, the entries of the tables also indicate, for example, how many
routers must be crossed before reaching the destination (hops) or how much
time a data packet requires in order to reach the destination network (tics =
ca. 1/18 seconds). If, for example, several routes are offered to a destination
network via the RIP information, the router selects the route with the least
tics and the smallest hopcount according to the tables and stores only this
route.
RIP tables can contain 64 entries, SAP tables can contain 128 entries. When
each new packet updates the tables, the older entries will naturally
disappear after some time. In addition, the entries become artificially aged.
For all entries in the RIP/SAP tables which were acquired via local data
exchange, the age is increased every 60 seconds by one. A new RIP or SAP
packet for an entry sets the age back to zero. After an adjustable age from 1
to 60, the route or service is designated as inaccessible (Down). If double this
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amount of time has transpired, the entry is removed. In addition, all RIP and
SAP information concerning this remote station is deleted from the tables
when a connection is established and is replaced with new information.
4.6.6 There are so many routers here...
If connection setup to more remote stations is simultaneously desired in a
network than a router can realize, then it is time for a second (third...) router.
In order for the interaction of the routers to function smoothly and to ensure
that the network always locates a contact partner, the same entries are
carried out in the routing table in all routers. The same routing information
is transmitted to each router with higher tic and hopcount via RIP packets
(
Setup/IPX-module/LAN-config/RIP-SAP-scal. connect).
These routes are thus highlighted as reserves when all channels are occupied
on the device that is addressed.
4.6.7 Redundant routes
If a router receives information with a RIP packet about routes having the
same tic and hopcount as its own routes (redundant routes), these routes
naturally do not have to be disclosed to the sender again. It sends these
routes only to the router which has not propagated the route. This procedure
is called split horizon.
Should it become necessary to disclose redundant routes in the local
network, the function 'loop-propagating' can be used (
SETUP/IPX-
module/LAN-config/LOOP-prop.
). The routes thus acquired are
designated in the RIP table as 'LOOP'. Even though the distribution of
redundant routes is not prohibited according to Novell specifications, it
should not be used if possible and so the default setting is 'OFF'.
4.6.8 Exponential backoff
In order to receive routing information (RIP and SAP information) of the IPX
remote stations that is necessary for the operation, the IPX router of the
device attempts to establish corresponding connections after the device is
turned on. In case this is not possible because of a faulty configuration of the
IPX router, the exponential backoff algorithm prevents connections from
being established thus saving costs.
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If the first connection attempt to a remote station is not successful, the router
attempts to reach the remote station after a continuously increasing waiting
period. The waiting period is determined as follows:
The first dial occurs after 10 + x seconds. x is a digit between 0 and 10.
The second attempt begins approximately 10 + x seconds after the first
unsuccessful attempt. x now stands for a digit between 0 and 20.
The top value for x is doubled with each new attempt. After 16
unsuccessful attempts, the router finally stops dialing. After 16
attempts, a maximum of a day has gone by as the result of the continuous
increase of the waiting period.
If all attempts to dial the remote station continuously fail, the route is
blocked. Further connection attempts can be made only when changing the
entry in the routing table.
The time remaining until the next dial and the number of attempts to
establish connection can be found in the network statistics (
status/IPX-
router-statistics/Networks
.
4.6.9 IPX packet filters
With the entries in the routing table, it can be determined which other
networks are accessible. These networks are also accessible for such data
packets which are not actually required in the network of the remote station.
These packets can result in establishing undesired connections thus entailing
costs.
Therefore, appropriate filters must be used. For example, data packets which
are only used for internal communication of the networks can be excluded
from data transmission via WAN or at least restricted:
Propagated frames
These special data packets use protocols which cannot actually be
routed. In order to become a part of the common routing, this data is
encapsulated in normal IPX packets and transmitted as a broadcast.
Sometimes these packets are not desired when routing. Therefore, you
can explicitly adjust whether this packet type should be routed or filtered.
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Socket filter
Each data packet in an IPX network not only contains target and source
addresses but also target and source sockets. Sockets designate the
processes for which the data in the packet are determined.
For the sockets from local as well as remote networks, there is a
corresponding filter table which contains the filters, with which
individual target sockets or complete socket groups can be excluded from
data transmission. Several sockets, which are known to be frequently
used for undesired connections, are entered by default in the socket filter
table.
RIP and SAP information
Via RIPs, a router informs other routers of all known routes (routes in
other networks) according to the split horizon principle. This includes not
only the entries from its own routing table, but also all routes which the
router acquired from other routers. It acquires routes not only from
routers from local networks, but also from remote networks. The router
enters all available routing information in its internal RIP table.
In SAP information, the servers provide their services. The various
services are represented within the SAP information by numbers. Each
service (e.g. file server or print server) has a distinct number. The router
includes the information on available services in the internal SAP table,
and also enters which service in which network on which MAC address
is available. It also learns whether the service provided is local or in a
remote network, and can thus propagate the service without establishing
a connection.
In the IPX module (
setup/IPX-module/RIP-config or SAP-
config
) of the routers, the RIP and SAP tables are displayed with current
values.
RIP and SAP information is naturally very important for the
communication of devices in a network, therefore there are various
options in adjusting the transmission of these packets.
With a LAN and WAN filter table, the router can be ordered not to
include information on routes to specific networks or specific
available services in the internal RIP or SAP table. Therefore, the
concerned routes are not used and are no longer disclosed. The
services are not provided in their own network.
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RIP and SAP packets are always transmitted without filters.
However, these packets occupy a part of the connection line in all
cases.
The RIP and SAP packets are only sent when there are changes in the
information.
RIPs and SAPs can be transmitted in regular, adjustable time periods.
Normally, the information is sent in one-minute intervals. With the
time setting, intervals can be extended up to 60 minutes.
The most economical handling of RIP and SAP packets transmits
information only when a connection is established.
IPX and SPX watchdogs:
With these data packets, the servers are informed e.g. at workstations
whether they are still active or whether they can be shut down, if
necessary. So that this “Hello, are you still awake?” packet for
computers in a remote network does not continuously establish a
connection, the reply for these requests can be adjusted as follows:
IPX watchdogs remain completely unanswered. After the time has
been set on the server, the computers are shut down.
IPX and SPX watchdogs can be answered locally. This procedure is
called spoofing. The router then answers instead of the computers
being addressed, which are naturally never shut down. Setting a
time on the server, according to which the corresponding devices are
shut down in all cases, is also sensible.
IPX and SPX watchdogs can naturally be routed, thus frequently
establishing connection.
Additional information on IPX, IPX router, and accompanying parameters is
found in the chapter 'Setup/IPX module' in the reference manual.
4.7 IP routing
An IP router works between networks which use TCP/IP as the network
protocol. This only allows data transmissions to destination addresses
entered in the routing table. This chapter explains the structure of the IP
routing table of an ELSA router, as well as the additional functions available
to support IP routing.
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4.7.1 The IP routing table
Use the IP routing table to tell the router which remote station (which other
router or computer) it should send the data for particular IP addresses or IP
address ranges to. This type of entry is also known as a “route” since it is
used to describe the path of the data packet. This procedure is also called
“static routing” since you make these entries yourself and they remain
unchanged until you either change or delete them yourself. Naturally, there
is also “dynamic routing” too. The routers use the routes in this way to
exchange data between themselves and continually update it automatically.
The static routing table can hold up to 64 entries, the dynamic table can hold
128. The IP router looks at both tables when the IP RIP is activated.
You also use the IP routing table to tell the router the length of this route's
path so that it can select the most suitable route in conjunction with IP RIP
where there are several routes to the same destination. The default setting
for the distance to another router is 2, i.e. the router can be reached directly.
All devices which can be reached locally, such as other routers in the same
LAN or workstation computers connected via Proxy ARP are entered with the
distance 0. The “quality level” of this route will be reduced if the entry
addressed has a higher distance (up to 14). “Unfavorable” routes like this will
only be used if no other route to the remote station in question can be found.
The routing table can be found in the ELSA LANconfig in the 'IP router' on the
'Routing' tab, or in the
/Setup/IP-router/IP-routing-table.
This, then, is how an IP routing table might look:
What do the various entries on the list mean?
IP address and Netmask
This is the address of the destination network to which data packets may
be sent and its associated network mask. The router uses the network
IP address IP netmask Router name Distance Masquerade
192.168.120.0 255.255.255.0 AACHEN 2 On
192.168.125.0 255.255.255.0 BERLIN 3 Off
192.168.130.0 255.255.255.0 191.168.140.123 0 Static
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mask and the destination IP address of the incoming data packets to
check whether the packet belongs to the destination network in question.
The route with the IP address “255.255.255.255” with network mask
“0.0.0.0” is the default route. All data packets that cannot be routed by
other routing entries are sent over this route.
Router
The router transmits the appropriate data packets to the IP address and
network mask to this remote station. A name is entered at this point if
the remote station is a router in another network or an individual
workstation computer. This is where the IP address of another router
which knows the path to the destination network is entered if the router
on the network cannot address the remote station itself.
The router name indicates what should happen with the data packets
that match the IP address and network mask.
Routes with the router name “0.0.0.0” identify exclusion routes. Data
packets for this “zero route” are rejected and are not routed any further.
This is how routes which are forbidden on the Internet (private address
spaces, e.g. 10.0.0.0), for example, are excluded from transmission.
If an IP address is input as router name, this is a locally available router,
which is responsible for transfer of the relevant data packets.
Distance
Number of routers between your own and the destination router. This
value is often equated with the cost of the transmission and used to
distinguish between inexpensive and expensive call paths for wide-area
connections. The distance values entered are propagated as follows:
All networks which can be reached while a connection exists to a
destination network are propagated with a distance of 1.
All non-connected networks are propagated with the distance
entered in the routing table (but with a minimum distance of 2) as
long as a free transmitting channel is still available.
The remaining networks are propagated with a distance of 16 (=
unreachable) if there are no longer any channels available.
Remote stations connected using Proxy ARP are an exception to this.
These “Proxy hosts” are not propagated at all.
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Masquerade
Use the 'Masquerade' option in the routing table to inform the router
which IP addresses to use when transferring the packets.
'Off': No masquerading.
'On': This entry requests a random IP address valid in the Internet
from your provider which is then used for the connection and
masquerading.
'Stat.': Use this entry to request the assignment of a specific IP
address from your provider as entered in the 'TCP/IP' configuration
section on the 'General' tab or in the
/Setup/TCP-IP-module
menu. This address will be used for the connection and
masquerading.
For further information see the 'IP masquerading' section.
Examples with explanatory notes:
IP address Netmask Router Distance This is what happens:
192.168.1.9 255.255.255.255 FIELD SERVICE 2 The FIELD SERVICE remote station can be
reached at IP address 192.168.1.9.
192.168.120.0 255.255.255.0 ROUTER01 2 All data packets with destination IP
addresses 192.168.120.x are transmitted
to ROUTER01.
192.168.125.0 255.255.255.0 ROUTER02 3 All data packets with destination IP
addresses 192.168.125.x are transmitted
to ROUTER02.
192.168.130.0 255.255.255.0 192.168.140.123 0 All data packets with the destination IP
addresses 192.168.130.x are sent to the
locally available router with the IP address
192.168.140.123.
192.168.0.0 255.255.0.0 0.0.0.0 0 Excludes transmission of all data packets
to networks using private address spaces.
172.16.0.0 255.255.0.0 0.0.0.0 0
10.0.0.0 255.0.0.0 0.0.0.0 0
224.0.0.0 224.0.0.0 0.0.0.0 0
255.255.255.255 0.0.0.0 HEAD OFFICE 2 All data packets which cannot be allo-
cated to the entries listed above are trans-
mitted to the HEAD OFFICE remote station.
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The sequence of the entries is important here: They are processed from top
to bottom. The router sorts entries automatically: Firstly by network masks,
in descending order. Then by the IP addresses, in ascending order. This
places the 'HEAD OFFICE' entry at the very end of the list. If this entry were
at the top of the list, the router would send all (!) data packets not belonging
to the local network to the network of the head office.
4.7.2 TCP/IP packet filters
You can use your entries in the routing table to determine quite precisely
which data should be transferred. Additionally, you can use the '0.0.0.0' entry
in the 'Router' field to reject whole groups of IP addresses.
Occasionally, you may wish to restrict a transmission even further. You can
do this using a characteristic of TCP/IP, which is to send port numbers for
destination and source as well as the source and destination IP addresses
with a data packet. The destination port in a data packet stands for the
service to be addressed in the TCP/IP network. The destination ports are
fixed for the various services on the TCP/IP network (see also 'TCP/IP-ports'
in the reference section). The source ports, on the other hand, may be
selected freely within certain ranges.
The router can check the source and destination ports of data packets using
the TCP or UDP protocols. It can then deduce the purpose of the data from
these ports. For example, FTP accesses or telnet sessions can be identified.
The appropriate filter table can be used to determine that certain data is not
to be transferred from the LAN to the WAN. Data for particular ports can also
be blocked from entering the LAN from the WAN in the same way.
The filter tables can use the filter type along with the definition of the port
ranges and associated protocols to determine whether the data in question
should never be transmitted or whether it should simply not lead to a call
being established (i.e. only be transmitted if a connection already exists).
These filter tables can be found in the ELSA LANconfig in the 'TCP/IP'
configuration section on the 'Filter' tab, or in the
/Setup/IP-router
menu.
4.7.3 Proxy ARP
The proxy ARP is a special feature of the IP router. This proxy is used if the
transmission of data to IP addresses takes place in the same logical network
as the sender, but the destination address is still reached via a router. This
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is the case when individual workstation computers (teleworkers) are
networked via TCP/IP to the company network. The teleworker then has an
IP address which is located in the same local network as all the other
computers in the LAN. A data packet from LAN to the teleworker would
usually only search for a receiver locally, but would not be able to find one.
To take advantage of this function, enable the 'Proxy ARP active' option (in
LANconfig in the 'IP router' configuration section on the 'General' tab or in the
/Setup/IP-router-module menu for other configuration modes).
The router becomes a proxy for the teleworker with the following entry in the
routing table:
Proxy hosts are not propagated in an RIP packet because the router responds
to an ARP request for the proxy computer with its own MAC address. The
distance is set to '0' on the routing table to indicate this clearly.
The router now responds to the request for the MAC address to the IP address
192.168.110.123 with its own MAC address. This ensures that all packets in
the LAN for the teleworker are now automatically sent to the router, and that
data is sent on to the computer at the other end of the ISDN connection.
4.7.4 Local routing
You know the following behavior of a workstation within a local network.
The computer searches for a router to assist with transmitting a data packet
to an IP address which is not on its own LAN. This router is usually notified
to the operating system by its property of being the default router or gateway.
It is often only possible to enter one default router which is supposed to be
able to reach all the IP addresses which are unknown to the workstation
computer if there are several routers in a network. Occasionally, however,
this default router cannot reach the destination network itself but does know
another router which can find this destination.
How can you assist the workstation computer now?
By default, the router sends the computer a response with the address of the
router which knows the route to the destination network (this response is
IP address Netmask Router Distance Masquerade
192.168.110.123 255.255.255.255 Teleworker01 0 off
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known as an ICMP redirect). The workstation computer then accepts this
address and sends the data packet straight to the other router.
Certain computers, however, do not know how to handle ICMP redirects. To
ensure that the data packets reach their destination anyway, use local
routing (in ELSA LANconfig in the 'IP router' configuration section on the
'Routing' tab or in the
/Setup/IP-router-module/Loc.-
routing On
menu). In this way you instruct the router itself in your device
to send the data packet to other routers. In addition, in this case no more
ICMP redirects will be sent.
This may seem to be a good idea in principle, but local routing should still only
be used as a last resort, since this function leads to doubling of the number
of data packets being sent to the destination network required. The data is
first sent to the default router and is then sent on from here to the router
which is actually responsible in the local network.
4.7.5 Dynamic routing with IP RIP
In addition to the static routing table ELSA routers also have a dynamic
routing table containing up to 128 entries. Unlike the static table, you do not
fill this out yourself, but leave it to be dealt with by the router itself. It uses
the Routing Information Protocol (RIP) for this purpose. All devices that
support RIP use this protocol to exchange information on the available routes.
What information is propagated by IP RIP?
A router uses the IP RIP information to inform the other routers in the network
of the routes it finds in its own static table. The following entries are ignored
in this process:
Rejected routes with the '0.0.0.0' router setting.
Routes referring to on other routers in the local network.
Routes linking individual computers to the LAN by proxy ARP.
Although the entries in the static routing table are set manually, this
information changes according to the connection status of the router and so
do the RIP packets transmitted.
If the router has established a connection to a remote station, it
propagates all the networks which can be reached via this route in the
RIPs with the distance '1'. Other routers in the LAN are thus informed by
these means that a connection to the remote station has been
established on this router which they can use. The establishment of
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additional connections by routers with dial-up connections can be
prevented, thus reducing connection costs.
If this router cannot establish a further connection to another remote
station, all other routes are propagated with the distance '16' in the RIPs.
The number '16' stands for “This route is not reachable at the moment.”
A router may be prevented from establishing a connection in addition to
the present one may be due to one of the following causes:
To take advantage of this function, enable the 'IP RIP' option (in the ELSA
LANconfig in the 'TCP/IP' configuration section on the 'Router' tab or in the
Setup/IP-router-module menu for other configuration modes).
Routers with RIP capabilities dispatch the RIP packets approximately every 30
seconds. The router is only set up to send and receive RIPs if it has a unique
IP address. The IP RIP module is deselected in the default setting using the
IP address XXX.XXX.XXX.254.
Which information does the router take from received IP RIP
packets?
When the router receives such IP RIP packets, it incorporates them in its
dynamic routing table, which looks something like this:
What do the entries mean?
IP address and network mask identify the destination network, the distance
shows the number of routers between the transmitter and receiver, the last
column shows which router has revealed this route. This leaves the 'Time'.
The dynamic table thus shows how old the relevant route is. The value in this
column acts as a multiplier for the intervals at which the RIP packets arrive.
A '1', therefore, stands for 30 seconds, a '5' for about 2.5 minutes and so on.
New information arriving about a route is, of course, designated as directly
reachable and is given the time setting '1'. The value in this column is
automatically incremented when the corresponding amount of time has
IP address Netmask Time Distance Router
192.168.120.0 255.255.255.0 1 2 192.168.110.1
192.168.130.0 255.255.255.0 5 3 192.168.110.2
192.168.140.0 255.255.255.0 1 5 192.168.110.3
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elapsed. The distance is set to '16' after 3.5 minutes (route not reachable)
and the route is deleted after 5.5 minutes.
Now if the router receives an IP RIP packet, it must decide whether or not to
incorporate the route contained into its dynamic table. This is done as
follows:
The route is incorporated if it is not yet listed in the table (as long as there
is enough space in the table).
The route exists in the table with a time of '5' or '6'. The new route is then
used if it indicates the same or a better distance.
The route exists in the table with a time of '7' to '10' and thus has the
distance '16'. The new route will always be used.
The route exists in the table. The new route comes from the same router
which notified this route, but has a worse distance than the previous
entry.
RIP packets from the WAN will be ignored and will be rejected immediately.
RIP packets from the LAN will be evaluated and will not be propagated in the
LAN.
Interaction: static and dynamic tables
The router uses the static and dynamic tables to calculate the actual IP
routing table it uses to determine the path for data packets. In doing so, it
includes the routes from the dynamic table which it does not know itself or
which indicate a shorter distance than its own (static) route with the routes
from its own static table.
Routers without IP RIP support
Routers which do not support the Routing Information Protocol are also
occasionally present on the local network. These routers cannot recognize
the RIP packets and look on them as normal broadcast or multicast packets.
Connections are continually established by the RIPs if this router holds the
default route to a remote router. This can be prevented by entering the RIP
port in the filter tables.
Scaling with IP RIP
If you use several routers in a local network with IP RIP, you can represent the
routers outwardly as one large router. This procedure is known as “scaling”.
A router like this, with its supposedly inexhaustible supply of routes is
created by the continual exchange of information between the routers.
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4.7.6 IP masquerading (NAT, PAT)
One continually growing problem for the Internet is the limited number of
generally valid IP addresses available. In addition to this, the allocation of
fixed IP addresses for the Internet by the Network Information Center (NIC) is
an expensive process. What is more obvious than having several computers
share one IP address?
This particular solution is called IP masquerading. This is a procedure
whereby only one LAN router appears on the Internet with an IP address. This
IP address is allocated to the router either permanently by the NIC or
temporarily by an Internet provider. All the other computers on the network
then “conceal” themselves behind this one IP address. Aside from the
welcome savings, IP masquerading has the added benefit of guarding very
effectively against attacks on the local network from the Internet.
Two addresses for the router
Masquerading pits two opposing requirements of the router against one
another: While it must have an IP address which is valid on the local network,
it must also have an address valid on the Internet. Since these two addresses
may not in principle be located on the same logical network, there is only one
solution: two IP addresses are required.
The router is therefore assigned an Internet address and an Intranet
address, each with its own fitting network mask. Use the 'Masquerade'
option in the routing table to inform the router which of the two addresses to
use when transferring the packets.
'Off': No masquerading.
'Dynamic': This entry requests a random IP address valid in the Internet
from your provider which is then used for the connection and
masquerading.
'Static': This entry requests a specific IP address entered under
/setup/TCP from your provider which is then used for the connection and
masquerading.
If a specific address is requested from the provider, two options are available
for the actual address assignment:
The provider assigns the desired address to the router. The network
mask now decides how many computers are masked behind the router.
IP address with full '255.255.255.255' network mask: This is your
own unique IP address, registered by the NIC. None of the other
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computers on the network have valid Internet addresses and are
masked behind the router's fixed address.
IP address with an incomplete network mask, e.g. '255.255.255.248':
You have several registered IP addresses, one of which you assign to
the router. The remaining IP addresses are assigned permanently to
devices on the Intranet, which can then use unmasked connections to
access the Internet. The other devices can still access the Internet
using masked connections.
The provider assigns another address to the router. Then all computers
in the local network are masked behind the assigned address.
How does IP masquerading work?
Masquerading makes use of a characteristic of TCP/IP data transmission,
which is to use port numbers for destination and source as well as the source
and destination addresses. When the router receives a data packet for
transfer it now notes the IP address and the sender's port in an internal table.
It then gives the packet its unique IP address and a new port number, which
could be any number. It also enters this new port on the table and forwards
the packet with the new information.
The response to this new packet is now sent to the IP address of the router
with the new sender port number. The entry in the internal table allows the
router to assign this response to the original sender again.
You can view these tables in detail in the router statistics (see also 'Status'
in the reference manual).
Simple and inverse masquerading
This masking operates in both directions: The local network behind the IP
address of the router is masked if a computer from the LAN sends a packet
to the Internet (simple masquerading).
If, on the other hand, a computer sends a packet from the Internet to, for
example, an FTP server on the LAN, from the point of view of this computer
the router appears to be the FTP server. The router reads the IP address of
the FTP server in the LAN from the entry in the service table (in the ELSA
LANconfig in the 'IP router' configuration area on the 'Masq.' tab or in the
menu
Setup/IP-router-module/Masquerading/Service-
table
). The packet is forwarded to this computer. All packets that come
from the FTP server in the LAN (answers from the server) are hidden behind
the IP address of the router.
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The only small difference is that:
Access to a service (port) in the Intranet from outside must be defined in
advance by specifying a port number. The destination port is specified
with the Intranet address of, for example, the FTP server, on a service
table to achieve this.
When accessing the Internet from the LAN, on the other hand, the router
itself makes the entry in the port and IP address information table.
The table concerned can hold up to 2048 entries, that is it allows 2048
simultaneous transmissions between the masked and the unmasked
network.
After a specified period of time, the router, however, assumes that the
entry is no longer required and deletes it automatically from the table.
Which protocols can be transmitted using IP masquerading?
Naturally, only those which also communicate using ports. Protocols working
without port numbers or using ports above IP in the OSI model cannot be
masked without special treatment.
The current version of router implements masquerading for the following
protocols:
TCP (and all protocols based on it such as FTP, HTTP etc.)
UDP
ICMP
4.7.7 DNS forwarding
Names rather than IP addresses are generally used to access a server over
the Internet. Who knows which address is behind 'www.domain.com'? The
DNS server, of course.
DNS stands for Domain Name Service and refers to the assignment of
domain names (such as domain.com) to the corresponding IP addresses. This
information must be constantly updated and be accessible all over the world
at any time. DNS servers holding long tables containing IP addresses and
domain names exist for this purpose.
If a computer calls up a home page from the intranet, it first sends out a DNS
request: “Which IP address belongs to www.domain.com?”
This request is dealt with as follows if the router is registered as the DNS
server for the workstation computers:
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Initially the router checks whether a DNS server has been entered in its
own settings (in ELSA LANconfig in the 'TCP/IP' configuration section on
the 'Addresses' tab or in the
/Setup/TCP-IP-module menu). If it is
successful there, it obtains the desired information from this server.
If no DNS server is entered in the router, it will attempt to reach a DNS
server over a PPP connection (e.g. from the Internet provider) to get the IP
address assigned to the name from there. This can only succeed if the
address of a DNS server is sent to the router during PPP negotiation.
The default route is established and the DNS server searched for there if
no connection exists.
This procedure does not require you to have any knowledge of the DNS server
address. Entering the Intranet address of your router as the DNS server for
the workstation computers is sufficient to enable you obtain the name
assignment. This procedure also automatically updates the address of the
DNS server. Your local network always receives the most current information
even if, for example, the provider sending the address changes the name of
his DNS server or you change to another provider.
4.7.8 Policy-based routing
Policy-based routing describes a process in which particular data packets are
given preferential treatment. This requires evaluation of a special field
within the IP data packet, known as the Type of Service (TOS) field. This
preferential treatment of a number of data packets can, for example, simplify
the configuration of the router via the WAN when large data volumes are to
be transferred simultaneously.
You can find more information on policy based circuit routing in the
'Description of the menu options'.
4.8 Automatic address administration with DHCP
In order to operate smoothly in a TCP/IP network, all the devices in a local
network must have unique IP addresses.
They also need the addresses of DNS server and NBNS server as well as that
of a default gateway through which the data packets are to be routed from
addresses that are not available locally.
In a smaller network, it is still conceivable that these addresses could be
entered manually in all the computers in the network. In a larger network
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with many workstation computers, however, this would simply be too
enormous of a task.
In such situations, the DHCP (Dynamic Host Configuration Protocol) is the
ideal solution. Using this protocol, a DHCP server in a TCP/IP-based LAN can
dynamically assign the necessary addresses to the individual stations.
4.8.1 The DHCP server
As a DHCP server, the ELSA LANCOM DSL/25 Office can administer the IP
addresses in its TCP/IP network. In doing so, it passes the following
parameters to the workstation computers:
IP address
Netmask
Broadcast
DNS server
NBNS
Default gateway
Period of validity for the parameters assigned
The DHCP server takes the IP addresses either from a freely defined address
pool or determines the addresses automatically from its own IP address (or
intranet address).
In DHCP mode, a completely unconfigured device can even automatically
assign IP addresses to itself and the computers in the network.
In the simplest case, all that is required is to connect the new device to a
network without other DHCP servers and switch it on. The DHCP server then
interacts with ELSA LANconfig using a wizard and handles all of the address
assignments in the local network itself.
4.8.2 DHCP—'on', 'off' or 'auto'?
The DHCP server can be set to three different states:
'on': The DHCP server is permanently active. The configuration of the
server (validity of the address pool) is checked when this value is entered.
When correctly configured, the device will be available to the
network as a DHCP server.
In the event of an incorrect configuration (e.g. invalid pool limits), the
DHCP server is disabled and switches to the 'off' state.
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'off': The DHCP server is permanently disabled.
'auto': The server is in automode. In this mode, after switching it on, the
device looks for other DHCP server within the local network. This search
can be recognized by the Tx LED flashing momentarily after activation.
The device then disables its own DHCP server if any other DHCP
servers are found. This prevents the unconfigured device from
assigning addresses not in the local network when switched on.
The device then enables its own DHCP server if no other DHCP
servers are found.
Whether the DHCP server is active or not can be seen in the DHCP
statistics.
The default state is 'auto'.
4.8.3 How are the addresses assigned?
IP address assignment
Before the DHCP server can assign IP addresses to the computers in the
network, it first needs to know which addresses are available for assignment.
Three options exist for determining the available selection of addresses:
The IP address can be taken from the address pool selected (start address
pool to end address pool). Any valid addresses in the local network can
be entered here.
If '0.0.0.0' is entered instead, the DHCP server automatically determines
the particular addresses (start or end) from the IP or Intranet address
settings in the 'TCP-IP-module' using the following procedure:
If only the IP address or only the Intranet address is entered, the start
or end of the pool is determined by means of the associated network
mask.
If both addresses have been specified, the Intranet address has
priority for determining the pool.
From the address used (IP or Intranet address) and the associated
network mask, the DHCP server determines the first and last possible IP
address in the local network as a start or end address for the address
pool.
If the router has neither an IP address of its own nor an Intranet address,
the device has gone into a special operating mode. It then uses the IP
address '10.0.0.254' for itself and the address pool '10.x.x.x' for the
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assignment of IP addresses in the network. In this state, the DHCP server
only assigns IP addresses and their validity to the computers in the
network, but not the other information.
If only one computer in the network is booted and requests an IP address via
DHCP with its network settings, a device with an activated DHCP module will
assign this computer an address. A valid address is taken from the pool as
an IP address. If the computer was already assigned an IP address at some
point in the past, it requests this same address and the DHCP server attempts
to reassign it this address if it has not already been assigned to another
computer.
The DHCP server also checks whether the address selected is still available
in the local network. As soon as the uniqueness of an address has been
established, the requesting computer is assigned the address found.
Netmask assignment
The network mask is assigned in the same way as the address. If a network
mask is entered in the DHCP module, this mask is used for the assignment.
Otherwise, the network mask from the TCP/IP module is used. The order is
the same as during the assignment of the addresses.
Broadcast assignment
Normally, an address yielded from the valid IP addresses and the network
mask is used for broadcast packets in the local network. In special cases,
however (e.g. when using subnetworks for some of the workstation
computers), it may be necessary to use a different broadcast address. In this
case, the broadcast address to be used is entered in the DHCP module.
The default setting for the broadcast address should be changed by
experienced network specialists only. Incorrect configuration of this section
can result in the undesired establishment of connections subject to connect
charges!
DNS and NBNS assignment
This assignment is based on the associated entries in the 'TCP-IP module'.
If no server is specified in the relevant fields, the router passes its own IP
address as a DNS address. This address is determined as described under 'IP
address assignment'. The router then uses DNS forwarding (also see 'DNS
forwarding'), to resolve DNS or NBNS requests from the host.
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Default gateway assignment
The device always assigns the requesting computer its own IP address as a
gateway address.
If necessary, this assignment can be overwritten with the settings on the
workstation computer.
Period of validity for an assignment
The addresses assigned to the computer are valid only for a limited period of
time. Once this period of validity has expired, the computer can no longer use
these addresses. In order for the computer to keep from constantly losing its
addresses (above all its IP address), it applies for an extension ahead of time
that it is generally sure to be granted. The computer loses its address only if
it is switched off when the period of validity expires.
For each request, a host can ask for a specific period of validity. However, a
DHCP server can also assign the host a period of validity that differs from
what it requested. The DHCP module provides two settings for influencing
the period of validity:
Maximum lease time in minutes
Here you can enter the maximum period of validity that the DHCP server
assigns a host.
If a host requests a validity that exceeds the maximum length, this will
nevertheless be the maximum available validity!
The default setting is 6000 minutes (approx. 4 days).
Default lease time in minutes
Here you can enter the period of validity that is assigned if the host
makes no request. The default setting is 500 minutes (approx. 8 hours).
Priority for the DHCP server—request assignment
In the default configuration, almost all the settings in the Windows network
environment are selected in such a way that the necessary parameters are
requested via DHCP. Check the settings by clicking Start Settings
Control Panel Network. Select the 'TCP/IP Protocol' entry for your
network adapter and open Properties.
Check the various tabs for special entries, such as for the IP address or the
standard gateway. If you would like all of the values to be assigned by the
DHCP server, simply delete the corresponding entries.
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Under the 'WINS Address' tab, the 'Use DHCP for WINS Resolution' option
must also be activated if you wish to use Windows networks via IP with name
resolution via NBNS. In this case, the DHCP server must also have an NBNS
entry.
Priority for computer—overwriting an assignment
If a computer uses parameters other than those assigned to it (e.g. a different
default gateway), these parameters must be set directly on the workstation
computer. The computer then ignores the corresponding parameters
assigned to it by the DHCP server.
Under Windows, this can, for example, be performed via the properties of the
network environment.
Click Start Settings Control Panel Network. Select the 'TCP/IP
Protocol' entry for your network adapter and open Properties.
You can now enter the desired values by selecting the various tabs.
The assignment of IP addresses to the various computers can be checked
using the 'Setup/DHCP/Table-DHCP' item in the DHCP module. This table
contains the assigned IP address, the MAC address, the validity, the name of
the computer (if available) and the type of address assignment.
The 'Type' field specifies how the address was assigned. This field can
assume the following values:
new
The computer has made its initial request. The DHCP server verifies the
uniqueness of the address that is to be assigned to the computer.
unknown
While verifying uniqueness, it was determined that the address has
already been assigned to another computer. Unfortunately, the DHCP
server has no means of obtaining additional information on this
computer.
status
A computer has informed the DHCP server that it has a fixed IP address.
This address can no longer be used.
dynamic
The DHCP server assigned an address to the computer.
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4.8.4 Configuring the DHCP server
Basically, two starting points are possible when the devices are configured
as a DHCP server:
You have not yet configured a network or your existing local network
does not use TCP/IP. The DHCP server in your new ELSA lets you assign
IP addresses to all of the computers in the network and to the router in a
single operation.
You are already using TCP/IP but without a DHCP server, and you would
now like to convert to DHCP operation.
Configuration using ELSA LANconfig and the wizards
The ELSA LANconfig includes a wizard to help you with the required settings:
Connect the unconfigured device to your local network using a network
cable. If you are connecting the device to a hub, the node/hub switch
must be set to 'Node'. If you are connecting the router directly to the
network adapter of a computer in your network, set the switch to the
'Hub' position.
Switch the device on. It will not find any other DHCP servers in the
network and will thus enable its own DHCP functions.
If you have not done so already, install the TCP/IP protocol on all
computers in the LAN.
Usually when the protocol is installed, the default configuration is
such that the computers are automatically ready to obtain the IP
address from a DHCP server. After rebooting at the end of the
protocol installation, the computers automatically request an IP
address from the DHCP server.
If the protocol is already installed, enable the DHCP function on all of
the computers in the local network. Under Windows 95, for example,
this is done by selecting Start Settings Control Panel
Network to open the window for configuring network properties.
Double-click the entry for the 'TCP/IP Protocol'.
Enable the 'Obtain an IP address automatically' option. Switch over
to the 'DNS Configuration' tab and delete all of the existing DNS
addresses. Next, delete any entries under the 'Gateway' tab and click
OK to close all the windows. This change will require a reboot, after
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which the computer will automatically request an IP address from the
DHCP server's address pool.
Install the ELSA LANconfig on a computer in the network.
Start the program from the 'ELSAlan' program group. When loading, the
ELSA LANconfig, will detect an unconfigured router in the network and
will launch the wizard for the basic settings.
If you have not previously used any IP addresses in your network,
select the option 'Make all settings automatically' in this wizard and
confirm your selection with Finish in the next window.
The wizard assigns the IP address '10.0.0.1' with the netmask
'255.255.255.0' to the router and enables the DHCP server. On the
basis of this IP address, the device then determines the valid address
pool for the DHCP assignment.
In the event that IP addresses were already in use in your network
before converting to DHCP operation, select the option 'I would like
to adjust the settings manually' in the wizard. In the next window,
enter an unused IP address from the previously-used address range
and activate the DHCP server.
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The wizard now assigns the selected IP address and associated
netmask to the device. On the basis of this IP address, the device
then determines the valid address pool for the DHCP assignment.
After a few seconds, all of the computers in the network will be
checked and are assigned a new IP address by the DHCP server as
required. The computers also receive additional parameters such as
the broadcast address, DNS server, default gateway, etc.
Manual configuration
If configuration using the ELSA LANconfig wizard is not for you, set the
parameters for the DHCP server manually: in ELSA LANconfig in the 'TCP/IP'
configuration section on the 'DHCP' tab or in the /Setup/DHCP
Module menu).
4.9 DNS
The domain name service (DNS) in TCP/IP networks provides the association
between computer names or network names (domains) and IP addresses.
This service is required for Internet communications, to return the correct IP
address for a request such as 'www.elsa.de' for example. However, it's also
useful to be able to clearly associate IP addresses to computer names within
a local network or in a LAN interconnection.
4.9.1 What does a DNS server do?
The names used in DNS server requests are made up of several parts: one
part consisting of the actual name of the host or service to be addressed;
another section specifies the domain. Specifying the domain is optional
within a local network. These names could thus be 'www.domain.com' or
'ftp.domain.com', for example.
If there is no DNS server in the local network, all locally unknown names will
be searched for using the DEFAULT route. By using a DNS server, it's
possible to immediately go to the correct remote station for all of the names
with known IP addresses. In principle, the DNS server can be a separate
computer in the network. However, the following reasons speak for locating
the DNS server directly in the ELSA LANCOM DSL/25 Office:
a ELSA LANCOM DSL/25 Office can automatically distribute IP addresses
for the computers in the local network when in DHCP server mode. In
other words, the DHCP server already knows the names and IP addresses
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of all of the computers in its own network that were assigned IP
addresses via DHCP. With the dynamic address assignments of a DHCP
server, an external DNS server might have difficulties in keeping the
associations between the names and IP addresses current.
When routing Microsoft Networks via NetBIOS, the ELSA LANCOM
DSL/25 Office also knows the computer names and IP addresses in the
other connected NetBIOS networks. In addition, computers with fixed IP
addresses can also enter themselves in the NetBIOS table and thus be
known by their names and addresses.
The DNS server in the ELSA LANCOM DSL/25 Office can also be used as
an extremely convenient filter mechanism. Requests for domains can be
prohibited throughout the LAN, for subnetworks, or even for individual
computers—simply by specifying the domain name.
When processing requests for specific names, the DNS server takes
advantage of all of the information available to it:
First, the DNS server checks whether access to the name is not prohibited
by the filter list. If that is the case, an error message is returned to the
requesting computer stating that access to the address has been denied.
Next, it searches in its own static DNS table for suitable entries.
If the address cannot be found in the DNS table, it searches the dynamic
DHCP table. The use of DHCP information can be disabled if required.
If no information on the name can be located in the previous tables, the
DNS server then searches the lists of the NetBIOS module. The use of
the NetBIOS information can also be disabled if necessary.
If the requested name cannot be found in any of the information sources
available to it, the DNS server sends the request to another server—that of
the Internet provider, for example—using the normal DNS forwarding
mechanism, or returns an error message to the requesting computer.
4.9.2 Setting up the DNS server
The settings for the DNS server can be found in ELSA LANconfig in the
'TCP/IP' configuration section on the 'DNS' tab. To set up the DNS server,
proceed as follows:
Switch the DNS server on.
set setup/DNS-module/operating on
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Enter the domain in which the DNS server is located. The DNS server
uses this domain to determine whether the requested name is located in
the LAN. Entering the domain is optional.
set setup/DNS-module/domain yourdomain.com
Specify whether information from the DHCP server and the NetBIOS
module should be used.
set setup/DNS-module/DHCP-usage yes
set setup/DNS-module/NetBIOS-usage yes
The main task of the DNS server is to distinguish requests for names in
the Internet from those for other remote stations. Therefore, enter all
computers into the DNS table
for which you know the name and IP address,
that are not located in your own LAN,
that are not on the Internet and
that are accessible via the router.
For example, if would like to access the mail server at your headquarters
(name: mail.yourdomain.com, IP: 10.0.0.99) via the router from a branch
office, enter:
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cd setup/DNS-module/DNS-table
set mail.yourdomain.com 10.0.0.99
Stating the domain is optional but recommended.
When you now start your mail program, it will probably automatically
look for the server 'mail.yourdomain.com'. The DNS server thereupon
returns the IP address '10.0.0.99'. The mail program will then look for
that IP address. With the proper entries in the IP routing table and name
list, a connection is automatically established to the network in the
headquarters, and finally to the mail server.
Finally, use the filter list to specify the users that cannot access certain
names or domains.
cd setup/DNS-module/filter-list
set 001 www.offlimits-domain.com 0.0.0.0 0.0.0.0
This entry (with the index '001') prohibits this domain for all of the
computers in the local network. The index '001' was selected freely and
is only intended to enhance the overview. The wildcards '?' (stands for
exactly one character) and '*' (for a random number of characters) are
valid when entering the domain. For example, if only a single computer
(IP 10.0.0.123) is to be prohibited from accessing DE-domains, enter:
set 002 *.de 10.0.0.123 255.255.255.255
The hit list in the DNS statistics contains the 64 most frequently requested
names and provides a good basis for setting up the filter list.
If your LAN uses subnetting, you can also apply filters to individual
departments by carefully selecting the IP addresses and subnet masks.
The IP address '0.0.0.0' stands for all computers in the network, and the
subnet mask '0.0.0.0' for all networks.
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4.10 NetBIOS proxy
With the NetBIOS proxy function, a ELSA LANCOM DSL/25 Office can also
route NetBIOS packets or respond locally as a proxy. As a result, it is now
possible to economically link Microsoft Networks using the router function.
This section describes the general functions of NetBIOS proxy, as well as the
configuration of the router and workstations for the interconnection of
Microsoft Networks.
4.10.1 To the point: What is NetBIOS?
NetBIOS provides a simple, trouble-free means of networking multiple
computers. An important example for NetBIOS networks is the Microsoft
Network, with which several Windows 3.11, 9x and NT workstations can be
networked simply by sharing the resources (drives or printers) of the
individual computers with the other participants.
In a Microsoft Network, the computers are only addressed via their names.
Multiple computers can be organized into groups, and multiple groups can be
grouped further as scopes. The names used must be known throughout the
network for all computers to be able to access the resources of the others.
NetBIOS computers issue their names into the network at regular intervals to
eliminate the necessity of maintaining tables of known names on each
computer.
The names publicized in this manner should, of course, be collected and made
available at a central location in the Microsoft Network. If two Microsoft
Networks are to be connected using a router, then such a name collection
point, a so-called NetBIOS nameserver (NBNS), must be present on both
sides.
A WINS server (Windows Internet Name Service Server) can be installed
in the network for this purpose.
However, a second option is also available, since many Microsoft
Networks can or must make do without a server of their own: Information
about the names in use can be placed on a “billboard” of sorts, on which
all participating computers only post their names and IP addresses. In
this case, the individual computers are responsible for the consistency of
their names within the network.
The ELSA LANCOM DSL/25 Office offers such a billboard. The interconnec-
tion of Microsoft Networks is thus possible without a server as a result of this
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simple realization of the NBNS. The computers in the networks to be inter-
connected thus publicize their names and add them to the billboards in the
respective remote networks.
4.10.2 Handling of NetBIOS packets
The highly verbose nature of Windows computers can result in high charges
for dial-up connections, as each NetBIOS packet containing name
information automatically launches a call establishment (e.g. to a previously
set up ISP). The connection remains permanently established due to these
packets, resulting in high connect charges without the transfer of actual user
data.
An ELSA LANCOM DSL/25 Office can either route or spoof the NetBIOS
packets to prevent the establishment of unnecessary connections:
In the NetBIOS module, it is possible to specify the remote stations to
which the name information should be transferred via NetBIOS to ensure
the routing of those packets that are actually required. After the NetBIOS
module has been switched on and an unspecified waiting time has
elapsed, a connection is established to the NetBIOS remote stations
(insofar as these are not individual Remote Access workstations). The
duration of the waiting period will be increased if the connection cannot
be established. The following exchange of NetBIOS information then fills
the billboard for the first time.
In its proxy function, the unit answers queries to computers already
known in the NetBIOS module (on the billboard) by proxy for those
computers. After the initial exchange of information, no new connections
are established as a result of queries to workstations in the local
network, or to known workstations in the remote network.
The preset IP filter for NetBIOS ports intercepts packets with queries for
stations not present in either the LAN, or as established NetBIOS remote
stations, thus preventing the establishment of a connection via the DEFAULT
route to the Internet.
4.10.3 Which preconditions must be fulfilled?
A number of components must be installed on the participating workstations
and a variety of settings made in the operating system to ensure correct
communications via routers for the interconnection of Microsoft Networks.
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Installed components
The installation of the required components will be illustrated here on the
basis of Windows 95 or Windows 98; the procedure for Windows NT 4.0 is
similar. Install the following components on all workstations in the Microsoft
Networks to be interconnected:
Network protocol
NetBIOS is completely independent of the transport protocol used.
NetBIOS network data can thus be transferred using the NetBEUI
(NetBIOS Extended User Interface), IPX (Internet Packet eXchange,
Novell) or IP (Internet Protocol) protocols.
Unlike IPX and IP, NetBEUI is not routable and is thus only available in
Microsoft Networks. If multiple Microsoft Networks are to be interconnected
using routes, NetBIOS must be based on a ratable protocol in the ELSA
LANCOM DSL/25 Office, such as IPA.
The routing of NetBIOS packets in the ELSA LANCOM DSL/25 Office is
based on TCP/IP due to its superior filter mechanisms. This protocol must
therefore be installed on all participating workstations.
To install the network protocol, click Start Settings Control Panel
Network Add... Protocol. Select the manufacturer 'Microsoft'
and the 'TCP/IP' network protocol.
Client
The Microsoft Network client is required to permit all of the workstations
in the Microsoft Network to log on with names and passwords.
To install the client, click Start Settings Control Panel
Network Add... Client. Select the manufacturer 'Microsoft' and
the 'Client for Microsoft Networks'.
Service
File and printer sharing permits drives and printers to be shared with
other users in the Windows Network.
To install file and printer sharing, click Start Settings Control
Panel Network Add... Service. Select the manufacturer
'Microsoft' and 'File and printer sharing for Windows Networks'.
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Windows Network settings
Name and group designation
Click Start Settings Control Panel Network and switch to
the Identification tab.
The name of the workstation must be unique. That applies to all
Windows Networks, and all groups that you intend to connect using
NetBIOS within these networks. Names also may not recur in different
groups.
File and printer sharing
Ensure that file and printer sharing is enabled after the installation is
complete. To do so, select Start Settings Control Panel
Network File and Print Sharing.... Specify whether other users in
the Windows Network should be allowed access to the printer and/or
files of this workstation.
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All users intending to access shared resources must log on with their
names and passwords when booting Windows.
In the Windows Explorer, right-click the drives, folders or printers that
you would like to share with others on the network and select the item
Sharing from the context menu.
Enter a name for the shared resource and a description if required. The
manner in which the resource can be accessed can be selected under
Access Type, and by entering passwords as required.
It's easy to check whether the Windows Network settings have been made
correctly: the local computer must appear with its name in the Network
Neighborhood.
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4.10.4 Linking two Windows Networks
Two Windows Networks can be interconnected once these preparations
have been completed. The settings for Workgroup Networks and Domain
Networks (Windows NT) are similar. The following steps must be performed
for both sides of the connection.
Set up both networks for a LAN-LAN interconnection via TCP/IP as
described in the Workshop. We recommend using the convenient ELSA
LANconfig wizard.
Check the settings of the IP filter. This filter must capture all NetBIOS
packets to be sent over the DEFAULT route to ensure that they do not lead
the establishment of a connection on the DEFAULT route. This has been
preset in the unit's factory defaults.
Next, enter the remote station for routing via NetBIOS. Change over to
the ELSA LANconfig 'NetBIOS' configuration section and create a new
entry in the 'NetBIOS over IP Routing table'.
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Alternatively, enter the following when configuring via telnet:
cd /Setup/NetBIOS-module/Remote-table
set nhamel.mobil router
The entry in the 'Type' field specifies whether a connection to the remote
station should be dialed up to exchange name information after
switching on the NetBIOS module.
The 'NT-domain' parameter can generally be left blank in the case of
Windows 95 or 98 networks. The corresponding domain and/or workgroup
must be entered manually when accessing Windows NT machines.
If the NetBIOS link uses a PPP connection, check the PPP list for the
activation of NetBIOS for the corresponding entry.
Once all remote stations have been entered, activate the NetBIOS
function.
cd /Setup/NetBIOS-module
set operating on
After switching the module on, a connection is established after an
unspecified waiting time to all remote stations not identified as dial-up
nodes. The required information regarding the other computers in the
networks is then exchanged during this initial connection. Computers on
the remote site cannot be accessed until this operation is complete.
4.10.5 Dial-up procedure for a remote access station
Accessing a Windows Network with a single computer via remote access can
also be taken care of quickly.
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The ELSA LANCOM DSL/25 Office and the remote access computer must
be prepared for network access as described in the Workshop. In this
case as well, check the IP filters in the ELSA LANCOM DSL/25 Office (See
'Connecting two Windows networks').
A route must also be entered in the IP routing table if the assignment of
the IP address for the remote station is realized from the IP pool.
Also create an entry for the remote stations in the NetBIOS IP routing
table.
cd /Setup/NetBIOS-module/Remote-table
set nhamel.ras workstation
Be sure to identify this entry as an 'individual station' to ensure that this
remote station is not automatically contacted when the NetBIOS module is
switched on.
If the NetBIOS link uses a PPP connection, check the PPP list for the
activation of NetBIOS for the corresponding entry.
4.10.6 Search and find: the Network Neighborhood
Once the participants have all been prepared for NetBIOS routing, it's time to
launch Windows Networking.
NetBIOS routing via LAN-LAN coupling
Once the NetBIOS modules have been activated and the networks have
exchanged their information regarding the available workstations, a list of
these computer names is now available in the ELSA LANCOM DSL/25 Office.
Using telnet, enter
dir /Setup/NetBIOS-module/Host-list
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to call up the list of currently available workstations, which could look like the
following:
This table shows, for example, that the computer named 'DOKUNOTEBOOK'
with the IP address '10.10.0.53' is available via the remote station
'NHAMEL.MOBIL'. The further parameters are covered in the description of
the menus.
To access the shared resources of this computer, simply use the Windows
Explorer to search for it with Start Find Computer...:
The workgroups and computers of the remote network cannot be found in the
'Explore Entire Network' function of the Windows Network Neighborhood for
technical reasons. Instead, search for remote computers and create
associations as described above.
NetBIOS routing via RAS
The procedure for access to the Windows Network via RAS is somewhat
different. These are the two fundamental differences to LAN-LAN
interconnection:
Name Type IP address Remote site Timeout Flags
DOKUNOTEBOOK 00 10.10.0.53 NHAMEL.MOBIL 4939 0020
DOKUNOTEBOOK 20 10.10.0.53 NHAMEL.MOBIL 4939 0020
ELSA 1d 10.10.0.53 NHAMEL.MOBIL 4939 0020
ELSA.DOKU 1d 10.1.253.246 4935 0000
ELSA.DOKU 1d 192.168.100.1
62
4997 0000
NHAMEL.MOBIL 00 10.10.0.1 NHAMEL.MOBIL 0 0020
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A host list with the computers in the Windows Network is not available
on the dial-up node side. RAS users must know the names of the
computers that they intend to access and for which they have access
rights.
The connection is not established automatically. RAS users must first
establish a connection to the ELSA LANCOM DSL/25 Office via Dial-up
Networking.
Once the connection has been established, RAS users can access computers
in the remote network (using Find Computer..., not the Network
Neighborhood!) in the same way as with the LAN-LAN interconnection.
4.11 ELSA CAPI Faxmodem
The ELSA CAPI Faxmodem provides a Windows fax driver (Fax class 1) as an
interface between the ELSA LANCAPI and applications, permitting the use of
standardfax programs with an ELSA LANCOM DSL/25 Office.
4.11.1 Installation
The ELSA CAPI Faxmodem can be installed from the CD setup. Always install
the ELSA CAPI Faxmodem together with the current version of ELSA
LANCAPI. After restarting, the ELSA CAPI Faxmodem will be available to your
system. Under Windows 95 or Windows 98, it can be found under Start
Control Panel Modems.
4.11.2 Faxing with the ELSA CAPI Faxmodem
Most major fax programs recognize the ELSA CAPI Faxmodem automatically
during installation and identify it as a 'Class 1' fax modem. Fax transmissions
can thus be realized at speeds of up to 14,400 bps. If your fax program offers
you a choice (such as WinFax and Talkworks Pro), select the option 'CLASS 1
(Software Flow Control)' when setting up the modem.
The ELSA CAPI Faxmodem requires ELSA LANCAPI for the transmission of fax
messages. A small CAPI icon in the lower right corner of your screen confirms
that LANCAPI is enabled. Please also take care with the settings of the
LANCAPI itself.
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4.12 Office communications and LANCAPI
LANCAPI from ELSA is a special version of the popular CAPI interface. CAPI
(Common ISDN Application Programming Interface) establishes the
connection between ISDN adapters and communications programs. For their
part, these programs provide the computers with office communications
functions such as a fax machine or answering machine.
This chapter briefly introduces you to LANCAPI and the accompanying
application programs for office communications as well as providing you with
instructions that are important for installing the individual components.
4.12.1 ELSA LANCAPI
What are the advantages of LANCAPI?
Above all, the use of LANCAPI offers you economic advantages. LANCAPI
provides all workstations integrated in the LAN (local area network) with
unlimited access to office communications functions such as fax machines
and EuroFileTransfer. All functions are supplied via the network without the
necessity of additional hardware at each individual workstation, thus
eliminating the costs of equipping the workstations with ATM adapters. All
you need do is install the office communications software on the individual
workstations.
For example, faxes are sent by simulating an fax machine at the workstation.
With the LANCAPI, the PC forwards the fax via the network to the router
which establishes the connection to the recipient.
Installing the LANCAPI client
The LANCAPI is made up of two components, a server (in the ELSA LANCOM
DSL/25 Office) and a client (on the PCs). The LANCAPI client must be
installed on those computers in the LAN that will be using the LANCAPI
functions.
Place the ELSA LANCOM CD in your CD-ROM drive. If the setup program
does not automatically start when you insert the CD, simply click
'autorun.exe' on the ELSA LANCOM CD in the Windows Explorer.
Select the 'Install LANCOM software' entry.
Highlight the 'ELSA LANCAPI' option. Click Next and follow the
instructions for the installation routine.
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If necessary, the system is restarted and LANCAPI is then ready to accept all
jobs from the office communications software. After successful installation,
an icon for LANCAPI will be available in the Start Menu. A double-click on
this icon opens a status window that permits current information on the
LANCAPI to be displayed at any time.
Configuring the LANCAPI client
The configuration of the LANCAPI client is used to determine which LANCAPI
servers will be used and how these will be checked. All parameters can
remain at their default settings if you are using only one ELSA LANCOM
DSL/25 Office in your LAN as a LANCAPI server.
Start the LANCAPI client in the 'ELSAlan' program group. Information
regarding the drivers for the available service can be found on the
'General' tab.
Switch to the 'LANCAPI Server' tab. First, select whether the PC should
find its own LANCAPI server, or specify the use of a particular server.
For the former, determine the interval at which the client should
search for a server. It will continue searching until it has found the
number of servers specified in the next field. Once the required
number of servers has been found, it will stop searching.
In the event that the client should not automatically search for
servers, list the IP addresses of the servers to be used by the client.
This can be useful if you are operating several ELSA LANCOM DSL/25
Office in your LAN as LANCAPI servers and you would like to specify
a server for a group of PCs, for example.
It is also possible to set the interval at which the client checks
whether the found or listed servers are still active.
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Configuring the LANCAPI server
Two basic issues are important when configuring the LANCAPI server:
What call numbers from the telephone network should LANCAPI respond
to?
Which of the computers in the local network should be able to access the
telephone network via LANCAPI?
Set the relevant parameters as follows:
Start ELSA LANconfig which can be found in the 'ELSAlan' program
group. Open the configuration of the router by double-clicking on the
device name in the list and select the 'LANCAPI' section.
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Activate the LANCAPI server, or set it to permit outgoing calls only. In the
latter case, the LANCAPI will not respond to incoming calls—to receive
faxes, for example. Permitting outgoing calls only is useful if you do not
have a specific call number available for the LANCAPI.
When the LANCAPI server is activated, enter the call numbers to which
the LANCAPI should respond in the 'Number' field. You can enter several
call numbers separated by semicolons. If you do not enter a call number
here, all incoming calls are reported to LANCAPI.
LANCAPI is preset to use port '75' (any private telephony service). Do not
change this setting unless this port is already in use by a different service
in your LAN.
If you do not wish all the computers in the local network to be able to
access the LANCAPI functions, you can define all the authorized users (by
means of their IP addresses) by entering them in the access list.
If you enter more than one call number for the LANCAPI, you can, for example,
provide each individual workstation with a personal fax machine or personal
answering machine. Proceed as follows: When installing communications
programs such as ELSA-RVS-COM on the different workstations, specify the
various call numbers to which the program should respond.
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Switch to the 'availability' tab. Here you can determine how the ELSA
LANCOM DSL/25 Office should respond if a connection is to be established
via the LANCAPI (incoming or outgoing) when both B channels are already
busy (priority control). The available options are:
The connection cannot be established via the LANCAPI. A fax program
using the LANCAPI will then probably attempt to send again at a later
time.
The connection via the LANCAPI can then be established when a main
channel is free. A main channel is the first B channel used when a router
connection is established. Secondary channels are used for channel
bundling.
A connection can always be established via the LANCAPI; an existing
router connection will be terminated for the duration of the call if
required. This can be used to ensure the permanent availability of the fax
function, for example.
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Using the LANCAPI
Two options are available for the use of the LANCAPI:
You may use software which interacts directly with a CAPI (in this case,
the LANCAPI) port, such as ELSA-RVS-COM. This type of software
searches for the CAPI during its installation and uses it automatically.
Other programs such as LapLink can establish a variety of connection
types, for example, using Windows Dial-up Networking. You may select
the installed communications device that you would like to use when
creating a new dial-up connection. For the LANCAPI, select the entry
'ISDN WAN Line 1'.
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5
Appendix
5.1 Technical data
Functions IP router, DHCP server, DHCP client, DNS server, NetBIOS Proxy, IPX router
LAN connection Ethernet IEEE 802.3, 10/100Base-T (RJ45, node/hub switch), auto-sensing, full duplex
operation
Network protocols IP: ARP, PROXY ARP, IP, ICMP, UDP, TCP, TFTP, RIP-1, RIP-2, DHCP, NetBIOS over IP, DNS,
PPP over ATM, Classical-IP
IPX: IPX, SPX, RIP, SAP, Propagate packets
Filter possibilities Source and target filters for networks, protocols and ports; separate WAN and LAN
WAN interface Ethernet IEEE 802.3, 10Base-T (RJ45), ATM 25.6F
Charge monitoring The maximum charge amount (depending on the provider) or connection time can be
adjusted in a given time period.
Security and firewall
functions
PAP, CHAP and MS-CHAP, PPP authentication mechanisms; filter options in IP mode;
protection of configuration using access lists and passwords, IP masquerading; ATM
protection mechanisms (CLIP, Callback etc.)
IP masquerading
(NAT/PAT)
IP address and port implementation using a single IP address, static/dynamic IP address
assignment via PPP or DHCP, masking of TCP, UDP, ICMP, FTP; DNS forwarding; inverse
masquerading Intranet IP services such as web server; NetBIOS masquerading
Management V.24/V.28 outband interface (8-pin mini-DIN), TFTP configuration and firmware upload,
SNMP management via SNMP v.1 or v.2, WAN or LAN accesses can be activated
separately, diagnosis outputs for protocols and interfaces, diagnosis tools, status display
ELSA LANmonitor, remote configuration via PPP
Operating security Hardware watchdogs, regular self-testing, FirmSafe concept for remote software
upgrades
Statistics LAN and WAN packet counters; error, connection and charge counters
Display/operation LEDs for LAN, WAN and device status
Power supply 12 VA with AC adapter for 230 V, 12 VA
Ambient conditions Temperature: 5-40°C, humidity: 0-80%, non-condensing
Dimensions and design Rugged metal case, connections on rear panel; dimensions 158 x 40 x 125 mm
(W x H x D)
Package contents Power adapter, cable for outband interface, ATM line connection cable, LAN twisted-pair
cables, complete documentation
Approvals CE: EN 55022, EN 55024 and EN 60950; T-Nova: 1269510198 and E.000009.07.01
Service
Support
Warranty: 6 years
Via infoline and Internet
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5.2 Warranty conditions
The ELSA AG warranty, valid as of June 01, 1998, is given to purchasers of ELSA products in
addition to the warranty conditions provided by law and in accordance with the following
conditions:
1 Warranty coverage
a) The warranty covers the equipment delivered and all its parts. Parts will, at our sole
discretion, be replaced or repaired free of charge if, despite proven proper handling and
adherence to the operating instructions, these parts became defective due to fabrication
and/or material defects. Also we reserve the right to replace the defective product by a
successor product or repay the original purchase price to the buyer in exchange to the
defective product. Operating manuals and possibly supplied software are excluded from
the warranty.
b) Material and service charges shall be covered by us, but not shipping and handling costs
involved in transport from the buyer to the service station and/or to us.
c) Replaced parts become property of ELSA.
d) ELSA are authorized to carry out technical changes (e.g. firmware updates) beyond repair
and replacement of defective parts in order to bring the equipment up to the current
technical state. This does not result in any additional charge for the customer. A legal claim
to this service does not exist.
2 Warranty period
The warranty period for ELSA products is six years. Excepted from this warranty period are ELSA
monitors and ELSA videoconferencing systems with a warranty period of 3 years. This period
begins at the day of delivery from the ELSA dealer. Warranty services do not result in an
extension of the warranty period nor do they initiate a new warranty period. The warranty period
for installed replacement parts ends with the warranty period of the device as a whole.
3 Warranty procedure
a) If defects appear during the warranty period, the warranty claims must be made
immediately, at the latest within a period of 7 days.
b) In the case of any externally visible damage arising from transport (e.g. damage to the
housing), the transport company representative and ELSA should be informed immediately.
On discovery of damage which is not externally visible, the transport company and ELSA are
to be immediately informed in writing, at the latest within 7 days of delivery.
c) Transport to and from the location where the warranty claim is accepted and/or the repaired
device is exchanged, is at the purchaser's own risk and cost.
d) Warranty claims are only valid if the original purchase receipt is returned with the device.
4 Suspension of the warranty
All warranty claims will be deemed invalid
a) if the device is damaged or destroyed as a result of acts of nature or by environmental
influences (moisture, electric shock, dust, etc.),
b) if the device was stored or operated under conditions not in compliance with the technical
specifications,
c) if the damage occurred due to incorrect handling, especially to non-observance of the
system description and the operating instructions,
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d) if the device was opened, repaired or modified by persons not authorized by ELSA,
e) if the device shows any kind of mechanical damage,
f) if in the case of an ELSA Monitor, damage to the cathode ray tube (CRT) has been caused
especially by mechanical load (e.g. from shock to the pitch mask assembly or damage to the
glass tube), by strong magnetic fields near the CRT (colored dots on the screen), or through
the permanent display of an unchanging image (phosphor burnt),
g) if, and in as far as, the luminance of the TFT panel backlighting gradually decreases with
time, or
h) if the warranty claim has not been reported in accordance with 3a) or 3b).
5 Operating mistakes
If it becomes apparent that the reported malfunction of the device has been caused by unsuitable
software, hardware, installation or operation, ELSA reserves the right to charge the purchaser
for the resulting testing costs.
6 Additional regulations
a) The above conditions define the complete scope of ELSA’s legal liability.
b) The warranty gives no entitlement to additional claims, such as any refund in full or in part.
Compensation claims, regardless of the legal basis, are excluded. This does not apply if e.g.
injury to persons or damage to private property are specifically covered by the product
liability law, or in cases of intentional act or culpable negligence.
c) Claims for compensation of lost profits, indirect or consequential detriments, are excluded.
d) ELSA is not liable for lost data or retrieval of lost data in cases of slight and ordinary
negligence.
e) In the case that the intentional or culpable negligence of ELSA employees has caused a loss
of data, ELSA will be liable for those costs typical to the recovery of data where periodic
security data back-ups have been made.
f) The warranty is valid only for the first purchaser and is not transferable.
g) The court of jurisdiction is located in Aachen, Germany in the case that the purchaser is a
merchant. If the purchaser does not have a court of jurisdiction in the Federal Republic of
Germany or if he moves his domicile out of Germany after conclusion of the contract, ELSA’s
court of jurisdiction applies. This is also applicable if the purchaser's domicile is not known
at the time of institution of proceedings.
h) The law of the Federal Republic of Germany is applicable. The UN commercial law does not
apply to dealings between ELSA and the purchaser.
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5.3 Declaration of conformity
KONFORMITÄTSERKLÄRUNG
DECLARATION OF CONFORMITY
Diese Erklärung gilt für folgendes Erzeugnis:
This declaration is valid for the following product:
Geräteart: ATM Router
Type of Device:
Typenbezeichnung: LANCOM DSL/25 Office
Product Name:
Hiermit wird bestätigt, daß das Erzeugnis den folgenden Schutzanforderungen entspricht:
This is to confirm that this product meets all essential protection requirements relating to the
Niederspannungs Richtlinie (73/23/EWG)
Low Voltage Directive (73/23/EEC)
EMV Richtlinie (89/336/EWG)
EMC Directive (89/336/EEC)
Zur Beurteilung der Konformität wurden folgende Normen herangezogen:
The assessment of this product has been based on the following standards
EN 50081-1: 1992 Teile/
parts
: EN 55022: 1994
EN 50082-1: 1997 Teile/
parts
: EN55024: 1999
EN 60950: 1992+ A1: 1993 +A2: 1993 +A3: 1995 +A4: 1996
Diese Erklärung wird verantwortlich für den Hersteller / Importeur:
On behalf of the manufacturer / importer:
ELSA AG
Sonnenweg 11
D-52070 Aachen
abgegeben durch: /
this declaration is submitted by:
Aachen, 23. August 1999
Aachen, 23
rd
August 1999
i.V. Stefan Kriebel
Bereichsleiter Entwicklung
VP Engineering
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6 Index
!
10/100Base-TX
...................................23
100 Mbit network
...............................23
A
Access control
....................................48
Access protection
........................ 14, 49
name
...............................................49
name or number
..............................49
number
............................................49
Access Type
........................................ 96
Adapter
...............................................34
Adapter for configuration cable
.........17
Address Administration
......................35
address administration
.......................80
Address pool
................................ 82, 87
ATM cable
..........................................12
ATM connection cable
........................ 17
ATM interface
.....................................12
ATM network
......................................12
ATM-25.6
............................................23
Authentication
....................................60
authentication
.....................................14
Availability
........................................106
Available workstations
.....................100
B
Barring
................................................48
Brute force
................................... 14, 48
C
Call charge limit
..................................51
Call charge management
....................51
Call establishment
..............................93
Callback
....................................... 11, 50
fast call back
...................................51
CAPI Faxmodem
................................101
CAPI interface
................................... 102
CD
....................................................... 17
Challenge Handshake Authentication
Protocol
...............................................50
CHAP
................................................... 50
Charge monitoring
..............................14
Classical IP
..........................................12
Common ISDN Application Programming
Interface
............................................ 102
Computer names
.......................... 88, 92
Configuration
...................................... 13
methods
.......................................... 33
SNMP
..............................................46
Configuration interface
................ 17, 33
Connect charges
.................................93
Connection duration
...........................14
Connections
........................................ 23
Cost reduction
.....................................51
D
Data transfer in the IPX network
........ 64
Dedicated lines
...................................11
DHCP
................................................... 80
DHCP for WINS Resolution
................ 85
DHCP mode
.........................................81
DHCP server
....................15, 35, 81, 88
configuration
...................................86
Dial-up connection
....................... 11, 37
Dial-Up Networking
............................ 50
Distance of a route
.............................70
DNS
.............................................. 79, 88
DNS Forwarding
................................. 79
DNS forwarding mechanism
..............89
DNS server
......................15, 80, 83, 88
available information
......................89
filter list
..........................................91
filter mechanism
.............................89
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Documentation ...................................17
Domain Name Service
..................79, 88
Domains
..............................................88
Dynamic Host Configuration Protocol
81
Dynamic routing
..................................69
E
Electronic documentation
...................17
ELSA CAPI Faxmodem
........................15
ELSA-RVS-COM
..................................11
ELSA-ZOC
............................................11
E-mail
..................................................10
End address
........................................82
Ethernet
10/100Base-T
..................................12
Fast Ethernet
...................................12
EuroFileTransfer
........................... 10, 15
Exclusion routes
..................................70
F
Fast Call Back
.....................................51
Fast Ethernet
.......................................12
Fast-Ethernet
10/100Base-T
..................................12
Fax
.................................10, 11, 15, 101
Fax Class 1
........................................101
Fax driver
..........................................101
Fax transmission
...............................101
Faxmodem
...........................................15
LANCAPI
........................................101
File and printer sharing
.......................94
File transfer
.........................................10
Filter
....................................................49
Filter mechanisms
...............................11
Firewall
...............................................14
Firewall function
.................................51
FirmSafe
....................................... 13, 40
Firmware
.............................................13
Firmware upload
.................................41
using TFTP
.......................................42
with LANconfig
...............................41
with terminal program
.................... 42
fixed connections
................................ 12
Flash ROM
....................................13, 40
G
Gateway
.................................51, 80, 84
Groups
.................................................92
H
High telephone costs
.......................... 51
Home office
........................................ 11
Host
.....................................................88
Hyperterminal
..................................... 34
I
Identification
.......................................95
Identifying the caller
...........................49
Inband
.......................................... 33, 34
using telnet
..................................... 36
Inband configuration
...........................33
Install software
................................... 40
Installation
..........................................12
Interfaces
............................................ 23
Internet
........................................ 10, 51
Internet address
.................................. 77
Internet service provider
..................... 10
IP access list
.......................................34
IP address
.............................. 15, 35, 51
IP filter
................................................ 93
IP masquerading
.............10, 14, 49, 77
simple masquerading
.....................78
supported protocols
........................ 79
IP routing
Filter
................................................ 72
FTP
.................................................. 72
telnet
...............................................72
IP routing table
...................................69
IP via ATM
.......................................... 12
IPX addressing
.................................... 61
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IPX routing
backoff
............................................63
binding
..................................... 62, 63
exponential backoff
........................65
filters
...............................................66
hops
................................................. 64
loop-propagating
.............................65
network
...........................................63
propagate
........................................ 63
remote station
.................................62
RIP and SAP tables
.........................64
tics
...................................................64
IPX watchdogs
....................................68
IPX-routing-table
................................. 62
K
Key
......................................................60
L
LAN connection
..................................12
LAN connection cable
.........................17
LAN link
..............................................22
LAN to LAN coupling
..........................11
LANCAPI
................ 10, 11, 15, 37, 102
LANCAPI client
.................................102
LANCAPI server
................................104
LAN-coll
..............................................22
LANconfig
......... 24, 34, 35, 37, 41, 43
LANmonitor
.................................. 14, 43
LAN-rx
.................................................22
LAN-tx
.................................................22
LCP echo reply
....................................61
LCP echo request
................................61
LED
......................................................21
LED indicators
.....................................14
Line connection
...................................15
Line management
........................ 11, 15
Login
............................................ 41, 48
Login barring
.......................................48
M
Mail server
..........................................91
Microsoft Network
.............................92
Microsoft Network client
................... 94
Mode
...................................................81
Monitoring
..........................................43
MS-CHAP
..................................... 58, 59
N
Name and group designation
............. 95
Name information
...............................93
Names
.................................................92
NAT
........................................49, 51, 77
NBNS
.................................................. 92
NBNS server
..........................80, 83, 85
NetBIOS
....................................... 16, 89
IP filter
............................................ 97
LAN-LAN interconnection
............... 97
network protocol
............................. 94
remote access
.................................98
remote station
................................ 97
TCP/IP
.............................................94
NetBIOS nameserver
.......................... 92
NetBIOS networks
..............................89
NetBIOS ports
..................................... 93
NetBIOS proxy
.................................... 92
NetBIOS remote stations
...................93
Network connection
...........................10
Network Information Center
.............. 77
Network names
..................................88
Network Neighborhood
......................99
NIC
......................................................77
Node/hub selector switch
..................23
O
Office communications
.....................102
Online media
.......................................34
Online minutes
.................................... 51
Operating modes
................................ 47
Outband
..............................................33
20659_DE_0300.book Seite 115 Mittwoch, 17. Mai 2000 9:19 09
Index
|
|
ELSA LANCOM DSL/25 Office
|
116
EN
Requirements ..................................34
Outband configuration
........................34
P
Package contents
................................17
PAP
......................................................50
Password
................. 39, 44, 49, 50, 96
Password Authentication Protocol
.....50
Password protection
.................... 14, 47
PAT
.........................................49, 51, 77
Peer-to-peer networks
........................16
Period
..................................................51
Period of validity
.......................... 81, 84
Permanent Virtual Connection
............ 12
Port
....................................................105
Port number
........................................79
Power
..................................................22
Power supply unit
........................ 17, 23
PPP
.........................................12, 16, 50
checking the line with LCP
..............61
PPP client
............................................37
PPP connection
...................................38
PPP list
................................................49
PPP negotiation
...................................39
priority control
..................................106
Prohibiting domains
............................ 91
Propagated frames
.............................66
Proxy
...................................................16
PVC
......................................................12
R
Remote Access
...................................93
Remote access
............................. 11, 37
Remote configuration
.........................16
Remote connection
.............................37
RIP
.......................................................64
RIP tables
............................................64
Router name
.......................................70
Routing
................................................93
routing information protocol
...............64
Routing Microsoft Networks
.............. 92
S
SAP
..................................................... 64
SAP tables
.......................................... 64
Scopes
................................................ 92
Security
..................................47, 49, 51
Security features
................................ 10
Security procedures
............................ 50
Serial port
...........................................33
Service
................................................ 88
service advertising protocol
............... 64
Shared resources
................................ 96
Sharing
................................................ 96
Single user access
..............................51
SNMP
..................................................46
Socket filter
........................................ 67
Software update
.................................13
Split horizon
........................................ 65
SPX watchdogs
...................................68
Standard fax programs
.....................101
Start address
......................................82
Static routing
...................................... 69
Statistics
.............................................14
Status Displays
...................................14
SVC
..................................................... 12
Switched Virtual Connection
.............. 12
T
TCP/IP
....................................24, 35, 68
TCP/IP networks
................................. 88
Technical data
.................................. 109
Teleworking
........................................ 11
Telix
.................................................... 34
Telnet
........................................... 13, 37
Terminal program
........................ 13, 34
TFTP
.................................................... 35
Time limit
............................................ 52
Trace
code and parameters
......................45
20659_DE_0300.book Seite 116 Mittwoch, 17. Mai 2000 9:19 09
|
Index
117
|
ELSA LANCOM DSL/25 Office
|
EN
Examples ......................................... 46
starting
............................................44
Trace outputs
......................................44
Transfer costs
.....................................16
Transmission rates
.............................14
Troubleshooting
..................................43
Type of Service
...................................80
U
Upload
.......................................... 13, 40
User name
..............................39, 50, 60
V
V.24 configuration interface
...............23
Voice mail
...........................................11
W
WAN connection
................................ 12
Watchdogs
..........................................68
Wildcards
............................................ 91
Windows Internet Name
Service Server
..................................... 92
Windows network
.............................. 85
Windows Networking
.........................99
Windows networks
.............................16
winipcfg
..............................................25
WINS Address
.................................... 85
WINS server
.......................................92
WWW
................................................. 51
20659_DE_0300.book Seite 117 Mittwoch, 17. Mai 2000 9:19 09
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