Operations Manual
131
SONET—See Synchronous Optical Network.
STANDALONE—Repeater operating as a hub on its own; i.e., not a module among
other modules in a department concentrator chassis.
STRAIGHT-THROUGH—A type of wiring connection where the pins of one connector
connect to the same pins of another connector. For example, pin 1 of one connector
connects to pin 1 of another connector.
STRAIGHT TIP (ST) CONNECTOR—A type of port connection where the pins
connect through a bayonet-style interface.
SUBSCRIBER CHANNEL (SC) CONNECTOR—A type of port connection where the
pins connect through a push-pull mating interface.
SUB MINIATURE ASSEMBLY (SMA) CONNECTOR —A type of port connection
where the pins connect through a threaded attachment interface. Also referred to as an
SM Connector.
SWITCH, ETHERNET—A type of Ethernet hub that filters traffic based on low-level
address. As over against a repeater, a switch does not necessarily broadcast, retime or
retransmit packets, depending on its configuration. A switch cuts down on traffic by
placing packets only on the receiver’s segment when known.
SWITCHED VIRTUAL CIRCUIT (SVC)—A virtual circuit (X.25), virtual connection
(Frame Relay) or virtual channel connection (ATM) that has been established
dynamically in response to a signaling request message.
SWITCHED LAN—Emerging technology that replaces the shared bus backplane of
Ethernet hubs and the shared ring backplane of token Ring hubs with a switching
backplane. Connectivity is provided by switching sender traffic directly to the port of the
addressed destination device. Provides potentially higher throughput, scalable capacity,
and simpler configuration support. Does not require any changes to access wiring or
adapter cards.
SYNCHRONOUS OPTICAL NETWORK (SONET)—A set of physical layer
definitions for data transmission across fiber-based high-speed links. Two options are
available for the Fiber Optic ATM interface: Synchronous Optical Network (SONET)
STS-3c-type framing (which is more common in North America) and Synchronous
Digital Hierarchy (SDH-1) framing (which is more common in other countries).
Whichever option you choose should remain consistent throughout the entire network.
TCP/IP PROTOCOLS—A set of protocols for intercomputer communication, including
network level (Internet Protocol), transport level (Transmission Control Protocol or
TCP) and application level protocols (for example, Telnet terminal emulation). TCP/IP
has been used for many years in two country-wide networks, the ARPANET and
MILNET. Recently, TCP/IP has become very popular with users of a variety of multi-
user computer systems and engineering workstations. Most UNIX computers use TCP/
IP over Ethernet as the main intercomputer networking technology. TCP/IP is also
popular among PC users, particularly as a means of communication with large multi-
user computers.
TIME DIVISION MULTIPLEXING (TDM) — This is a technique that combines
several channels onto one high-speed circuit by providing each channel a specific,
regularly recurring time slot sufficsient to carry the full transmission rate of that
channel. The transmixsion rate of the the high-speed circuit must be equal to, or greater
than, the aggregate speed of all of the channels.
TELCO CONNECTOR— A 50-pin receptacle that plugs into the front of the hub,
enabling cables from external devices to connect to the hub.
TRUNK CABLE—Coaxial cable used for distribution of signals over long distances
throughout a cable system.
