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Glossary

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SNA

System Network Architecture: A complex, feature-rich, network

architecture similar to the OSI reference model but with several variations;
created by IBM in the 1970s and essentially composed of seven layers.

SNAP

Subnetwork Access Protocol: SNAP is a frame used in Ethernet,

Token Ring, and FDDI LANs. Data transfer, connection management, and
QoS selection are three primary functions executed by the SNAP frame.

snapshot routing

Snapshot routing takes a point-in-time capture of a

dynamic routing table and maintains it even when the remote connection
goes down. This allows the use of a dynamic routing protocol without
requiring the link to remain active, which might incur per-minute usage
charges.

socket

1) A software structure that operates within a network device as a

destination point for communications. 2) In AppleTalk networks, an entity
at a specific location within a node; AppleTalk sockets are conceptually sim-
ilar to TCP/IP ports.

SOHO

small office, home office: A contemporary term for remote users.

SONET

Synchronous Optical Network: The ANSI standard for synchro-

nous transmission on fiber-optic media, developed at Bell Labs. It specifies a
base signal rate of 51.84Mbps and a set of multiples of that rate, known as
Optical Carrier levels, up to 2.5Gbps.

source trees

A method of multicast data forwarding. Source trees use the

architecture of the source of the multicast traffic as the root of the tree.

Switch Processor: Also known as a ciscoBus controller, it is a Cisco 7000

series processor module acting as governing agent for all CxBus activities.

span

A full-duplex digital transmission line connecting two facilities.

SPAN

Switched Port Analyzer: A feature of the Catalyst 5000 switch,

offering freedom to manipulate within a switched Ethernet environment by
extending the monitoring ability of the existing network analyzers into the
environment. At one switched segment, the SPAN mirrors traffic onto a pre-
determined SPAN port, while a network analyzer connected to the SPAN
port is able to monitor traffic from any other Catalyst switched port.

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