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Glossary

software address

Also called a logical address. This is typically an IP

address, but can also be an IPX address.

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 tree

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.

spanning explorer packet

Sometimes called limited-route or single-

route explorer packet, it pursues a statically configured spanning tree when
searching for paths in a source-route bridging network. See also: all-routes
explorer packet, explorer packet, and local explorer packet.

spanning tree

A subset of a network topology, within which no loops

exist. When bridges are interconnected into a loop, the bridge, or switch,
cannot identify a frame that has been forwarded previously, so there is no
mechanism for removing a frame as it passes the interface numerous times.
Without a method of removing these frames, the bridges continuously for-
ward them--consuming bandwidth and adding overhead to the network.
Spanning trees prune the network to provide only one path for any packet.
See also: Spanning Tree Protocol and spanning-tree algorithm.

spanning-tree algorithm (STA)

An algorithm that creates a spanning

tree using the Spanning Tree Protocol (STP). See also: spanning-tree and
Spanning Tree Protocol.

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