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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.
Spanning Tree Protocol (STP)
The bridge protocol (IEEE 802.1d) that
enables a learning bridge to dynamically avoid loops in the network
topology by creating a spanning tree using the spanning-tree algorithm.
Spanning-tree frames called bridge protocol data units (BPDUs) are sent and
received by all switches in the network at regular intervals. The switches par-
ticipating in the spanning tree don't forward the frames; instead, they're pro-
cessed to determine the spanning-tree topology itself. Cisco Catalyst series
switches use STP 802.1d to perform this function. See also: BPDU, learning
bridge, MAC address, spanning tree,
and spanning-tree algorithm.
Shortest Path First algorithm: A routing algorithm used to decide on
the shortest-path spanning tree. Sometimes called Dijkstra's algorithm and
frequently used in link-state routing algorithms. See also: link-state routing
Service Profile Identifier: A number assigned by service providers or
local telephone companies and assigned by administrators to a BRI port.
SPIDs are used to determine subscription services of a device connected via
ISDN. ISDN devices use SPID when accessing the telephone company switch
that initializes the link to a service provider.
Copyright ©2001 SYBEX , Inc., Alameda, CA