Allied Telesis AT-S25 - Manual (Page 155)

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Appendix C
Spanning Tree Protocol Concepts
This appendix provides a brief explanation of the Spanning Tree
Protocol (STP) as implemented by Allied Telesyn on the AT-8300 Series
Fast Ethernet Switches.
For detailed information on the operation of the Spanning Tree Protocol,
consult Section 4 of IEEE Std 802.1D, ISO/IEC 10038: 1993.
The AT-8300 switches, which run the AT-S25 software, implement the
IEEE 802.1D Spanning Tree Protocol. The STP provides a network with
robustness and allows network administrators to easily change their
network topology. Its implementation reduces complex network
topologies (networks with multiple paths between source and
destination nodes) to a single active topology. This technique
guarantees that loops do not occur between source and destination
nodes of the network. Loops are eliminated by placing some of the
redundant ports in a “blocking” state, in which they do not forward
packets but continue to execute the protocol. If the network topology
changes, for example by the failure, removal, or addition of an active
network node, a “blocked” port may be included in the new active
topology and begin forwarding frames.