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34
Spanning Tree Protocol Support
The CrossFire 8730 supports the spanning tree protocols most often used in both
Ethernet and Token-Ring topologies. The switch supports IEEE 802.1D Spanning
Tree for all Ethernet ports, and both IEEE 802.1D Spanning Tree and IBM
Spanning Tree Protocols for Token-Ring ports. This makes it easy to integrate the
switch into most existing Token-Ring and Fast Ethernet installations.
For more information on spanning tree, see "Spanning Tree Configuration for Fast
Ethernet" on page 28 and "Spanning Tree Protocol" on page 64.
IBM initially supported only Source Route Bridging (SRB) in its bridges, so most
Token-Ring networks were built to use it. The main consideration for SRB
implementations in switches is the spanning-tree algorithm for spanning tree
explorers (STEs). IBM originally implemented a form of the Institute of Electrical
and Electronics Engineers (IEEE) spanning-tree algorithm. This algorithm,
commonly referred to as the IBM spanning tree, limits the STE frames to one copy
per destination ring. Some SRB implementations have also implemented the IEEE
Spanning Tree Protocol to be compatible with SRT bridges. The IEEE Spanning
Tree Protocol is not compatible with the IBM Spanning Tree Protocol.
CrossFire 8730 Switch Reference Guide, DOC-7047 v. 1.1
Switch Overview
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