Cabletron Systems STS16-20R - Manual (Page 44)

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SmartStack STS16-20D/STS16-20R Token Ring Switches Installation and User Guide Switch Overview
For details about CrossLink configuration, please refer to the section “CrossLink”
on page 110 in Chapter 6, “Switch Configuration”.
Spanning Tree Protocol Support
IBM initially supported only source route bridging (SRB) in its bridges, so most
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 source route transparent bridges. The IEEE
Spanning Tree Protocol is not compatible with the IBM Spanning Tree Protocol.
The SmartStack STS16-20D/STS16-20R supports both the IEEE 802.1D Spanning
Tree Protocol and IBM Spanning Tree Protocols.
➽ Note: On SmartStack STS16-20D only the network ports 17–20 support the
spanning tree protocol at the port level.