Configuring the WSM using Device Manager

Example--four-WSM topology with single spanning tree    

In the following four-WSM topology example, assuming WSM A has the higher priority, you can have at least three loops on the network:

• traffic flowing from WSMs A-B-C-A
• traffic flowing from WSMs A-C-D-A
• traffic flowing from WSMs A-B-C-D-A.

In a single spanning tree environment, depending on the bridge priority, port priority, and port cost, it is possible that the link between WSMs C and D or between WSMs B and C may be blocked. If the block is between WSMs B and C, then the blocked link will inadvertently isolate VLAN 3 altogether.

However, if multiple spanning trees are implemented and each VLAN is on a different spanning tree, then elimination of logical loops will not isolate any VLAN altogether.

See also:

• About Spanning Tree protocol
• VLANs and spanning tree protocol
• Understanding multiple spanning trees
• Why multiple Spanning Trees?
• Example--four-WSM topology with multiple spanning trees
• Multiple spanning tree example--determining root cost
• Root cost comparison
• Configuring spanning tree protocol