Posts tagged spanning tree
Suspect a loop if you see the following:
You capture traffic on a link and see the same frames multiple times.
All users in a bridging domain have connectivity problems at the same time.
There is abnormally high port utilization.
To remedy a loop quickly, shut redundant ports and then enable them one at a time. Some switches enable debugging of STP to help in diagnosing problems. The following commands are useful for isolating a bridging loop
show spanning tree
show process cpu
debug spanning tree
show mac address-table aging-time vlan#
show spanning-tree vlan vlan# detail
To optimize data flow in the network, design and configure Spanning Tree in the following ways:
Statically configure switches to be the primary and secondary root bridges by setting priority values.
Consider which interfaces will become designated and root ports (possibly set port priorities/path cost).
Tune STP using the tools detailed in this section.
Enable UDLD aggressive mode on all fiber interfaces.
Design STP domains that are as simple and contained as possible by using multilayer switches and routed links.
Use PVRST+ or MST for the fastest convergence times.