Troubleshooting MSTP operation

Duplicate packets on a VLAN, or packets not arriving on a LAN at all.

The allocation of VLANs to MSTIs may not be identical among all switches in a region.

A switch intended to operate in a region does not receive traffic from other switches in the region.

An MSTP switch intended for a particular region may not have the same configuration name or region revision number as the other switches intended for the same region. The MSTP configuration name (spanning-tree config-name command) and MSTP configuration revision number (spanning-tree config-revision command) must be identical on all MSTP switches intended for the same region.

Another possible cause is that the set of VLANs and VLAN ID-to-MSTI mappings (spanning-tree instance vlan command) configured on the switch may not match the set of VLANs and VLAN ID-to-MSTI mappings configured on other switches in the intended region.