multiple spanning tree port roles !!

[mohammed hashim]

hi,

after configuring MST

one of the switches I am not sure why it was showing this when I inserted command "show spann vlan 10"

Fa0/19              Mstr FWD 200000    128.21   P2p Bound(PVST)

however MST was configured on this switch. when I shut the port down and bring it up, it changed to:

Fa0/19              Root FWD 200000    128.21   P2p Pre-STD-Rx 

what is the port role Mstr? and why when I restarted the port it changed to work normally as root.

also the type shows P2p Pre-STD-Rx while other switches are just P2p

[Mark Malone · Accepted solution]

Hi

Is this just a LAB as Pre-STD-Rx means your running mst/rstp that's very old incompatible between switches , it will still work but they should be upgraded to newer IOS versions, You could use this command either under the interface spanning-tree mst pre-standard to force it

The mstr FWD is the master port for the uplink root port usually for the CIST in a multi-region MST operation

[mohammed hashim]

thanks Mark,

[lmediavilla]

I've had that issue when on the same region I had wrong vlan mappings on the same instances in different switches.