MST (Multiple Spanning Tree) Revision Number

JaCkNiFe

I searched the forum for similar topics regarding MST's configuration revision number and came up empty. I have read Cisco's "Understanding Multiple Spanning Tree Protocol (802.1s)", both CCNP:SWITCH books and employed the Google machine finding little information regarding the revision command except the fact that it must match within an MST region. Also, the revision number does not increment unless you were to increment it manually regardless of added or removed configuration.

A typical MST configuration is as follows:

SW1(config)#spanning-tree mst configuration
SW1(config-mst)#name MST_NAME
SW1(config-mst)#revision 1 <----cmd in question (0-65535)
SW1(config-mst)#instance 1 vlan 10, 30
SW1(config-mst)#instance 2 vlan 20, 40
SW1(config-mst)#exit
SW1(config)#spanning-tree mode mst

My question is, "What purpose does the configuration revision number serve?"

Thanks to any and all that reply

stuh84

JaCkNiFe wrote: »

I searched the forum for similar topics regarding MST's configuration revision number and came up empty. I have read Cisco's "Understanding Multiple Spanning Tree Protocol (802.1s)", both CCNP:SWITCH books and employed the Google machine finding little information regarding the revision command except the fact that it must match within an MST region. Also, the revision number does not increment unless you were to increment it manually regardless of added or removed configuration.

A typical MST configuration is as follows:

SW1(config)#spanning-tree mst configuration
SW1(config-mst)#name MST_NAME
SW1(config-mst)#revision 1 <----cmd in question (0-65535)
SW1(config-mst)#instance 1 vlan 10, 30
SW1(config-mst)#instance 2 vlan 20, 40
SW1(config-mst)#exit
SW1(config)#spanning-tree mode mst

My question is, "What purpose does the configuration revision number serve?"

Thanks to any and all that reply

The domains in MST are based upon three things, the name, the revision number and vlans, all three have to match for switches to be in the same MST domain.

I'm not entirely sure why they need a revision number on top of the name and VLANs in the domain, but it is what it is.

iproute

It's basically a way for the administrator to "track changes." It should be incremented by 1 after each MST configuration change. It must also match on all switches in the region (as already noted).

yiannit

iproute wrote: »

It's basically a way for the administrator to "track changes." It should be incremented by 1 after each MST configuration change. It must also match on all switches in the region (as already noted).

yeah but its not automatically incremented like VTP

BroadcastStorm

yiannit wrote: »

yeah but its not automatically incremented like VTP

VTP configuration propagates to neighbors MST I believe does not it has to be manually set on switches that will participate, so it's just a tracking mechanism that has to be changed and match by all the switches manually.