SNMP MSTP Management using CISCO-STP-EXTENSIONS-MIB

Unanswered Question
Jun 13th, 2007

Hi, I have enabled the SNMP agent on a Cat 3560G and have downloaded and parsed various Cisco mibs, including the CISCO-STP-EXTENSIONS-MIB.my mib, in to our MIB browser. This has enabled me to successfully set the bridge spanning-tree mode to mst and configure the mst name and revision level using SNMP. However, I cannot locate the mib object to set or get the instance priority or the port costs and port priorities for each instance. I can successfully set these via CLI. Does anybody know if these objects exist in a different MIB? I have searched many mibs but have been unable to locate them.

Many thanks in advance.

Tony

I have this problem too.
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Joe Clarke Wed, 06/13/2007 - 07:40

These values are typically set using BRIDGE-MIB objects, however, I have not tested this with MST. You will need to use community string indexing at the very least to do this on a per-instance basis. Your indexes will be mst-X where X is the instance number. For example, "[email protected]-2" would be a community string to set objects in MST instance 2.

Then try setting dot1dStpPortPriority or dot1dStpPortPathCost for the port ID you want using that community string.

Or set dot1dStpPriority.0 using that community string.

tonydoy69 Thu, 06/14/2007 - 07:04

Many thanks for this - you are right. I performed 'snmp-server community [email protected]-x rw' where x is an incremental number representing the instance.

Instance Priority: With the above it is now possible to read the instance priority from BRIDGE-MIB::dot1dstpPriority.0 by quoting the appropriate community string for the instance i.e. 'snmpget -c [email protected]-1 -v 2c dot1dstpPriority.0' for instance 1. I have noticed however, that the value returned is actually the priority plus the instance number i.e. 4097 for instance 1 which has been set to 4096.

Port Priority: This works as expected with the correct community string getting and setting 'BRIDGE-MIB::dot1dstpPortPriority.'.

Port Cost: I have been having problems with this one. I can get the cost by performing 'snmpget -c [email protected]-1 -v 2c dot1dstpPortPathCost.', this returns an integer value e.g. 1000. However, I have been unable to set this object. I have been getting the error message "inconsistentValue (The set is illegal or unsupported in some way)". This is after performing 'snmpset -c [email protected]-1 -v 2c dot1dstpPortPathCost. i 1000'. Is there a peculiar way of setting the port path cost?

Regards

Tony

Joe Clarke Thu, 06/14/2007 - 07:27

What version of code is this switch running? It may not be possible to set all of these objects.

tonydoy69 Fri, 06/15/2007 - 05:34

The software running is Version 12.2(25r)SE1, Release Software (fc).

I have noticed that it is possible to get the port state from dot1dStpPortState but there is no equivalent for port Role - which is available via CLI.

Joe Clarke Fri, 06/15/2007 - 07:39

That version appears to be the boot loader version. Please include the entire show ver.

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