Friday Snark – Cisco’s VTP MIB

by gorthx

OK, Cisco, what.is.up. with the CISCO-VTP-MIB? Let’s look at the vtpVersion OID, for starters. One would expect that it would contain, maybe, the vtp version running on the host, right?

Check this out, from the definition for that OID in the mib (available here)

"The version of VTP in use on the local system."
…so it is the VTP version…

"A device will report its version capability and not any particular version in use on the device."

…only not really. (Yes, the documentation contradicts itself. This is one of the reasons network management is so frustrating.)

Turns out you need to read further down in the MIB and use managementDomainVersionInUse (“The current version of the VTP that is in use by the designated management domain.”) to get the VTP version currently running. Right-O.

(The rest of the definition for vtpVersion states: “If the device does not support vtp, the version is none(3).” This wasn’t my experience – most of my switches (3500 and 6500 series) reported ‘none’, and were actually running v1 or v2.)

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