tracking vlans on switches

Answered Question
May 25th, 2010

I am interested in data to assist troubleshooting when a user  bridges 2 of our VLANs and we subsequently want to know all the possible  locations  this may have occurred.


We run +300 vlans on +700  switches (mostly Cisco).  I want to be able to query a DB with 'what  switches are vlan 5 and vlan 845 on?'.  I have looked at a few MIBs that  will provide data of switch ports by vlan (unfortunately in hex and not  easily adapted to a spreadsheet or DB) but I cannot find a MIB that  might provide a table of switchport and vlan.    


How  do others address this problem?


Thanks

Correct Answer by Joe Clarke about 6 years 9 months ago

There is the vmVlan object from the CISCO-VLAN-MEMBERSHIP-MIB.  For each switchport, this will indicate the access VLAN of the port.  This object will only relibably work for access ports.  For trunk ports, you would need to use the vlanTrunkPortVlansEnabled object from the CISCO-VTP-MIB.  But that would require you to decode the bit string which specifies which VLANs are enabled on the port.


These are the objects that CiscoWorks Campus Manager users to build its VLAN data.

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Correct Answer
Joe Clarke Wed, 05/26/2010 - 21:22

There is the vmVlan object from the CISCO-VLAN-MEMBERSHIP-MIB.  For each switchport, this will indicate the access VLAN of the port.  This object will only relibably work for access ports.  For trunk ports, you would need to use the vlanTrunkPortVlansEnabled object from the CISCO-VTP-MIB.  But that would require you to decode the bit string which specifies which VLANs are enabled on the port.


These are the objects that CiscoWorks Campus Manager users to build its VLAN data.

t8t6p2m054 Thu, 05/27/2010 - 06:58

Joe Clarke, thanks for the object, especially vmVlan, that will be useful.  It doesn't look like a painless solution exists, so I think we'll document this with vmVlan and manually, then monitor for changes with rancid.

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