Finding what ports on Cat switch are trunks

Discussion in 'Cisco' started by pzaloum, Feb 27, 2006.

  1. pzaloum

    pzaloum Guest

    I have many Catalyst switches that I am polling with SNMP. I am trying
    to find what ports are acting as trunks.
    On most of the switches it works properly, using
    It returns output like:
    CISCO-VTP-MIB::vlanTrunkPortDynamicStatus.48 = INTEGER: notTrunking(2)
    CISCO-VTP-MIB::vlanTrunkPortDynamicStatus.49 = INTEGER: trunking(1)

    However sometimes it will only return the virtual port doing the
    trunking over other physical ports:

    CISCO-VTP-MIB::vlanTrunkPortDynamicStatus.27 = INTEGER: trunking(1)
    RFC1213-MIB::ifType.27 = INTEGER: propVirtual(53)

    I want to know what PHYSICAL ports are running on the bridge over port

    Does anyone have any ideas to help me out?
    pzaloum, Feb 27, 2006
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  2. I do not remember exact MIB, but there are a series of MIBs, which return
    the interface (or port) description of the SNMP instance. Try to use
    SNMPWALK against that switch, and see what MIB will return the port name for
    the instance .27.

    Good luck,

, Feb 28, 2006
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  3. Do I deduce correct from your VTP reference that the Cat switches
    are running IOS rather than CatOS
    At the moment, this sounds like an application for
    "community string indexing" or it's replacement (which is hard to
    find the documentation for.) Index by the VLAN number and
    probably look at one of the at*Media* series: the port descriptor
    should exist within the indexed community only if the port exists
    within that VLAN.

    There might be an easier way; I do not have ready access to an
    IOS box running VLANs to experiment with.
    Walter Roberson, Feb 28, 2006
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