[CentOS] One for the Cisco experts...

David.Mackintosh at xdroop.com David.Mackintosh at xdroop.com
Tue Apr 21 18:15:00 UTC 2009


On Tue, Apr 21, 2009 at 11:44:47AM -0500, Sean Carolan wrote:
 
> How can I find out which port on the switch a particular server is
> connected to?  I was hoping that this is somehow possible using the
> mac address and the data gathered from snmpwalk/snmpget requests but
> I'm not having much luck.  How would you tackle this problem?

My notes: http://wiki.xdroop.com/space/snmp/Switching+Tables

Basically there are at least two places in snmp where this might be
stored.  The most obvious is the classic MIB-II Bridge.  The wrinkle
with this MIB is that some switches maintain separate tables for each
VLAN, which means in order to query the switch properly, you have to
query the MIB for each VLAN.

Newer switches populate the Q-Bridge-MIB instead of or as well as the
MIB-II Bridge.  This table contains the VLAN that the target MAC is
reachable through, which is useful since you don't have to know it
ahead of time.

We have a six- or seven- year old cisco 3750 which is running an IOS
which doesn't have the newer MIB; for this switch, we must explicitly
query the MIB-II Bridge for each VLAN.  I would hope that newer
relesaes of IOS wouldn't have this limitation.

-- 
 /\oo/\
/ /()\ \ David Mackintosh | 
         dave at xdroop.com  | http://www.xdroop.com
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