[c-nsp] Problem using SNMPget for ipAdEntIfIndex and IfIndex (7600, 3660, 7200)

[Phil Mayers]

On Fri, 2007-07-27 at 10:08 +0000, Anton Smith wrote:
> Hi all, the following is on behalf of a work mate:

Sadly the ipAdEnt* table is one of the less well-designed MIBs (e.g.
ipNetToMedia has ifIndex *before* the IP so can handle VRFs and
overlapping IP space just fine without modification)

There's a bunch of documentation on the Cisco site about binding snmpv3
contexts to a VRF and getting VRF-specific MIBs, but it's never worked
when I tried it. Google for:

site:cisco.com snmp context vrf

Also see the MPLS-VPN mib - you could look under mplsVpnVrfRouteProto
for "local" routes, then extract the route and output ifIndex.

> 
> ------------
> 
> Problem using SNMPget for ipAdEntIfIndex and IfIndex on Cisco 
> 7600/3660/7200:
> 
> It regards getting information on what ipaddress is connected to what 
> interface.
> I use ipAdEntIfIndex to find out what ipaddress goes with what ifIndex.
> Example: IP-MIB::ipAdEntIfIndex.10.10.10.10 = INTEGER: 111
> Here I've connectect an interface to a VRF called for example A, and 
> configure the ipaddress 10.10.10.10 with whatever mask.
> This ipaddress in configured on an  interface I call Loopback660.
> 
> Now if I create another interface called Loopback661 and connect it to 
> another VRF B, but with the same IP address 10.10.10.10, the oid changes 
> to: IP-MIB::ipAdEntIfIndex.10.10.10.10 = INTEGER: 112
> And the other oid disappears. So it’s overwritten.
> Now I have two interfaces on different VRF’s with the same IPaddress.
> 
> The configuration works fine of course, but when I try to manage my 
> IPaddress list through SNMP I have problems distinguishing between two 
> interfaces.
> 
> What I'm trying to do is to input the ipaddress 10.10.10.10 and find out 
> what interface it is connected to.
> 
> 
> Any information on what I could do to fix this?
> 
> --------------
> 
> Regards,
> Anton
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