[c-nsp] IPv6 neighbor table via SNMP

[Tom Ammon]

Hmmm...After generating some IPv6 traffic, then running the walk, it doesn't seem to know about this OID:

[root at marchingmenfs ~]# snmpwalk -v 2c -c xxxxxxxxxxxxxxxxx inscc-rtr-core-a1-2.redhorn CISCO-IETF-IP-MIB::cInetNetToMediaTable
Cannot find module (CISCO-IETF-IP-MIB): At line 0 in (none)
CISCO-IETF-IP-MIB::cInetNetToMediaTable: Unknown Object Identifier

When I look in the Cisco MIB locator for 12.2(33)SXI6 ( http://tools.cisco.com/ITDIT/MIBS/MainServlet?ReleaseSel=2554&PlatformSel=273&fsSel=35 ) , I don't see a CISCO-IETF-IP-MIB. 

The closest I see is CISCO-IETF-IP-FORWARD-MIB, but trying that one yields the same results:

[root at marchingmenfs ~]# snmpwalk -v 2c -c xxxxxxxxxxxxx inscc-rtr-core-a1-2.redhorn CISCO-IETF-IP-FORWARD-MIB::cInetNetToMediaTable
Cannot find module (CISCO-IETF-IP-FORWARD-MIB): At line 0 in (none)
CISCO-IETF-IPFORWARD-MIB::cInetNetToMediaTable: Unknown Object Identifier


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Phil Mayers
Sent: Saturday, July 09, 2011 4:30 AM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] IPv6 neighbor table via SNMP

On 07/08/2011 06:40 PM, Tom Ammon wrote:
> Hi all,
>
> I'm trying to get the IPv6 ND table via SNMP from my 6506E. When I 
> tried to snmpwalk it, here's what I got:
>
> [root at marchingmenfs ~]# snmpwalk -v2c -c xxxxxxxxxxxxxx 
> inscc-rtr-core-a1-2.redhorn ip.ipNetToPhysicalTable 
> IP-MIB::ipNetToPhysicalTable = No Such Object available on this agent 
> at this OID
>
> [root at marchingmenfs ~]# snmpwalk -v2c -c xxxxxxxxxxxxxx 
> inscc-rtr-core-a1-2.redhorn 1.3.6.1.2.1.4.35 
> IP-MIB::ipNetToPhysicalTable = No Such Object available on this agent 
> at this OID

Try:

CISCO-IETF-IP-MIB::cInetNetToMediaTable

The RFC table isn't in 6500 IOS yet AIUI.

Couple of points:

  1. Just like the IPv4 ARP table, walking this table is sloowwww once you exceed a few thousand entries, as the puny CPU on the sup720 has to numerically sort the OIDs. We use an "expect" script to get the v4/v6 neighbours on our busier routers, as the CLI output comes back in internal/unsorted order, very much faster.

  2. You get "no such oid" if the table is empty, which I find happens a lot if there's virtually no IPv6 traffic! Not such a big problem these days, since Youtube content servers have AAAA record, but make sure there's something in the neighbour table when you're testing.
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