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As a follow-up to Generate list of subnets on switch using SNMP?, we would like to do the same thing for IPv6 - i.e. poll all of our routers (Juniper and Cisco, at least for now) to identify which IPv6 subnets are active on which interfaces.

For IPv4 it's fairly straightforward to get the ipAdEntAddr and ipAdEntIfIndex, and with the former we can then get the ipAdEntNetMask for each address found. (In our environment we also get the ifAlias; if the combination of these doesn't match what's in our database then we start looking for typos in either the config or the database.)

For IPv6 it's not so obvious how to do get this information; it looks like in the IP-MIB we could query the ipAddressTable, but so far all attempts I've made have returned "IP-MIB::ipAddressTable = No Such Object available on this agent at this OID". On the other hand I've tried a few things using the IPv6-MIB, but from these all I've gotten is "IPv6-MIB::ipv6MIBObjects: Unknown Object Identifier".

I'm clearly missing something; assistance would be appreciated!

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  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin♦ Aug 11 '17 at 3:27
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The answer you were given for IPv4 uses OIDs that existed before RFC4293 and RFC4292. Cisco has updated its MIBs to use protocol-independent objects in the IP-MIB and IP-FORWARD-MIB.

Source: http://www.cisco.com/web/about/security/intelligence/ipv6_mib.html

To cut a long story short, instead of using the node 1.3.6.1.2.1.4.20
try using the node 1.3.6.1.2.1.4.34
and its subnodes.

Cisco's SNMP Object Navigator is useful for visualising the data structure of the MIB.

OID Interface Address

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