FDB info missing on Nexus switches


Was using LibreNMS for some troubleshooting this morning, and it dawned on me that the NXOS switches in the network we’re monitoring weren’t populating the fdb tab

All of the catalyst stuff in the network is fine - but when looking at the global FDB, the nexus devices don’t even appear on the dropdown.

Is this feature supported on NXOS? or am I hitting a problem here?



Component Version
LibreNMS 1.53.1
DB Schema 2019_05_30_225937_device_groups_rewrite (135)
PHP 7.2.19-0ubuntu0.18.04.1
MySQL 10.1.40-MariaDB-0ubuntu0.18.04.1
RRDTool 1.7.0

[OK] Composer Version: 1.8.6
[OK] Dependencies up-to-date.
[OK] Database connection successful
[OK] Database schema correct


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Strangely I have found 2 devices, Nexus 9ks, where there is partial data being displayed -
But on all 5 & 7ks the tables are blank

Cisco does not implement the MIB to expose the FDB table (at least on Nexus5k. I suppose 7k is the same). So there is no way to do it.

Sorry that I create another thread for the same problem, but I just want to tell that I can grab FDB info by the following commands via Snmpwalk.
May FDB table feature on Nexus 5/7K Series is doable with some special mibs?

snmpwalk -v3 -u admin -l authNoPriv -a MD5 -A password ip CISCO-VTP-MIB::vtpVlanState
snmpwalk -v3 -u admin -l authNoPriv -a MD5 -A password ip -n vlan-id BRIDGE-MIB::dot1dTpFdbAddress
snmpwalk -v3 -u admin -l authNoPriv -a MD5 -A password ip -n vlan-id BRIDGE-MIB::dot1dTpFdbPort
snmpwalk -v3 -u admin -l authNoPriv -a MD5 -A password ip -n vlan-id BRIDGE-MIB::dot1dBasePortIfIndex
snmpwalk -v3 -u admin -l authNoPriv -a MD5 -A password ip -n vlan-id IF-MIB::ifName

OIDs listed in order.

I see that you use -n ‘xxxx’ which defines context. This is not supported at all by LibreNMS so far. If you can find a way to access the data without -n, then something is probably doable.

As far as I know, BridgeMIB snmp request in SNMPv3 MUST use context to set VLAN ID. As for SNMPv2, replace -n with @ right after community will be fine.
BTW, why not support context instead.

Contexts are not supported in LibreNMS for the moment, you could open a feature request for them but as it breaks current logic, it will be a huge amount of work to implement them (if ever it is possible). Moreover, contexts are only snmpv3 which means some feature would be bound to snmpv3 only.

So if there is a way to get this data without context, then FDB info could be collected. If not, prerequisite is to handle snmp contexts properly, and then implement FDB.

You got me wrong, it has SNMPv2 equivalences.
I should look into the code and find what’s wrong, maybe we need a set of OID different to IOS.

edit:Find the problem, NXOS was forgotten.

And like magic, after rediscovering my NXOS devices this morning, I seem to have FDB! Thanks very much guys!