SNMP (Agentx) does not show all peers

[patrick7]

The snmpbulkwalk command shows 45 IPv4 BGP sessions:

(ZRH)root@monitor:~# /usr/bin/snmpbulkwalk -v3 -n '' -l 'authPriv' -a 'SHA' -A 'abc' -u 'monitor' -x 'AES' -X 'def' -Oq -m BGP4-MIB -M /var/www/domain.li/subdomains/librenms/mibs:/var/www/domain.li/subdomains/librenms/mibs/supermicro:/var/www/doman.li/subdomains/librenms/mibs/dell udp:cr1.location.domain.li:161 BGP4-MIB::bgpPeerRemoteAs|wc -l
45

But FRR is showing 47:
Total number of neighbors 47

The missing 2 peers:

Neighbor        V         AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd
192.0.2.89     4      34549  119185     105        0    0    0 00:47:42       657583
192.0.2.90     4      34549  120142     105        0    0    0 00:47:44       657582

(the IPs are anonymized)

[patrick7]

If I query for the correct OID, it's there. But snmpwalk does not show it.

[stannous]

Can I see the output of: vtysh -c 'show ip bgp summ' from the router running frr? (as well as the output of snmpwalk on the BGP4-MIB::bgpPeerRemoteAs table. I suspect that these missing peers are in the same AS as the router. (Feel free to send this output to stannous@cumulusnetworks.com).

Sam Tannous
Cumulus Networks

[patrick7]

Hi Sam

Sent per E-Mail.

Best regards
Patrick

[patrick7]

I think I found the root cause.
I start with an empty config:

frr-3# conf t
frr-3(config)# router bgp 65000
frr-3(config-router)# neighbor 192.0.2.89 remote-as 34549
frr-3(config-router)# neighbor 192.0.2.90 remote-as 34549
frr-3(config-router)#
frr-3(config-router)# neighbor PG4-CUSTOMER peer-group
frr-3(config-router)# neighbor 146.48.78.8 remote-as 65517
frr-3(config-router)# neighbor 146.48.78.8 peer-group PG4-CUSTOMER
frr-3(config-router)# end 

While I was inserting the config, a "watch" with snmpbulkwalk was running on the second screen. As soon as I put the peer 146.48.78.8 into the peer group, both AS34549 peers disappeared.

Any ideas?

[stannous]

Hi Patrick,

I think this might be caused by the way the snmp code looks at the bgp peers. The peer group code was added after the snmp code so it's likely the loop over peers needs to be modified. I've opened a ticket to track this internally. Thanks for reporting.
--Sam

[f0o]

Hi,

I have the same issue however only on some peers.
Can it be that neighbors in peergroups with a dash in them are omitted from SNMP?

The only peers that I'm missing are in peer-groups with dashes.
Just my 2cents

I can spin up a test-case later this week to verify this.

[patrick7]

In my test both AS34549 were in no peer group. They have disappeared after I put the AS65517 peer in the group.

[patrick7]

@stannous Are there already some news in the cumulus ticket? :-)

[f0o]

Any news on this? :)

[patrick7]

Any news in the cumulus ticket?

[patrick7]

Any news?

[f0o]

@stannous Any news?

[f0o]

@donaldsharp / @mwinter-osr - Do you guys know if there's any progress on this issue?
It's been open for quite a while and it's rather tedious not to know what peers are doing well which arent via SNMP

[patrick7]

@f0o +1

[f0o]

This is still an issue in FRR 4.0 :(

[patrick7]

@stannous @donaldsharp Any update on this? I think this one is important for a lot of users.