On Sat, May 23, 2020 at 12:47:58AM +0300, Esa Kuusisto wrote:
> Hi
> 
> I upgraded today two openbsd routers with openbgpd from 6.6 -> 6.7. Upgrade
> was done using sysupgrade. Router1 and Router2 have two ebgp peers, two
> iBGP peers to local switches and one iBGP peer between Router1 <->Router2.
> Router2  was first upgraded and no problems there. After Router1 upgrade I
> saw high cpu utilization from bgpd. From logs I saw that both Router1 and
> Router2 saw two networks being updated between each other and withdraw
> multiple times every second:
> 
> May 23 00:20:24 Router1 bgpd[22905]: Rib Loc-RIB: neighbor AAA.BBB.211.252
> (PeerRouter2_v4) AS43XXX: withdraw 149.63.0.0/17
> May 23 00:20:24 Router1 bgpd[22905]: Rib Loc-RIB: neighbor AAA.BBB.211.252
> (PeerRouter2_v4) AS43XXX: withdraw 149.63.59.0/24
> May 23 00:20:24 Router1 bgpd[22905]: Rib Loc-RIB: neighbor AAA.BBB.211.252
> (PeerRouter2_v4) AS43XXX: update 149.63.0.0/17 via AAA.BBB.211.252
> May 23 00:20:24 Router1 bgpd[22905]: Rib Loc-RIB: neighbor AAA.BBB.211.252
> (PeerRouter2_v4) AS43XXX: update 149.63.59.0/24 via AAA.BBB.211.252
> 
> May 23 00:17:44 Router2 bgpd[17698]: Rib Loc-RIB: neighbor AAA.BBB.211.253
> (PeerRouter1_v4) AS43XXX: withdraw 149.63.0.0/17
> May 23 00:17:44 Router2 bgpd[17698]: Rib Loc-RIB: neighbor AAA.BBB.211.253
> (PeerRouter1_v4) AS43XXX: withdraw 149.63.59.0/24
> May 23 00:17:44 Router2 bgpd[17698]: Rib Loc-RIB: neighbor AAA.BBB.211.253
> (PeerRouter1_v4) AS43XXX: update 149.63.0.0/17 via AAA.BBB.211.253
> May 23 00:17:44 Router2 bgpd[17698]: Rib Loc-RIB: neighbor AAA.BBB.211.253
> (PeerRouter1_v4) AS43XXX: update 149.63.59.0/24 via AAA.BBB.211.253
> 
> Router1
> Neighbor                   AS    MsgRcvd    MsgSent  OutQ Up/Down
>  State/PrfRcvd
> PeerRouter2_v4          43XXX    5564646    5639942     0 00:47:19 810647
> PeerRouter2_v6          43XXX      52294      82663     0 00:47:19  85391
> 
> Router2
> Neighbor                   AS    MsgRcvd    MsgSent  OutQ Up/Down
>  State/PrfRcvd
> PeerRouter1_v4          43XXX    6039364    6037168     0 00:47:34 810654
> PeerRouter1_v6          43XXX     421226     417520     0 00:47:34  87247
> 
> I do not have any relation to those 149.63/17 and 149.63.59/24 networks.
> 
> For debug purposes I did filter those announcements and problem was fixed.
> I did remove filter to test if the announcement loop was gone and it was
> for now.
> No configuration changes to bgpd.conf before or after upgrade (except that
> filter after the high cpu load reason was found).
> 
> Br
> -Esa Kuusisto
> 

Please provide the bgpd.conf files for both routers. There are many ways
you can create an update loop and it is impossible to tell you what it is
without knowing the exact config.

-- 
:wq Claudio

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