BGP_Router: unhandled major event code 128, minor 0

[ChuckMcF]

We're running SDA. Our External Border Nodes are iBGP neighbors and each have an uplink to the two Fusion Routers (eBGP). I logged into each of the EBNs, turned on term mon, and then typed debug bgp ipv4 uni <neighbor IP>. Instantly the screen was filled with the following:

2d21h: BGP_Router: unhandled major event code 128, minor 0
2d21h: BGP_Router: unhandled major event code 128, minor 0
2d21h: BGP_Router: unhandled major event code 128, minor 0
2d21h: BGP_Router: unhandled major event code 128, minor 0
2d21h: BGP_Router: unhandled major event code 128, minor 0

Have any of you ever seen this? We're not really seeing any issues, I was just taking a deep dive into the device(s) during a rare calm moment in our office when I ran into this. Appreciate any thoughts.

EBNs and fusion routers are 9500-16X-A running IOS XE 16.9.2.

Chuck

[Giuseppe Larosa · Accepted solution]

Hello Chuck,

you say that you have no real issues in your network so I assume your eBGP sessions are fine.

According to the following document last post the message may be originated when a new prefix is learned:

https://learningnetwork.cisco.com/thread/84357

If so, nothing to worry about it.

In other documents it is mentioned the case of a mismatch between configured AS number for the eBGP peer and the actually received BGP AS number in the BGP initial messages.

Of course in this case the eBGP session cannot reach the established state. But this shouldn't be your case as you have written there are no real issues in your network.

Hope to help

Giuseppe

[ChuckMcF]

Giuseppe,

Thank you for your fast response. Correct, everything seems to be fine and we're peering to the eBGP neighbors without issue. I have a ticket open with TAC as well. If I find out any additional information I will pass it along in this thread.

Chuck

[crescentwire · Accepted solution]

Hi Chuck,

Did you ever reach any conclusion with TAC on this? We're seeing this exact behavior between eBGP peers, though it coincides with a route's lifetime reaching 30 seconds and then being reset to 0:

R2#sh ip route | i 0.0.0.0
Gateway of last resort is x.x.x.x to network 0.0.0.0
B*    0.0.0.0/0 [20/0] via x.x.x.x, 00:00:29
      10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
R2#sh ip route | i 0.0.0.0
Gateway of last resort is x.x.x.x to network 0.0.0.0
B*    0.0.0.0/0 [20/0] via x.x.x.x, 00:00:00
      10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
R2#
000645: Nov 26 06:51:40.020 EST: BGP_Router: unhandled major event code 128, minor 0

I plan to engage TAC but wondered if you had any updates from them with your open case.

[ChuckMcF]

Please forgive the slow response. I was just looking through old posts and realized I never responded to your question - my apologies.

I never did reach a resolution with TAC. We upgraded IOS XE on all of our devices due to a published CVE. Once we upgraded the issue went away. We closed the ticket with TAC under the assumption that this was a bug in the code.

[ChuckMcF]

UPDATE: This issue has been resolved after upgrading to 16.12.1s. 

Chuck