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BGP Networks not advertising after an adjacency failure

We have had some BGP adjacency failures and not all network advertisements recover. The neighbor recovers in about 9 seconds but one network does not recover properly. It still shows up in the routing table but we cannot get access to the far end devices until we do a shut, no shut on the internal gig interface. At no time does any of the circuits or links go down. This is a multi-homed environment on two different providers.   

router bgp 65000

bgp log-neighbor-changes

network 10.10.0.0 mask 255.255.0.0

network 10.10.0.254 mask 255.255.255.255

timers bgp 5 15

neighbor 10.12.30.80 remote-as 65001

neighbor 10.12.30.80 description local router

neighbor 10.12.30.80 ebgp-multihop 255

neighbor 10.12.30.80 soft-reconfiguration inbound

neighbor 10.12.30.80 route-map RM--CC out

neighbor 10.10.0.253 remote-as 65000

neighbor 10.10.0.253 update-source Loopback0

neighbor 10.10.0.253 next-hop-self

neighbor 10.10.0.253 soft-reconfiguration inbound

May 30 12:15:42.351 EDT: %BGP-5-ADJCHANGE: neighbor 10.12.30.80 Down BGP Notification sent

May 30 12:15:42.351 EDT: %BGP-3-NOTIFICATION: sent to neighbor 10.12.30.80 4/0 (hold time expired) 0 bytes

May 30 12:15:42.354 EDT: %BGP_SESSION-5-ADJCHANGE: neighbor 10.12.30.80 IPv4 Unicast topology base removed from session  BGP Notification sent

May 30 12:15:51.423 EDT: %BGP-5-ADJCHANGE: neighbor 10.12.30.80 Up

The 10.10.0.0/16 will not recover but the 10.10.0.254 will.

  • WAN Routing and Switching
4 REPLIES
Hall of Fame Super Silver

BGP Networks not advertising after an adjacency failure

Hello Douglas,

10.0.0.254/32 is likely the IP address of the loop0 on the local node.

How is 10.0/16 learned by the node?

there is a static route for IP prefix 10.0/16 pointing to the internal interface?

Is learned by an IGP?

Hope to help

Giuseppe

New Member

BGP Networks not advertising after an adjacency failure

The 10.0.0.254 is the loopback

There is a corresponding 10.0/16 static route pointing back to internal Interface.

Also this has been up and running without issue for a year.

But this same exact incident has happened twice in the last two weeks. No config changes have been made.

Have you ever heard of anything like this?

Re: BGP Networks not advertising after an adjacency failure

When checking the bgp advertized routes, is the missing route listed?

If the other side also has soft reconfiguration enabled, you may try a soft reset.

clear ip bgp 10.12.30.80 soft out

Alternatively, there is this link:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800945ff.shtml

Hope this helps.

regards,

Leo

New Member

Re: BGP Networks not advertising after an adjacency failure

The missing route is listed, but it doesn't work. once we do a shut, no shut, the network entry "restarts" and in the routing table it restarts the time of the route addition. see below

B        10.0.0.0/16 [20/0] via 10.12.30.82, 1d01h

B        10.0.0.253/32 [20/0] via 10.12.30.82, 1d02h

B        10.0.0.254/32 [20/0] via 10.12.30.82, 1d02h

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