BGP Flapping Issue on Version 12.2(33)****

[pramz087032]

Observed BGP flapping issue on subjected versioned device. In logs i observed -

%BGP_SESSION-5-ADJCHANGE: neighbor 10.72.51.129 IPv4 Unicast topology base removed from session  BGP Notification sent. Is it IOS bug ?

[Ajay Raj]

Hi Pramod,

Can you give continuous ping to the BGP neigbour IP and see if you are getting time outs. If you dont get timeout and still BGP is getting flapped. It could be due to many reasons.

As per my knowledge Verizon uses IPS b/w CE and PE and there is BFD used to support BGP for faster convergence. Since the processing time of IPS is bit slow, when the neighbour doesnt receive any BFD updates, BGP consider it as down, when it receives the packet it considers as UP. Due to this flapping can occur....

Hope this helps...

[sathvik k v]

Hi Pramod,

Is it a P2P or MPLS link  or have you routed over a GRE tunnel? Could you share the configuration.

Regards,

Sathvik

[Vignesh Rajendran Praveen]

Hi Pramod,

Kindly provide the below outputs to assist further.

1) Show log from both peering devices showing the BGP flaps.

2) sh ip bgp summary

3) sh ip bgp neigh x.x.x.x from both devices involved in the peering between which flaps are seen.

Thanks & Regards,

Vignesh R P

[pramz087032]

Hi all,

Thanks for your ack. This is Ebgp(PRI) connection towards ISP. And the logs i have observed was -

%BGP_SESSION-5-ADJCHANGE: neighbor 10.72.51.129 IPv4 Unicast topology base removed from session  BGP Notification sent.