[j-nsp] bgp flap

[Kevin Oberman]

> From: "Janto Cin" <jantocin at datacomm.co.id>
> Date: Thu, 17 Feb 2005 10:37:35 +0700
> Sender: juniper-nsp-bounces at puck.nether.net
> 
> Dear All,
> 
> Need help to know what are the causes for bgp flap with hold timer expired error.
> The link itself didn't flapped.
> How to prevent this?
> 
> Feb 17 01:27:32  GW rpd[2342]: bgp_traffic_timeout: NOTIFICATION sent to 10.1.1.1 (External AS 9999): code 4 (Hold Timer Expired Error), Reason: holdtime expired for 10.1.1.1 (External AS 9999)
> Feb 17 02:41:54  GW rpd[2342]: bgp_read_v4_update: NOTIFICATION received from 10.1.1.1 (External AS 9999): code 4 (Hold Timer Expired Error)
> Feb 17 03:02:00  GW rpd[2342]: bgp_traffic_timeout: NOTIFICATION sent to 10.1.1.1 (External AS 9999): code 4 (Hold Timer Expired Error), Reason: holdtime expired for 10.1.1.1 (External AS 9999)
> Feb 17 03:04:07  GW rpd[2342]: bgp_traffic_timeout: NOTIFICATION sent to 10.1.1.1 (External AS 9999): code 4 (Hold Timer Expired Error), Reason: holdtime expired for 10.1.1.1 (External AS 4761)
> Feb 17 03:49:27  GW rpd[2342]: bgp_read_v4_update: NOTIFICATION received from 10.1.1.1 (External AS 9999): code 4 (Hold Timer Expired Error)

The most common cause of this I have seen is MTU mis-match. A packet is
sent that exceeds the receiver's MTU. It's dropped and re-sent and
dropped again, over and over until the session drops.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634