[j-nsp] bgp flap

[Hyunseog Ryu]

Hi there,

It seems too vague.
I think first step to prevent the problem is to find what cause the problem.
Hold timer expired can be happened when there is keepalive packet 
delivery problem between two peering routers.

If I were you, I will check the interface to see whether there is packet 
drop/CRC/errors or not.
You can use "show interface extensive" to see the detail about Interface 
  counters.
You may check the link utilization, too.
I believe from JUNOS CLI, it is "monitor interface traffic" you can use.
Sometimes because of buffering congestion, and/or bursty data packets, 
the circuit may be used at 100%, so the keepalive packet may be dropped 
to expire hold timer.

If the interface counters and link utilizatin from both peering routers 
are o.k., you may check each router's CPU utilization history.

If receiver's CPU is too busy to handle keepalive packet, it may not 
replied to keepalive packet within allowed period.

I think this gives you brief idea where you can start.

Hyun

It is well-known

Janto Cin wrote:
> 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)
> 
> Many Thanks and Regards,
> Janto
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