[j-nsp] bgp flap

[Craig Pierantozzi]

The BGP session will close when the hold timer expires. In
JunOS that is 90 seconds, 3 x keepalive.  Set the traceoptions
on the BGP protocols to check to make sure you're sending and
receiving keepalives and to see other events.

user at R1> show configuration protocols bgp traceoptions
    file bgp.log;
    flag packets detail;
    flag general detail;

---snip---

*** bgp.log ***
Feb 16 20:10:37 bgp_send: sending 19 bytes to 10.0.0.4 (Internal AS 65432)
Feb 16 20:10:37 
Feb 16 20:10:37 BGP SEND 10.0.0.1+179 -> 10.0.0.4+4988
Feb 16 20:10:37 BGP SEND message type 4 (KeepAlive) length 19
Feb 16 20:10:39 bgp_read_v4_update: receiving packet(s) from 10.0.0.4 (Internal AS 65432)
Feb 16 20:10:39 
Feb 16 20:10:39 BGP RECV 10.0.0.4+4988 -> 10.0.0.1+179
Feb 16 20:10:39 BGP RECV message type 4 (KeepAlive) length 19
Feb 16 20:10:39 bgp_read_v4_update: done with 10.0.0.4 (Internal AS 65432) received 19 octets 0 updates 0 routes

---snip---

Also check to make sure the router isn't too busy with other
processes.  Maybe something going on that is inhibiting the 
processing of the keepalives?  Other than that more info may
be needed like the config for each side (scrubbed of course), 
state of the session and the network when the session drops, 
how often it drops etc.

regards


* Thus spake Janto Cin (jantocin at datacomm.co.id):

> 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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