BGP hold timer on IX LAN

marcel.duregards at yahoo.fr marcel.duregards at yahoo.fr
Tue Oct 27 07:31:33 UTC 2015


Hello,

As all of us know BGP was designed for scalability, thus slow 
convergence. But it was also when CPU was slow :-).

What do you think about the standard eBGP hold timer of 180sec ? 
Conservative ?

I'm asking because we see more and more peering partners which force the 
hold timer to a lower value, and when BGP negotiate the timer, the 
lowest hold timer is the winner.

Shall we all decide that for global faster convergence we should ALL 
decrease the hold timer ? Or those guys which are lowering their (and 
our) timers on IX LAN play a dangerous game ?


See a example of our peering router at AMS-IX (hold from 30s to 180s):


......
BGP neighbor is 193.239.116.13x,  remote AS 12x54, external link
   Last read 00:00:42, last write 00:00:13, hold time is 180, keepalive 
  interval is 60 seconds

BGP neighbor is 193.239.116.13x,  remote AS 31x77, external link
   Last read 00:00:09, last write 00:00:03, hold time is 90, keepalive 
interval is 30 seconds

BGP neighbor is 193.239.116.13x,  remote AS 4x562, external link
   Last read 00:00:30, last write 00:00:07, hold time is 180, keepalive 
interval is 60 seconds

BGP neighbor is 193.239.116.14x,  remote AS 4x350, external link
   Last read 00:00:01, last write 00:00:01, hold time is 30, keepalive 
interval is 10 seconds

BGP neighbor is 193.239.116.14x,  remote AS 341x1, external link
   Last read 00:00:09, last write 00:00:27, hold time is 180, keepalive 
interval is 60 seconds

BGP neighbor is 193.239.116.14x,  remote AS 2x028, external link
   Last read 00:00:00, last write 00:00:21, hold time is 180, keepalive 
interval is 60 seconds

BGP neighbor is 193.239.116.15x,  remote AS 41x52, external link
   Last read 00:00:27, last write 00:00:11, hold time is 90, keepalive 
interval is 30 seconds

BGP neighbor is 193.239.116.18x,  remote AS 1x041, external link
   Last read 00:00:20, last write 00:00:14, hold time is 90, keepalive 
interval is 30 seconds

BGP neighbor is 193.239.116.18x,  remote AS 162x8, external link
   Last read 00:00:28, last write 00:00:06, hold time is 180, keepalive 
interval is 60 seconds

BGP neighbor is 193.239.116.20x,  remote AS 47x86, external link
   Last read 00:00:59, last write 00:00:21, hold time is 180, keepalive 
interval is 60 seconds

BGP neighbor is 193.239.116.21x,  remote AS x3350, external link
   Last read 00:00:02, last write 00:00:01, hold time is 30, keepalive 
interval is 10 seconds

BGP neighbor is 193.239.116.24x,  remote AS x5133, external link
   Last read 00:00:24, last write 00:00:03, hold time is 90, keepalive 
interval is 30 seconds

.....


I've somehow basically anonymized ip and AS just in case I'm not allowed 
to publish those details.


Best Regards,
-Marcel



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