[c-nsp] bgp keepalive/hold timers on ethernet links

[matthew zeier]

I'm turing up a new directly connected peer that sits several L2 switches away 
from me (long haul GigE).

me - MM fiber - switch - SM fiber - "something" - SM - switch - MM - peer

As a result, I'll never lose link if the long haul portion goes down and it's 
unlikely that the 100ft MM run will ever fail.

BGP's default 60/180 timers are too long to go before dropping the peer.  The 
PHB wanted 1 second keepalives and a 3 second hold timer.  However, as soon as 
I started pulling in traffic (and only 50Mbps), I began frequently dropping 
the the peer.

Aug 30 17:42:06.016 PDT: %BGP-5-ADJCHANGE: neighbor 216.x.253.233 Up
Aug 30 17:49:40.612 PDT: %BGP-5-ADJCHANGE: neighbor 216.x.253.233 Down BGP 
Notification sent
Aug 30 17:49:40.612 PDT: %BGP-3-NOTIFICATION: sent to neighbor 216.x.253.233 
4/0 (hold time expired) 0 bytes
Aug 30 17:50:21.024 PDT: %BGP-5-ADJCHANGE: neighbor 216.x.253.233 Up
Aug 30 17:57:59.581 PDT: %BGP-5-ADJCHANGE: neighbor 216.x.253.233 Down BGP 
Notification sent
Aug 30 17:57:59.581 PDT: %BGP-3-NOTIFICATION: sent to neighbor 216.x.253.233 
4/0 (hold time expired) 0 bytes

The remote peer also logged the session closed because of:

Last reset 01:07:13, due to BGP Notification sent, hold time expired

While running a continuous ping I verified that the loop was still up while 
bgp was coming down.

I'm guessing that these timers are too aggressive - anyone have any practical 
suggestions on how to fix this?



--
matthew zeier - "But if you only have love for your own race, Then you only
leave space to discriminate, And to discriminate only generates hate." - BEP