CENIC has adjusted their BGP timers used on internal sessions and recommends setting these timers on our peering sessions with all members. The timers we use are:
Keepalives: 10 seconds
Hold Time: 30 seconds
This means that it will take between 30 and 40 seconds for a session to drop, giving faster failure detection.
Cisco default values that we are replacing are:
Keepalives: 1 minute
Hold Time: 3 minutes
Which means that by default on Ciscos it can take up to four minutes for the session to fail before BGP can reconverge to backup paths
Juniper default values are:
Keepalives: 30 seconds
Hold Time: 90 seconds
Similarly with the above it can take up to 120 seconds for the session to fail before reconvergence can occur.
The cost of this change is an increased risk of false failure detections, resulting in sessions dropping and routes flapping.