BGP tips

1. Timer
When a connection is started, BGP will negotiate the hold time (only) with the neighbor. The smaller of the two hold times will be chosen. The keepalive timer is then set based on the negotiated hold time/3 and the configured keepalive time, which one is lower.

By default, keepalive is 60 sec and hold time is 180 sec.

R1(Confg)# neighbor R2 timer 10 40
On R1, when you do a show ip bgp R2, it will show keepalive 10 sec and hold time 40 sec.
On R2, when you do a show ip bgp R1, it will show that the keepalive is 13 sec(40/3) and hold time is 40 sec.

R1(Confg)# neighbor R2 timer 80 180
On R1, when you do a show ip bgp R2, it will show keepalive 60 sec(180/3) and hold time 180 sec.