R1

show ip bgp summary
show ip bgp 

debug ip bgp 12.12.12.2 updates
debug ip bgp events


conf t
router bgp 2
neighbor 12.12.12.2 remote-as 1


show ip bgp summary
show ip bgp 



R2

show ip bgp summary
show ip bgp 


conf t
router bgp 1
neighbor 12.12.12.1 remote-as 2



show ip bgp summary
show ip bgp