This is an example of how to configure BGP neighbor between two routers (suppose all interfaces are configured correctly)
|R1(config)#router bgp 1
R1(config-router)#neighbor 126.96.36.199 remote-as 2
|R2(config)#router bgp 2
R2(config-router)#neighbor 188.8.131.52 remote-as 1
So as you see, we need the neighbor’s IP address and neighbor’s AS number for the BGP neighbor relationship.