To start BGP on a Cisco router, the following command is required:
router bgp autonomous system number
To define networks to be advertised, apply the following command:
network network-number mask network-mask
You must be aware that the network command is not used in the same way you use it when you apply networks in OSPF or EIGRP. With BGP, you use the network command to advertise networks that originate from the router and need to be advertised through BGP.
To identify peer routers, apply the following command:
neighbor ip-address | peer-group name remote-as autonomous system number