BGP does not perform load balancing. BGP is specifically designed to select the single best route to a destination, therefore it is not able to perform load balancing itself. However, if you can configure BGP over a virtual connection, you can get a Cisco router to balance traffic using up to six static routes.
USING EQUAL COST PATHS
To do so, you set up more than one equal cost path. Using static routes, you can easilly accomplish this. Each static route is configured to reach a matching prefix, and because they are static routes, have equal administrative distance. Most often, static routes are used between two points. BGP is then configured to run over that set of connections using the 'ebgp-multihop' command.
USING LOOPBACK INTERFACES
By setting up connections between two loopback interfaces, the routers can take advantage of the fact that the loopback interface is never down, and will be 'up' so long as it is reachable via the configured static routes.
CONFIGURING BGP 'LOAD BALANCING'
ROUTER A interface serial 0 ip address 184.108.40.206 255.255.255.252 interface serial 1 ip address 220.127.116.11 255.255.255.252 interface loopback 0 ip address 18.104.22.168 255.255.255.255 router bgp 1111 network 22.214.171.124 neighbor 126.96.36.199 version 4 neighbor 188.8.131.52 ebgp-multihop 2 neighbor 184.108.40.206 update-source loopback 0 ip route 220.127.116.11 255.255.255.255 18.104.22.168 ip route 22.214.171.124 255.255.255.255 126.96.36.199 ROUTER B interface serial 0 ip address 188.8.131.52 255.255.255.252 interface serial 1 ip address 184.108.40.206 255.255.255.252 interface loopback 0 ip address 220.127.116.11 255.255.255.255 router bgp 2222 network 18.104.22.168 neighbor 22.214.171.124 version 4 neighbor 126.96.36.199 ebgp-multihop 2 neighbor 188.8.131.52 update-source loopback 0 ip route 184.108.40.206 255.255.255.255 220.127.116.11 ip route 18.104.22.168 255.255.255.255 22.214.171.124