Sample BGP configurations
For Cisco IOS router
The configuration below shows that full routing tables are coming from both IS providers, which requires a considerable memory space. You can reduce the used memory space through reducing the number of routes received from every provider to one route: 0.0.0.0/0 (this has to be discussed with the providers' technical specialists).
ip route <network_address> <netmask> Null0 200
!
router bgp <as_number>
network <network_address> <netmask>
neighbor <provider_A_neighbor_address> remote-as <provider_A_as_number>
neighbor <provider_A_neighbor_address> filter-list 1 out
neighbor <provider_B_neighbor_address> remote-as <provider_B_as_number>
neighbor <provider_B_neighbor_address> filter-list 1 out
!
ip as-path access-list 1 permit ^(<as_number>_)*$ The sample below shows the configuration used with one IS provider only. A full routing table is not accepted; the route is to be manually set by default.
ip route <network_address> <netmask> Null0 200
ip route 0.0.0.0 0.0.0.0 <provider_neighbor_address>
!
router bgp <as_number>
network <network_address> <netmask>
neighbor <provider_neighbor_address> remote-as <provider_as_number>
neighbor <provider_neighbor_address> prefix-list NOD in
neighbor <provider_neighbor_address> filter-list 1 out
!
ip as-path access-list 1 permit ^(<as_number>_)*$
ip prefix-list NOD seq 5 deny 0.0.0.0/0