Exchange Point Lab Exercise 1
Configuring peering with an Upstream and Configuring Local Peering
We will now set up eBGP between all of the routers in the classroom and an upstream router Each table will be its own AS. For example, Table A is AS 1. Table B is AS 2, etc.
Verify your addressing scheme.
Router(config)#router bgp 1 //use your AS number
Router(config-router)#neighbor 18.104.22.168 remote-as 2
// use the IP address and AS number of your neighbor
Router(config-router)#neighbor 22.214.171.124 description My-Peer-with-AS2
Router(config-router)#neighbor 126.96.36.199 update-source loopback0
Router(config-router)#neighbor 188.8.131.52 prefix-list my-routes out
Router(config-router)#neighbor 184.108.40.206 prefix-list my-peer in
Router(config)#ip prefix-list my-routes seq 5 permit 220.127.116.11/29
Router(config)#ip prefix-list my-routes seq 50 deny 0.0.0.0/0 le 32
Router(config)#ip prefix-list my-peer seq 5 permit 18.104.22.168/29
Router(config)#ip prefix-list my-peer seq 50 deny 0.0.0.0/0 le 32
Notice that you will have to confirm with your neighbor as to what routes they are planning
to send you. In the case above, the neighbor is sending 22.214.171.124/29. Double check
that you set your "my-routes" outbound filter to contain the network you wish to announce.
The entries with sequence number 50 are used to deny default routes.
Router#show ip bgp sum
BGP router identifier 126.96.36.199, local AS number 1
BGP table version is 3, main routing table version 3
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
188.8.131.52 4 2 0 0 0 0 0 never Idle
Router#sh ip bgp neighbor x.x.x.x advertised-routes
Router#show ip bgp
What routes are you receiving?
Other commands to monitor BGP:
Router#sh ip route
Router#sh ip bgp
Router#sh ip bgp neighbor
Router#sh ip bgp neighbor x.x.x.x received-routes [*]
[*] Only works if "soft-reconfiguration inbound" has been configured for this peer
AS number of neighbor Prefixes they will be announcing Ip address for peering
----------------------------- ---------------------------------------- ---------------------------
Often, in a BGP speaker, many neighbors are configured with the same update policies (that is, the same outbound route maps, distribute lists, filter lists, update source, and so on). Neighbors with the same update policies can be grouped into peer groups to simplify configuration and, more importantly, to make updating more efficient. When you have many peers, this approach is highly recommended.
We can use this to simplify our outbound configuration for our peers. We should be announcing just our prefix to our Exchange Point peers:
router bgp 100 neighbor XP-peers peer-group neighbor XP-peers filter-list 99 out neighbor XP-peers neighbor 184.108.40.206 remote-as 200 neighbor 220.127.116.11 peer-group XP-peers neighbor 18.104.22.168 filter-list 400 in neighbor 22.214.171.124 remote-as 300 neighbor 126.96.36.199 peer-group XP-peers neighbor 188.8.131.52 filter-list 401 in neighbor 184.108.40.206 remote-as 400 neighbor 220.127.116.11 peer-group XP-peers neighbor 18.104.22.168 filter-list 402 in
Our Inbound prefix lists will vary for each peer as we will only be accepting only our peersí prefix from each.