[Xorp-users] Route Redistribution issue in BGP - Kindly help asap.

Santhosh Sundararaman santhosh at ku.edu
Thu Oct 26 00:29:04 PDT 2006


Hi,
I have a BGP router that is peered to one E-BGP  peer and one I-BGP 
peer. There are several routers in the local AS and OSPF is the IGP. I 
am trying to redistribute the OSPF routes into BGP such that the OSPF 
routes are advertised to the EBGP peer but not the IBGP peer.  The 
following is the configuration I am using.

protocols {
    bgp {
        bgp-id: 172.16.10.3
        local-as: 65001

        export: "routes_as1_to_as2"

        peer 172.16.10.1 { /* EBGP Peer*/
            local-ip: 172.16.10.3
            as: 65002
            next-hop: 172.16.10.3
            holdtime: 120
            ipv4-unicast: true
        }
       
        peer 10.5.11.1 { /*IBGP Peer*/
            local-ip: 10.10.11.2
            as: 65001
            next-hop: 10.10.11.2
            holdtime: 120
            ipv4-unicast: true
        }
    }   
}

policy {
    policy-statement "routes_as1_to_as2" {
        term "ospf_routes" {
            from {
                    protocol: "ospf4"
            }
            to {
                neighbor: 172.16.10.1
            }
            then {
                accept /*adv ospf routes to EBGP Peer*/
            }
        }

        term "reject_ospf4_to_ibgp_peer" {
            from {
                    protocol: "ospf4"
            }
            to {
                    neighbor: 10.5.11.1
            }
            then {
                    reject /*Rej ospf routes to IBGP Peer*/
            }
        }
    }
}

On using this policy the routes get advertised to both EBGP and IBGP 
peers and "reject_ospf_to_ibgp_peer" term appears to be ignored. I have 
tried specifying "reject_ospf_to_ibgp_peer" without any 
to{neighbor:10.5.11.1}  rule, in which case the routes were not 
advertised to any of the peers. Am I missing something??

The address matched against the neighbor variable in the to {} rules, is 
the address of the interface of the peer to which peering is establish 
and not the bgp-id of the peer, is that correct or should it have been 
the peers bgp-id instead.

Also inside the bgp protocol construct when specifying the peers, should 
the peer address be the bgp-id of the peer, or can it be any one of the 
several interface addresses of the peer which may not be the bgp-id.

Any help would be greatly appreciated.

Thanks
Santhosh



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