AS Path

I have removed the weight and local preference so that I show the AS path selection process.

R5#sh route-map

route-map AS_R4, permit, sequence 10

  Match clauses:

  Set clauses:

    as-path prepend 500 500 500 500

  Policy routing matches: 0 packets, 0 bytes

R5#sh run | s router bgp

router bgp 500

 no synchronization

 bgp log-neighbor-changes

 network 5.1.0.0 mask 255.255.255.0

 network 5.2.0.0 mask 255.255.255.0

 network 5.3.0.0 mask 255.255.255.0

 neighbor 150.4.4.4 remote-as 400

 neighbor 150.4.4.4 ebgp-multihop 2

 neighbor 150.4.4.4 update-source Loopback0

 neighbor 150.4.4.4 route-map AS_R4 in

 neighbor 155.1.35.3 remote-as 100

 no auto-summary

Now check the BGP routing table.

R5#sh ip bgp

BGP table version is 53, local router ID is 150.5.5.5

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path

*> 4.1.0.0/24       155.1.35.3                             0 100 400 i

*                             150.4.4.4                0             0 500 500 500 500 400 i

*> 4.2.0.0/24       155.1.35.3                             0 100 400 i

*                             150.4.4.4                0             0 500 500 500 500 400 i

*> 4.3.0.0/24       155.1.35.3                             0 100 400 i

*                             150.4.4.4                0             0 500 500 500

R5 prepending the its own AS path so that now the best route via R3 since it has the shortest route.