Internetwork Expert WB VOL 1 - BGP Lab 10

10)BGP Bestpath Selection – Origin

Objective: Modify the BGP Origin code in AS 2 so that traffic from R3’s Ethernet segment going to VLAN 5 is first sent to R1.

Ok, when it comes to ORIGIN ..here is the order of preference IGP-> EGP-> INCOMPLETE. Using this logic I first examined the routing table of R3 and configured it with the below shown configuration.

access-list 1 permit 155.1.5.0 0.0.0.255

route-map NEW_ORIGIN permit 10
set origin egp 1

router bgp 2
neighbor 155.1.0.5 route-map NEW_ORIGIN in
end

Worked like a charm, although over here the WB changes the ORIGIN to ? ie INCOMPLETE!! And also since our objective clearly says that this only needs to be done for traffic going to VLAN 5 from R3, it wouldn’t hurt to match on that specific network prefix using that mentioned access list 1. I just left it out here though, hmm ok next.