Lab 101 - BGP Path Selection Using Origin

Lab 101 - BGP Path Selection Using Origin
Di Posting Oleh : Simple Learning
Kategori : BGP Core Technologies Routing

Prerequisites: CCNP level skills.

Topology

Personal Note!
This week I'm in Mechelen, Belgium. My poor laptop barely handles four dynamips instances :(.
Pic. 1 - Topology Diagram.
Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
Configure BGP according to the topology diagram (pic. 1). On R1 and R2 advertise 10.1.12.0/24.

Task 2
On R3 use the origin code to prefer R2 towards 10.1.12.0/24.

Lab Solution

Task 1
Configure BGP according to the topology diagram (pic. 1). On R1 and R2 advertise 10.1.12.0/24.

R1 Configuration:
!
router bgp 20
 no synchronization
 bgp router-id 172.16.101.1
 bgp log-neighbor-changes
 network 10.1.12.0 mask 255.255.255.0
 neighbor 10.1.12.2 remote-as 20
 neighbor 10.1.13.3 remote-as 30
 no auto-summary
!

R2 Configuration:
!
router bgp 20
 no synchronization
 bgp router-id 172.16.102.2
 bgp log-neighbor-changes
 network 10.1.12.0 mask 255.255.255.0
 neighbor 10.1.12.1 remote-as 20
 neighbor 10.1.23.3 remote-as 30
 no auto-summary
!

R3 Configuration:
!
router bgp 30
 no synchronization
 bgp router-id 172.16.103.3
 bgp log-neighbor-changes
 neighbor 10.1.13.1 remote-as 20
 neighbor 10.1.23.2 remote-as 20
 no auto-summary
!

Task 2
On R3 use the origin code to prefer R2 towards 10.1.12.0/24.


Pic. 2 - BGP Table on R3.
Notice!
R1 is the gateway towards 10.1.12.0/24 now.

R3 Configuration:
!
ip prefix-list AS20_PREFIX seq 5 permit 10.1.12.0/24
!
route-map SET_ORIGIN permit 10
 match ip address prefix-list AS20_PREFIX
 set origin incomplete
route-map SET_ORIGIN permit 999
!
router bgp 30
 no synchronization
 bgp router-id 172.16.103.3
 bgp log-neighbor-changes
 neighbor 10.1.13.1 remote-as 20
 neighbor 10.1.13.1 route-map SET_ORIGIN in
 neighbor 10.1.23.2 remote-as 20
 no auto-summary
!

Verification:
Pic. 3 - BGP Table on R3.

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