Lab 99 - BGP Path Selection using AS-Prepending

Lab 99 - BGP Path Selection using AS-Prepending
Di Posting Oleh : Simple Learning
Kategori : BGP Core Technologies Routing

Prerequisites: CCNP level skills.

Topology

Note!

All routers are configured as per topology diagram (pic. 1) and loopback advertised into BGP.

Pic. 1 - Topology Diagram.

Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
Configure BGP in AS 40, so that R2 prefers path through AS 13 towards 172.16.104.0/24.

Lab Solution


Task 1
Configure BGP in AS 40, so that R2 prefers path through AS 13 towards 172.16.104.0/24.

Pic. 2 - R2's BGP Table.

Notice!

R2 prefers shorter path (through AS 40) to longer one (AS 13 and AS 40)

R4 Configuration:

!

ip prefix-list Lo0 seq 5 permit 172.16.104.0/24

!

route-map PREPEND permit 10
 match ip address prefix-list Lo0
 set as-path prepend 40 40 40
!
route-map PREPEND permit 999
!

router bgp 40
 no synchronization
 bgp router-id 172.16.104.4
 bgp log-neighbor-changes
 network 172.16.104.0 mask 255.255.255.0
 network 172.16.144.0 mask 255.255.255.0
 neighbor 10.1.14.1 remote-as 13
 neighbor 10.1.24.2 remote-as 20
 neighbor 10.1.24.2 route-map PREPEND out
 no auto-summary

!

Verification:

Pic. 3 - R2's BGP Table.

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