Lab 128 - BGP Remove-Private-AS

Prerequisites: CCNP level skills.

Topology

Pic. 1 - Topology Diagram.

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

Task 1
R5 is connecting to their Service Provider. The company has neither their own public AS number nor their public IP addresses. For the purpose of BGP configuration AS 123 has allocated a private as number for R5 (AS 65005). Configure routers in AS 123 so this private AS number is not advertised over EBGP peerings.

Solution

Task 1
R5 is connecting to their Service Provider. The company has neither their own public AS number nor their public IP addresses. For the purpose of BGP configuration AS 123 has allocated a private as number for R5 (AS 65005). Configure routers in AS 123 so this private AS number is not advertised over EBGP peerings.

Pic. 2 - R4 Receives the Private AS number from R1 and R2.

R1 Configuration:

!

router bgp 123
 no synchronization
 bgp router-id 172.16.101.1
 bgp log-neighbor-changes
 network 172.16.101.0 mask 255.255.255.0
 neighbor 10.1.13.3 remote-as 123
 neighbor 10.1.13.3 next-hop-self
 neighbor 10.1.14.4 remote-as 40
 neighbor 10.1.14.4 remove-private-as
 no auto-summary

!

R2 Configuration:

!

router bgp 123
 no synchronization
 bgp router-id 172.16.102.2
 bgp log-neighbor-changes
 network 172.16.102.0 mask 255.255.255.0
 neighbor 10.1.23.3 remote-as 123
 neighbor 10.1.23.3 next-hop-self
 neighbor 10.1.24.4 remote-as 40
 neighbor 10.1.24.4 remove-private-as
 no auto-summary

!

Pic. 3 - BGP Table on R4.

Notice!
Both R1 and R2 have removed the private AS from their advertisement sent to AS 40.