Cisco Cisco IOS Software Release 12.2(33)SRE

In general, ASBRs perform route target replacement at autonomous system borders when the ASBRs 
exchange VPNv4 prefixes. You can also configure the MPLS VPN - Route Target Rewrite feature on 
PE routers and RR routers. 

 shows an example of route target replacement on ASBRs in an MPLS VPN Inter-autonomous 

system topology. This example includes the following configurations:

PE1 is configured to import and export RT 100:1 for VRF VPN1.

PE2 is configured to import and export RT 200:1 for VRF VPN2.

ASBR1 is configured to rewrite all inbound VPNv4 prefixes with RT 200:1 to RT 100:1.

ASBR2 is configured to rewrite all inbound VPNv4 prefixes with RT 100:1 to RT 200:1.

 shows an example of route target replacement on route reflectors in an MPLS VPN 

Inter-autonomous system topology. This example includes the following configurations:

EBGP is configured on the route reflectors.

EBGP and IBGP IPv4 label exchange is configured between all BGP routers.

Peer groups are configured on the routers reflectors.

PE2 is configured to import and export RT 200:1 for VRF VPN2.

PE2 is configured to import and export RT 200:2 for VRF VPN3.

PE1 is configured to import and export RT 100:1 for VRF VPN1.

RR1 is configured to rewrite all inbound VPNv4 prefixes with RT 200:1 or RT 200:2 to RT 100:1.

RR2 is configured to rewrite all inbound prefixes with RT 100:1 to RT 200:1 and RT 200:2.

88324

PE1

PE2

P1

RT Rewrite

200:1 to 100:1

RT Rewrite

100:1 to 200:1

P2

AS 100

AS 200

ASBR1

ASBR2

VPNv4 iBGP

VPNv4 iBGP

VPNv4 eBGP

CE1

VPN1
RT export 100:1
RT import 100:1

VPN2
RT export 200:1
RT import 200:1

CE2