Cisco CRS Configuration Manual page 196

Implementing MPLS Layer 3 VPNs
Exchanging VPN Routing Information
• The ASBRs are configured to change the next-hop when sending VPN-IPv4 NLRIs to the iBGP neighbors.
Therefore, the ASBRs must allocate a new label when they forward the NLRI to the iBGP neighbors.
Figure 29: Exchanging Routes and Labels Between MPLS VPN Inter-AS Systems with ASBRs Exchanging VPN-IPv4
Address
The following figure illustrates the exchange of VPN route and label information between autonomous
systems. The only difference is that ASBR2 is configured with the redistribute command with the
connected keyword, which propagates the host routes to all PEs. The command is necessary as ASBR2
is not configured to change the next-hop address.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
182