6Vpe Operation; How To Implement Mpls Layer 3 Vpns; Configuring The Core Network; Assessing The Needs Of Mpls Vpn Customers - Cisco CRS Configuration Manual

6VPE Operation

6VPE Operation
When IPv6 is enabled on the subinterface that is participating in a VPN, it becomes an IPv6 VPN. The customer
edge-provider edge link is running IPv6 or IPv4 natively. The addition of IPv6 on a provider edge router turns
the provider edge into 6VPE, thereby enabling service providers to support IPv6 over the MPLS network.
Provider edge routers use VRF tables to maintain the segregated reachability and forwarding information of
each IPv6 VPN. MPBGP with its IPv6 extensions distributes the routes from 6VPE to other 6VPEs through
a direct IBGP session or through VPNv6 route reflectors. The next hop of the advertising provider edge router
still remains the IPv4 address (normally it is a loopback interface), but with the addition of IPv6, a value of
::FFFF: is prepended to the IPv4 next hop.
Multiple VRFs on the same physical or logical interface are not supported. Only one VRF, which is used
Note
for both IPv4 and IPv6 address families, is supported.
The technique can be best described as automatic tunneling of the IPv6 packets through the IPv4 backbone.
The MP-BGP relationships remain the same as they are for VPNv4 traffic, with an additional capability of
VPNv6. Where both IPv4 and IPv6 are supported, the same set of MPBGP peering relationships is used.
To summarize, from the control plane perspective, the prefixes are signaled across the backbone in the same
way as regular MPLS and VPN prefix advertisements. The top label represents the IGP information that
remains the same as for IPv4 MPLS. The bottom label represents the VPN information that the packet belongs
to. As described earlier, additionally the MPBGP next hop is updated to make it IPv6-compliant. The forwarding
or data plane function remains the same as it is deployed for the IPv4 MPLS VPN. The packet forwarding of
IPv4 on the current MPLS VPN remains intact.
For detailed information on commands used to configure 6VPE over MPLS, see Cisco IOS XR MPLS
Configuration Guide.

How to Implement MPLS Layer 3 VPNs

This section contains instructions for the following tasks:

Configuring the Core Network

Configuring the core network includes the following tasks:

Assessing the Needs of MPLS VPN Customers

Before configuring an MPLS VPN, the core network topology must be identified so that it can best serve
MPLS VPN customers. Perform this task to identify the core network topology.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
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Implementing MPLS Layer 3 VPNs