6Vpe Network Architecture; Dual Stack - Cisco CRS Configuration Manual

Implementing MPLS Layer 3 VPNs
• Leverages operational IPv4 MPLS backbones.
• Cost savings from operating expenses.
• Addresses the security limitations of 6PE.
• Provides logically-separate routing table entries for VPN member devices.
• Provides support for Inter-AS and CSC scenarios. Inter-AS support for 6VPE requires support of Border

6VPE Network Architecture

The following figure illustrates the 6VPE network architecture and control plane protocols when two IPv6
sites communicate through an MPLSv4 backbone.
Figure 38: 6VPE Network Architecture

Dual Stack

Dual stack is a technique that lets IPv4 and IPv6 coexist on the same interfaces. Coexistence of IPv4 and IPv6
is a requirement for initial deployment. With regard to supporting IPv6 on a MPLS network, two important
aspects of the network should be reviewed:
• Core: The 6VPE technique carries IPv6 in a VPN fashion over a non-IPv6-aware MPLS core, and
• Access: To support native IPv6, the access that connects to IPv4 and IPv6 domains must be IPv6-aware.
Gateway Protocol (BGP) to enable the address families and to allocate and distribute the PE and ASBR
labels.
enables IPv4 or IPv6 communities to communicate with each other over an IPv4 MPLS backbone without
modifying the core infrastructure. By avoiding dual stacking on the core routers, the resources can be
dedicated to their primary function to avoid any complexity on the operational side. The transition and
integration with respect to the current state of networks is also transparent.
Service provider edge elements can exchange routing information with end users; therefore, dual stacking
is a mandatory requirement on the access layer.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
6VPE Network Architecture
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