Layer 3 VPN Services over IPv6 Backbone Networks: Requirements, Technology, and Standardization Efforts

Layer 3 virtual private networks (L3VFN) enable organizations to connect geographically dispersed sites to one another across the packet switched network of a service provider. The most popular form of L3VPN is based on BGP/MPLS (border gateway protocol/multiprotocol label switching) technology in which the service provider offers a network-based IP VPN routing and forwarding service to its customers across its own IPv4-based MPLS backbone network. With the deployment of IPv6-based backbone networks underway, there is an emerging requirement to support these same L3VPN services across a native IPv6 backbone network. This introduces a requirement to provide routing and tunneling of IPv6 VPN (and IPv4 VPN) packets across an IPv6 backbone network. Softwires is an Internet Engineering Task Force (IETF) Working Group chartered to address the requirement of providing a generalized, network-based, multi-address family, IP routing and tunneling capability across native IP backbone networks pursuant to IPv6 transitions. Elements of the softwires work can form the basis of an L3VPN over IPv6 solution. After providing a brief overview of how L3VPN works in various topologies, this article presents the requirements for L3VPN services over an IPv6 backbone network and discusses a possible solution set that builds over the softwire technology and related IETF standards. Finally, we outline future directions and how the softwire technology can support new services and improved scalability