Connecting IPv6 Islands over IPv4 MPLS Using IPv6 Provider Edge Routers (6PE)

This document explains how to interconnect IPv6 islands over a Multiprotocol Label Switching (MPLS)-enabled IPv4 cloud. This approach relies on IPv6 Provider Edge routers (6PE), which are Dual Stack in order to connect to IPv6 islands and to the MPLS core, which is only required to run IPv4 MPLS. The 6PE routers exchange the IPv6 reachability information transparently over the core using the Multiprotocol Border Gateway Protocol (MP-BGP) over IPv4. In doing so, the BGP Next Hop field is used to convey the IPv4 address of the 6PE router so that dynamically established IPv4-signaled MPLS Label Switched Paths (LSPs) can be used without explicit tunnel configuration.