This document discusses IPv6 transition strategies for service providers. It begins by noting that the IANA pool of IPv4 addresses has been exhausted and regional registries will soon run out as well. While existing IPv4 networks will continue to function, many devices and applications only support IPv4, creating an "IPv4 long tail" that will be challenging to transition to IPv6. The document then evaluates options for service providers, including dual-stack, translators, and tunnels. It provides more detail on implementing a dual-stack infrastructure in the core network using protocols like IS-IS, OSPF, and BGP. 6PE and 6VPE are introduced as options to provide IPv6 connectivity over an IPv4 MPLS