DS-Lite uses NAT44 (also referred to as Carrier Grade NAT, CGN) and IPv4-in-IPv6 (4to6) tunneling to transport IPv4 packets across an IPv6 network to an IPv4 destination. DS-Lite is used to allow all IPv4 traffic that traverses an SP's network after the core of the network is IPv6. The two main components of DS-Lite are the Basic Bridging Broadband (B4) device and the Address Family Transition Router (AFTR)