The Softwires Working Group is specifying the standardization of discovery, control and encapsulation methods for connecting IPv4 networks across IPv6 networks and IPv6 networks across IPv4 networks in a way that will encourage multiple, inter-operable implementations. For various reasons, native IPv4 and/or IPv6 transport may not be available in all cases, and there is a need to tunnel IPv4 in IPv6 or IPv6 in IPv4 to cross a part of the network which is not IPv4 or IPv6 capable. The Softwire Problem Statement, RFC 4925, identifies two distinct topological scenarios that the WG will provide solutions for, "Hubs and Spokes" and "Mesh." In the former case, hosts or "stub" networks are attached via individual, point-to-point, IPv4 over IPv6 or IPv6 over IPv4 softwires to a centralized Softwire Concentrator. In the latter case (Mesh), network islands of one Address Family (IPv4 or IPv6) are connected over a network of another Address Family via point to multi-point softwires among Address family Border Routers (AFBRs). The focus of this WG is to: Document the softwire encapsulation and control protocol usage for one Address Family (IPv6 or IPv4) over another within the defined problem spaces set out in RFC 4925. Define "Dual-Stack Lite" which uses softwires and IPv4 NAT functions to reduce the amount of Global and RFC 1918 Local IPv4 addressing necessary for a Service Provider with an IPv6-enabled network to continue delivering IPv4 reachability to its customers. The WG will reuse existing technologies as much as possible and only when necessary, create additional protocol building blocks. For generality, all base SOFTWIRE encapsulation mechanisms should support all combinations of IP versions over one other (IPv4 over IPv6, IPv6 over IPv4, IPv4 over IPv4, IPv6 over IPv6). IPv4 to IPv6 translation mechanisms (NAT-PT), new addressing schemes, and block address assignments are out of scope. DHCP options developed in this group will be reviewed jointly with the DHC WG. BGP and other routing and signaling protocols developed in this group will be reviewed jointly with the proper working groups and other workings that may take interest (e.g. IDR, L3VPN, PIM, LDP, SAAG, etc).