Softwires (softwire)

Description of Working Group

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 Softwires Problem Statement, RFC 4925, identifies
two distinct topological scenarios that the Working Group will
provide solutions for: "Hubs and Spokes" and "Mesh." In the former
case (Hubs and Spokes), 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 Softwires Working Group will reuse existing technologies as much
as possible and only when necessary, create additional protocol
building blocks.

For generality, all base softwires 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/IPv6
translation mechanisms, new addressing schemes, and block address
assignments are out of scope. DHCP options developed in this working
group will be reviewed jointly with the DHC Working Group. RADIUS
attributes developed in the Softwires Working Group will be reviewed
jointly with the RADEXT Working Group. The MIB Doctors directorate
will be asked to review any MIB modules developed in the Softwires
Working Group. 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).

The specific work areas for this working group are:

1. Developments for Mesh softwires topology; the Mesh topology work
will be reviewed in the L3VPN and IDR Working Groups
- multicast
- MIB module

2. Developments for 6rd:
- multicast
- operational specification
- RADIUS attribute for 6rd server
- MIB module
- Gateway-initiated 6rd (GI-6rd)

3. Developments for Dual-Stack Lite (DS-Lite):
- multicast
- operational specification
- RADIUS attribute for AFTR
- proxy extensions; GI-DS-Lite; No NAT on AFTR
- MIB module

4. Developments for stateless legacy IPv4 carried over IPv6
- develop a solution motivation document to be published as an
RFC
- develop a protocol specification response to the solution
motivation document; this work item will not be taken through
Working Group last call until the solution motivation document
has been published or approved for publication

5. Finalize discovery and configuration mechanisms for a gateway to
use DS-Lite or 6rd; these discovery and configuration mechanisms
must take into a account other operating environments such as
dual-stack and tunneling mechanisms not defined by the Softwires
Working Group. Development of new mechanisms will involve the
DHC and/or V6OPS Working Groups as appropriate

Other work items would require Working Group approval and rechartering.

Goals and Milestones