Softwires (softwire)

Chairs (tentative):

      David Ward <>

     Alain Durand <>

Internet Area Directors:

     Mark Townsley

     Margaret Wasserman

Internet Area Advisor:

     Mark Townsley

Technical Advisors:

     Prof Li Tsinghua University

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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 (financial or political), native IPv4 and/or IPv6 transport may not be available in all cases, and there is need to tunnel IPv4 in IPv6 or IPv6 in IPv4 to cross a part of the network which is not IPv4 or IPv6 capable. Configured tunnels or softwires are suited for the inter-networking job. Non-interoperable tunneling mechanisms have been developed based on the RFC3053 tunnel broker concept, and in addition, standardized mechanisms like RFC2893, RFC2473, GRE, L2TP, etc. have been used in some scenarios. Other deployments use non-standardized, incomplete solutions. The lack of interoperable and/or standardized solution in that space has been noted in the v6ops WG scenario analysis.

The focus of this WG is to define a softwire setup negotiation protocol and encapsulation to be used between a node and the corresponding softwire end-point. Softwire configuration includes two phases: softwire end point discovery and softwire set-up. The WG will attempt to reuse existing technologies as much as possible and if necessary, create additional building blocks. It is expected that existing encapsulations will be the starting point.

In the softwire set-up phase, the initator and the ISP negotiate the parameters necessary to establish the softwire. Those include:

- The encapsulation type: IPv4-over-IPv6 or IPv6-over-IPv4 with a possible intermediary layer (e.g. UDP). This encapsulation negotiation should be extensible to cover future methods of both unicast and multicast traffic.

- How to obtain the IP addresses to use for the softwire end-points. This could be done with an out-of-band mechanism or directly negotiated at set-up phase.

In the softwire end point discovery phase, the initiator gets a name or an IP address for the ISP-side end point of the softwire to establish. This phase is orthogonal to the set-up one.

The initial milestone for this working group will be the set-up phase. This WG is not chartered to work on the discovery phase and a re-charter will be needed prior to undertaking such work; once the base work has been completed (or is well under way), WG may consider re-chartering to address discovery.

The WG will reuse existing technologies as much as possible and will create additional building blocks when necessary.

The WG is chartered to complete the following work items:

1. Document problem statement and submit to IESG as Informational. If this problem statement cannot be written within the IETF process of rough concensus, then the following items will not be advanced.

2. Document softwire encapsulation and control protocol usage for IPv4-over-IPv6 or IPv6-over-IPv4 with possible intermediary layer and submit the specification to the IESG for publication as a Proposed Standard.

3. Develop the softwire MIB module and submit it to the IESG for publication as a Proposed Standard.



Goals and Milestones:

Jan 06 Submit a problem statement to the IESG to be considered as an Informational RFC

Jul 06 Submit softwire encapsulation and control protocol to the IESG to be considered as a Proposed Standard

Oct 06 Submit softwires MIB to the IESG to be considered as Proposed Standard

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