Softwires (softwires)


Chairs (tentative):

 David Ward <>

 Alain Durand <>


Internet Area Directors:

Mark Townsley

Margaret Wasserman


Internet Area Advisor:

Mark Townsley


Technical Advisors:

Prof Li Tsinghua University

Thomas Narten IBM


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Description of Working Group:


The Softwire Working Group is chartered to specify standardization of discovery, control and encapsulation methods for connecting IPvX networks across IPvY networks in a way that will encourage multiple, inter-operable vendor implementations. Some networks are mandated to be IPv4 or IPv6 only (e.g. due to financial or political reasons); configured tunnels or ‘softwires’ are suited for the inter-networking job. Currently, a number of deployments have been undertaken using the tunnel broker approach, RFC3053. However, as no tunneling encapsulation or configuration protocol is specified in 3053, interoperability and management of the softwires are a significant burden. Other deployments use non-standardized, incomplete solutions.



The focus of this WG is to define a softwire setup negotiation protocol and encapsualtion. This protocol will be able to provide control aspects to negotiate different softwire properties between a customer or network edge node and the corresponding softwire end-point.


Softwire configuration includes two phases: softwire end point discovery and softwire set-up. 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. In the softwire set-up phase, the initator and the ISP negotiate the parameters necessary to establish the softwire. These two phases are orthogonal and independent. The initial milestone for this working group will be the set-up phase. After this is completed, the WG will recharter to focus on the discovery phase and new technological solutions.


Important characteristics of softwires include:


-          IPvX-over-IPvY with possible intermediary encapsulation and be extensible to cover future encapsulation methods of both unicast and multicast traffic.

-          The IP addresses to use for the softwire end-points

-          A control mechanism for softwire setup, policy, autodetection and reconciliation of mismatched parameters (such as MTU, encapsulation, authentication, etc..)

-          Automatic Discovery of softwire endpoints

-          Simple encoding to facilitate implementations in hardware



The WG will reuse existing technologies as much as possible and will create additional building blocks when necessary. The initial selection of potential solutions will come from a bounded set of technologies that are either published as RFCs or in the RFC editor queue.


The WG is chartered to complete the following work items:


1.       Document problem statement and submit to IESG as Informational.


2.       Document softwire encapsulation and control protocol usage for IPvX-over-IPvY with possible intermediary encapsulation 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:



Mar 06    Submit a problem statement to the IESG to be considered

               as an Informational RFC


Nov 06    Submit softwire encapsulation and control protocol to the

                IESG to be considered as a Proposed Standard


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