2.3.17 Softwires (softwire)

NOTE: This charter is a snapshot of the 77th IETF Meeting in Anaheim, California USA. It may now be out-of-date.

Last Modified: 2009-04-13


David Ward <dward@juniper.net>
Alain Durand <adurand76@comcast.net>

Internet Area Director(s):

Ralph Droms <rdroms.ietf@gmail.com>
Jari Arkko <jari.arkko@piuha.net>

Internet Area Advisor:

Ralph Droms <rdroms.ietf@gmail.com>

Technical Advisor(s):

Xing Li <xing@cernet.edu.cn>

Mailing Lists:

General Discussion: softwires@ietf.org
To Subscribe: softwires-request@ietf.org
In Body: With a subject line: subscribe
Archive: http://www.ietf.org/mail-archive/web/softwires/current/maillist.html

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 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).

Goals and Milestones:

Done  Submit a problem statement to the IESG to be considered as an Informational RFC
Nov 2008  Submit Mesh softwire encapsulation and control protocol to the IESG to be considered as a Proposed Standard
Nov 2008  Submit H&S softwire encapsulation and control protocol to the IESG to be considered as a Proposed Standard
Mar 2009  Submit dual-stack lite to the IESG to be considered as a Proposed Standard. The initial basis for this solution is described in draft-durand-dual-stack-lite-00.txt and draft-droms-softwires-snat-01.txt.
Dec 2009  Submit softwires MIB to the IESG to be considered as Proposed Standard


  • draft-ietf-softwire-dual-stack-lite-04.txt
  • draft-ietf-softwire-ipv6-6rd-10.txt
  • draft-ietf-softwire-ds-lite-tunnel-option-02.txt
  • draft-ietf-softwire-gateway-init-ds-lite-00.txt

    Request For Comments:

    RFC4925 I Softwire Problem Statement
    RFC5512 PS The BGP Encapsulation Subsequent Address Family Identifier (SAFI) and the BGP Tunnel Encapsulation Attribute
    RFC5543 PS BGP Traffic Engineering Attribute
    RFC5549 PS Advertising IPv4 Network Layer Reachability Information with an IPv6 Next Hop
    RFC5565 PS Softwire Mesh Framework
    RFC5566 PS BGP IPsec Tunnel Encapsulation Attribute
    RFC5571 PS Softwire Hub and Spoke Deployment Framework with Layer Two Tunneling Protocol Version 2(L2TPv2)
    RFC5619 PS Softwire Security Analysis and Requirements
    RFC5640 PS Load Balancing for Mesh Softwires

    Meeting Minutes


    Chair slides