%% You should probably cite rfc5747 instead of this I-D.
@techreport{wu-softwire-4over6-04,
    number =    {draft-wu-softwire-4over6-04},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-wu-softwire-4over6/04/},
    author =    {Jianping Wu and Chris Metz and Xing Li and Mingwei Xu and Yong Cui},
    title =     {{4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions}},
    pagetotal = 15,
    year =      2009,
    month =     dec,
    day =       7,
    abstract =  {The emerging and growing deployment of IPv6 networks will introduce cases where connectivity with IPv4 networks crossing IPv6 transit backbones is desired. This document describes a mechanism for automatic discovery and creation of IPv4-over-IPv6 tunnels via extensions to multiprotocol BGP. It is targeted at connecting islands of IPv4 networks across an IPv6-only backbone without the need for a manually configured overlay of tunnels. The mechanisms described in this document have been implemented, tested, and deployed on the large research IPv6 network in China. This document defines an Experimental Protocol for the Internet community.},
}