%% You should probably cite rfc4093 instead of this I-D.
@techreport{ietf-mip4-vpn-problem-statement-03,
    number =    {draft-ietf-mip4-vpn-problem-statement-03},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-mip4-vpn-problem-statement/03/},
    author =    {Farid Adrangi and Henrik Levkowetz},
    title =     {{Problem Statement: Mobile IPv4 Traversal of Virtual Private Network (VPN) Gateways}},
    pagetotal = 19,
    year =      2004,
    month =     oct,
    day =       6,
    abstract =  {Deploying Mobile-IP v4 in networks that are connected to the Internet through a Virtual Private Network (VPN) gateway presents some problems that do not currently have well-described solutions. This document aims to describe and illustrate these problems, and to propose some guidelines for possible solutions. This memo provides information for the Internet community.},
}