%% You should probably cite rfc3931 instead of this I-D.
@techreport{ietf-l2tpext-l2tp-base-15,
    number =    {draft-ietf-l2tpext-l2tp-base-15},
    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-l2tpext-l2tp-base/15/},
    author =    {Mark Townsley and Ignacio Goyret and Jed Lau},
    title =     {{Layer Two Tunneling Protocol - Version 3 (L2TPv3)}},
    pagetotal = 94,
    year =      2004,
    month =     dec,
    day =       2,
    abstract =  {This document describes "version 3" of the Layer Two Tunneling Protocol (L2TPv3). L2TPv3 defines the base control protocol and encapsulation for tunneling multiple Layer 2 connections between two IP nodes. Additional documents detail the specifics for each data link type being emulated. {[}STANDARDS-TRACK{]}},
}