%% You should probably cite draft-ietf-avt-srtp-not-mandatory instead of this I-D.
@techreport{perkins-avt-srtp-not-mandatory-01,
    number =    {draft-perkins-avt-srtp-not-mandatory-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-perkins-avt-srtp-not-mandatory/01/},
    author =    {Colin Perkins and Magnus Westerlund},
    title =     {{Why RTP Does Not Mandate a Single Security Mechanism}},
    pagetotal = 9,
    year =      2008,
    month =     jul,
    day =       14,
    abstract =  {This memo discusses the problem of securing real-time multimedia sessions, and explains why the Real-time Transport Protocol (RTP) does not mandate a single media security mechanism.},
}