%% You should probably cite draft-ietf-trill-rbridge-multilevel instead of this I-D.
@techreport{perlman-trill-rbridge-multilevel-05,
    number =    {draft-perlman-trill-rbridge-multilevel-05},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-perlman-trill-rbridge-multilevel/05/},
    author =    {Radia Perlman and Donald E. Eastlake 3rd and Anoop Ghanwani and Hongjun Zhai},
    title =     {{Alternatives for Multilevel TRILL (Transparent Interconnection of Lots of Links)}},
    pagetotal = 24,
    year =      2012,
    month =     dec,
    day =       5,
    abstract =  {This is an informational document describing issues and comparing general advantages and disadvantages of various approaches to extending TRILL (Transparent Interconnection of Lot of Links) to use multilevel IS-IS (Intermediate System to Intermediate System) routing to improve TRILL's scalability.},
}