%% You should probably cite draft-li-bess-l3vpn-yang instead of this I-D.
@techreport{zhuang-bess-l3vpn-yang-01,
    number =    {draft-zhuang-bess-l3vpn-yang-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-zhuang-bess-l3vpn-yang/01/},
    author =    {Shunwan Zhuang and Zhenbin Li and Xufeng Liu and Vic Liu},
    title =     {{Yang Data Model for BGP/MPLS IP VPNs}},
    pagetotal = 27,
    year =      2015,
    month =     jul,
    day =       6,
    abstract =  {This document defines a YANG data model that can be used to configure and manage L3VPN (BGP/MPLS IP VPN).},
}