@misc{rfc4023,
    series =    {Request for Comments},
    number =    4023,
    howpublished =  {RFC 4023},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC4023},
    url =       {https://www.rfc-editor.org/info/rfc4023},
    author =    {Eric C. Rosen and Tom Worster and Yakov Rekhter},
    title =     {{Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)}},
    pagetotal = 14,
    year =      2005,
    month =     mar,
    abstract =  {Various applications of MPLS make use of label stacks with multiple entries. In some cases, it is possible to replace the top label of the stack with an IP-based encapsulation, thereby enabling the application to run over networks that do not have MPLS enabled in their core routers. This document specifies two IP-based encapsulations: MPLS-in-IP and MPLS-in-GRE (Generic Routing Encapsulation). Each of these is applicable in some circumstances. {[}STANDARDS-TRACK{]}},
}