Encapsulating MPLS in IP or GRE
Juniper Networks
Cisco Systems
In various applications of MPLS, label stacks with multiple entries are used. 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 which do not have MPLS enabled in their core routers. This draft specifies two IP-based encapsulations, MPLS-in-IP, and MPLS-in-GRE. Each of these is applicable in some circumstances.