scope:

This Recommendation describes the functional architecture of Transport MPLS (T-MPLS) bearer plane networks using a subset of the components described in the MPLS layer network architecture of [ITU-T G.8110]. The T-MPLS network functionality is described from a network-level viewpoint, taking into account a T-MPLS network layered structure, client characteristic information, client/server associations, networking topology, and layer network functionality providing T-MPLS signal transmission, multiplexing, supervision, performance and survivability.

This Recommendation describes the bearer plane architecture of T-MPLS networks. Control plane and management plane aspects are outside its scope.

The T-MPLS is a connection-oriented packet-switched transport layer network technology based on the MPLS bearer plane modelled in [ITU-T G.8110]. T-MPLS is a technology focused on packet transport applications that adhere to ITU-T layer network architecture principles. A T-MPLS layer network can operate independently of its clients and its associated control networks (i.e., MCN and SCN). This independence affords network operators the freedom necessary to design robust packet transport networks for their own use and to transport customer traffic. T-MPLS trails can carry a variety of client traffic types. This Recommendation does not specify control or management protocols, but neither does it limit the application of such protocols to T-MPLS transport networks. Finally, transport connections can have very long holding times and thus T-MPLS includes features traditionally associated with transport networks, such as protection switching and operation and maintenance (OAM) functions.

Further, a T-MPLS network will not peer directly with an IP/MPLS network. This means that an LSP initiated from an IP/MPLS network element will be encapsulated before it transits a T-MPLS network. Similarly if IP/MPLS is used as a server layer for T-MPLS then an LSP initiated from a T-MPLS network element will be encapsulated before it transits an IP/MPLS network. This also implies that the control planes for T-MPLS and IP/MPLS are independent.

This Recommendation supports point-to-point Ethernet services as specified in ITU-T G.8011.x-series Recommendations over the T-MPLS layer network.