MPLS-Transport Protocol (MPLS-TP) is an application of core (G)MPLS technology to next-generation transport networks. It will give service providers an environment similar to their today's SONET/SDH or optical transport networks (OTN) but implemented with MPLS technology. The major differences between MPLS-TP and MPLS are:
- Explicit support for bidirectional paths;
- Support for MPLS-only data plane (without the need to run IP);
- Support for management plane LSP setup (as opposed to control plane LSP setup used in today's MPLS networks).
It is too early in the development cycle of MPLS-TP to allow us to get into technical details, but the broad picture can be extracted from the Requirements of an MPLS Transport Profile (RFC 5654) and the related framework documents.
MPLS-TP is a subset of the MPLS technology. Therefore, it's possible to build parallel IP+MPLS and MPLS-TP networks on the same physical infrastructure, one offering IP and MPLS-based VPN transport and the other one offering traditional circuit-based services. I don't expect to see many providers using this approach. Those that are embracing IP+MPLS wholeheartedly are already offering legacy services across their new MPLS networks.
More conservative service providers might opt to upgrade their existing SONET/SDH/DWDM transport network to MPLS-TP. Those providers will probably retain the separation between tightly-managed transport network (where every action is triggered by the central management software) and the more dynamic IP+MPLS network, which will be just one of many clients of the MPLS-TP network. I suspect that these service providers will be left with a single client of their MPLS-TP network in the long run, as most end-user traffic (including voice) will be migrated to IP anyway … unless, of course, they choose to focus on the fixed-bandwidth-reselling business, where the static nature of MPLS-TP will definitely be beneficial.
This was first published in April 2010