[August 21, 2003]

MPLS/Frame Relay Alliance Approves TDM-over-MPLS Implementation Agreement

The MPLS/Frame Relay Alliance has approved a new Time Division Multiplexing (TDM)-over-MPLS Implementation Agreement (IA). The IA, entitled TDM Transport over MPLS using ATM Adaptation Layer 1 (AAL1), outlines a method for carriers to offer private line TDM services such as n* 64kps (DS0), T1, E1, E3, T3 while delivering new service offerings over a common MPLS network. The new IA may be applied in the design of carrier or Provider Edge (PE) routers, multi-service edge switches and dedicated gateway equipment.

The Alliance is working on numerous work items addressing carrier consolidation of services such as frame relay, ATM, Ethernet, voice, TDM private lines and IP services over a single MPLS infrastructure. The TDM-over-MPLS IA defines the emulation of TDM circuits over MPLS Label Switched Paths (LSPs) by using AAL1 encapsulation. The emulation method defines how the PE will map, encapsulate and tunnel TDM private line traffic over MPLS LSPs. In particular, the IA addresses:

• A suggested method of mapping TDM traffic onto MPLS LSPs
• Definition of protocol data units and procedures for carrying user payloads between nodes
• Exchanging alarm indications between nodes
• MPLS packet loss monitoring procedures

"Service providers today are seeking to increase their profits from existing voice and leased line services by employing a more efficient converged infrastructure," said Andrew G. Malis, Tellabs, chairman and president of the MPLS/Frame Relay Alliance. "TDM-over-MPLS is a technology that enables a variety of leased line services to be offered over MPLS networks, while retaining the reliability and quality of the existing public switched telephone network (PSTN)."

Ron Insler, RAD Data Communications, editor of the MPLS/Frame Relay Alliance TDM over MPLS using ATM AAL1 IA, said, "For vendors this IA enables re-use of designs based on well-known AAL1 mechanisms, hence speeding time-to-market, while for operators, this approach is an evolutionary application of mature protocols, minimizing learning time and facilitating interworking with standard ATM-based circuit emulation systems."

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