The Internet's leading standards bodies have joined forces to clarify a set of next-generation network transport specifications that critics warned could cause massive interoperability problems for service providers.

The Internet Engineering Task Force (IETF) and the International Telecommunication Union (ITU) formed a joint working group in February to reconsider a special transport network architecture the ITU is developing for MPLS traffic.

Dubbed T-MPLS, the ITU specification would allow MPLS to run over an Ethernet backbone. It would work as an interim layer between Ethernet and MPLS, and carry only MPLS traffic.

The joint working group — the first ever formed by the IETF and ITU — hopes to settle a rare, public spat that developed between the two standards bodies last summer after the IETF charged that T-MPLS was incompatible with the existing MPLS standards.

IETF experts warned the ITU last summer that its T-MPLS specification would not work with the billions of dollars in routers and switches that carriers have installed in recent years based on the IETF's MPLS standards (See Standards vs. Proprietary: One of Networking's 50 Greatest Arguments.)

If left unchanged, T-MPLS would cause "a major train wreck" with MPLS, said Stewart Bryant, IETF liaison to the ITU-T on MPLS issues and a technical leader at Cisco. At an IETF meeting last July, Bryant called the T-MPLS situation "catastrophic."

Now the IETF and ITU are formally teaming up to try to avert this.

"The T-MPLS train is still rolling, and it's yet to be determined whether or not the train wreck is averted. But to keep the analogy going, we've found the train's controls: the gas pedal and the brake pedal. Before, we didn't know where the brakes were," says David Ward, one of the directors of the IETF's routing area who will serve as co-chair of the Ad Hoc Group on T-MPLS. Ward is a Fellow with Cisco.

The ITU's Telecommunication Standardization Sector, known as ITU-T, established the Ad Hoc Group on T-MPLS on Feb. 11 at the plenary meeting of its Study Group 15. The joint working group is the formalization of a plan that the IETF and ITU-T announced last September to try to work together on T-MPLS.

The Ad Hoc Group on T-MPLS consists of around 70 network engineers from leading network equipment vendors including Cisco, Nortel, Alcatel-Lucent, Fujitsu, Huawei, Zte and Ericsson.