The ITU-T argued that this situation is fine because MPLS and T-MPLS will be used on networks that don't connect to each other. The IETF says it is unrealistic to assume that MPLS and T-MPLS traffic will never co-exist on the Internet.

"T-MPLS was originally floated as something that would be used completely disjoint from MPLS. But it gradually became more and more obvious that it was not quite as disjoint as its original proponents suggested," Betts says. "It's really thanks to the IETF intervention that we were able to halt T-MPLS and get things back on the proper stable footing."

The Ad Hoc Group on T-MPLS will consider the following aspects of T-MPLS and MPLS:

• forwarding plane
• operations, administration and maintenance
• control plane
• network survivability
• transport equipment and network management

Betts says that if the Ad Hoc Group on T-MPLS goes according to plan, the IETF and ITU-T may form similar joint working groups in the future.

"One of the things we need to give to the ITU in the May timeframe is a readout on how the process is working," Betts says. "There are a number of areas where the IETF and the ITU-T need to cooperate in the future, and these are some pretty big, significant things. We need to make sure we have the right model to work together."

Ward says the issue of how the IETF and ITU can work together in the future is "incredibly significant. The ITU as a standards body is engaging more and more in defining IP and MPLS technology. We're seeing T-MPLS as not only a technical issue but an experiment in how the two standards bodies can work together."