CHICAGO - The lack of a standard Ethernet interface between different carrier networks is impeding carrier plans to extend virtual private LAN services on a national and global scale.

Carriers at last week's Supercomm 2005 conference here say they require a standard network-to-network interface (NNI) between their own and other carrier networks to offer consistent multipoint Ethernet services for customers with operations across the country or the world. They say such a virtual private LAN service (VPLS) NNI would let them offer consistent service quality and more reliable service-level agreement (SLA) guarantees for meshed intercarrier Ethernet connectivity extending beyond the metropolitan-area boundary.

"We want to be able to map services" across carrier boundaries, says Michael Rouleau, senior vice president of business development and strategy at Time Warner Telecom. "The last thing we want is lowest common denominator" service.

"VPLS will be very important for maintaining QoS through a multivendor infrastructure," says Craig Drinkhall, senior vice president of product development and engineering at TelCove, a competitive local exchange carrier in Pittsburgh. "But not all of the standards are put together to create vendor interoperability."

However, others argue that even with a standard NNI, carriers will have to enter into lengthy negotiations and testing with specific peers to extend SLA guarantees across carrier boundaries.

The Metro Ethernet Forum (MEF) is working on an Ethernet NNI (ENNI) that would describe how carriers can pass off services between their networks. This specification could be ready next year, MEF officials say.

Work on the ENNI started three years ago but has been idle for about a year because key people working on it were reassigned at their companies and could not commit enough time to it, says Bill Bjorkman, an enterprise marketing consultant for Verizon and co-chairman of the MEF technical committee. But AT&T, Verizon and Cisco are interested in resurrecting the work and have scheduled teleconferences over the next few months to try to wrap it up, he says.

But without ENNI, Broadwing and other carriers have to hammer out individual and specific peering relationships with other carriers in order to extend VPLS-based Layer 2 Ethernet VPN service guarantees. Indeed, at the Supercomm conference, Broadwing announced a relationship with metropolitan service provider OnFiber to pair Broadwing's nationwide Layer 2/3 Converged Services offering with OnFiber's Ethernet local access network to deliver end-to-end VPLS- and MPLS-based VPNs.