Carriers cooperate to create global interoperability test bed

CHICAGO'An international consortium of telecom carriers is hosting the second Worldwide Interoperability Demonstration, a 10-week test of intelligent optical networking standards culminating at the SuperComm trade show this week.

The demonstration, organized by the Optical Internetworking Forum, tests support for Ethernet services over multidomain SONET/SDH transport networks in the United States, China and Europe, said Jim Jones, network architect for Alcatel Corp. of Calabasas, Calif.

'Ethernet is proven and mature,' said Jones, who also chairs the OIF technical committee. 'What is lacking is an established wide-area-networking connectivity. The attraction for carriers is the widespread use of Ethernet connections.'

The carrier hosts are providing test facilities, engineering staff and real-world network connections for the demonstration, which began in mid-April. Devices being tested include routers, multiservice provisioning platforms, SONET\SDH cross-connects, optical switches, optical add-drop multiplexers and reconfigurable optical add-drop multiplexers.

Products used in the demonstration employ OIF implementation agreements intended to allow interoperability in a multicarrier, multivendor environment.

Last year's demonstration addressed signaling of SONET/SDH connections from network edge to network edge. Connections were set up on one carrier's network, carried through a second carrier's and terminated on a third network.

This year's event demonstrates client-to-client signaling. This enables Ethernet clients to signal for dynamic connections across the SONET/SDH network without requiring the client to be aware of the underlying server layer network.

The interoperability control plane technologies being demonstrated let switches signal for services across networks. Unlike the traditional centralized connection setup process, intelligence is being distributed to network devices to automate the setup process.

Client-to-client signaling requires network elements on the edge to be able to see the client side Ethernet layer and the SONET/SDH layer in the network.

'It is quite a challenge to perform that edge function and have visibility into both layers,' Jones said.

Testing the implementation agreements for existing standards in a real-world environment is essential, Jones said. The standards are mature. 'What isn't mature is multivendor and multicarrier interoperability.'

Standards do not always reflect real-world conditions and do not by themselves ensure interoperability. Demonstrations provide feedback, helping to identify ambiguities and weaknesses.

'We learned a lot from last year's demonstration in terms of the protocol specifications,' Jones said. Findings from that demonstration suggesting areas of improvement were published last year for standards organizations. 'Some of these enhancements are what we are testing this year.'

The OIF work could help to bring optical networking technology closer to the end user, enabling services such as Ethernet private lines, with dedicated bandwidth between two clients; a virtual Ethernet LAN for shared resources; and virtual trunking for Internet access over shared resources.

The testing moved in stages out of individual labs to create a fully meshed network over which connections can be set up on one carrier's network, carried through a second carrier's and terminated on a third. Test activity is displayed real time by OIF on the SuperComm show floor.

There have been no big surprises so far in this year's demonstration, Jones said. It has shown that although interoperability specifications provide for a variety of options in equipment, not all of the options can be used at the same time. Some delineation is needed for which combinations of services can be used at the same time.

Carriers participating in this year's World Interoperability Demonstration are:
  • AT&T Corp. and Verizon Communications Inc. of New York in the United States

  • Nippon Telegraph & Telephone Corp. in Japan

  • China Telecom

  • Deutsche Telekom, France Telecom and Telecom Italia in Europe.

The carriers that are testing equipment from 13 manufacturers and vendors include:
  • Alcatel

  • Avici Systems Inc. of Billerica, Mass.

  • Ciena Corp. of Linthicum, Md.

  • Cisco Systems Inc.

  • Fujitsu Network Communications Inc. of Richardson, Texas

  • Huawei Technologies, China

  • Lambda OpticalSystems Inc. of Reston, Va.

  • Lucent Technologies Inc. of Murray Hill, N.J.

  • Mahi Networks Inc. of Petaluma, Calif.

  • Marconi Communications Corp. of Warrendale, Penn.

  • Nortel Networks Corp. of Brampton, Ontario

  • Sycamore Networks Inc. of Chelmsford, Mass.

  • Tellabs Operations Inc. of Lisle, Ill.

About the Author

William Jackson is a Maryland-based freelance writer.

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