Ascend enters optical networking fray

By STEPHEN HARDY

Ascend Communications Inc. (Alameda, CA) threw its weight behind the push to retire the transmission layer from future network topologies with the introduction of an OC-48 (2.5-Gbit/sec) interface that enables its new GX 550 "Smart" Core atm Switch to interface directly into the optical layer. The company is the second data-communications equipment manufacturer to unveil an optical internetworking strategy, a move that reinforces the emerging battle line between traditional telecommunications-equipment providers and upstart data-communications companies for control of tomorrow`s network marketplace.

Ascend`s announcement represents another attack on traditional network architectures that contain separate switching and transmission layers. By incorporating such transmission-layer functions as grooming and automatic protection switching into the GX 550, Ascend contends that carriers and service providers will no longer need Synchronous Optical Network/Synchronous Digital Hierarchy (sonet/sdh) add/drop multiplexers and digital crossconnect systems. The result is a combined switching/transmission layer that is protocol-transparent and provides a simplified, flexible architecture that carriers will find easier to manage.

Like Cisco Systems Inc. (San Jose, CA), its chief competitor in the data-communications arena and the first company from that community to announce an optical internetworking strategy (see Lightwave, June 1998, page 1), Ascend envisions that this new hybrid layer will link directly into the optical layer via wavelength-division multiplexers (wdms) at OC-48 rates. Both companies have OC-192 (10-Gbit/sec) interfaces forthcoming but agree that OC-48 will be the optical internetworking "coin of the realm" for the foreseeable future.

Unlike its data rival, however, Ascend lined up some customers to stand behind its claims that optical internetworking can be implemented today. Both Williams Network (Tulsa, OK) and Frontier Corp. (Rochester, NY) are testing the switch with wdm systems. Wayne Price, network-development manager at Williams, says lab tests of the switch have been conducted already. Interoperability trials with Pirelli`s T-31 omds wdm system have been successfully completed, while similar tests with ciena`s MultiWave Sentry system were due to wrap up in June. Field trials of the GX 550 were slated to follow in July and end this month over a link between Washington and Atlanta. Assuming a successful completion of these trials, Price says Williams will then deploy the switch in its fiber-optic network.

The flexibility provided by atm over optical networks will give Williams a multiservice capability that should prove attractive to the company`s client base of service providers, says Price. The optical internetworking strategy also will significantly simplify network topology while ensuring reliability, he adds.

Interestingly, most of the wdm equipment currently in the Williams network comes from Nortel (Brampton, ON, Canada). But Williams has no plans to conduct interoperability tests with the Nortel equipment, according to Price, who cited a desire to promote a multivendor environment as the reason.

For its part, Frontier will test the interoperability of the GX 550 and the 16-wavelength SpectralWave multiplexer from nec America (Herndon, VA). Jim Watts, Frontier`s director of transmission engineering, says tests originally were planned for June but had been postponed, in all likelihood to July. "It`s just a matter of coordinating with nec and Ascend as to when everybody can get together and get the interfaces out to do that," he says. "Because we certainly have network available to do it."

The network includes two functional sonet rings of more than 3100 mi each in the western United States as well as additional routes across the country. More rings are under construction as part of the company`s ongoing cross-country expansion. The SpectralWave system is an integral part of this infrastructure. Meanwhile, the GX 550 is being deployed as part of an atm network that Frontier also has underway. With both pieces of equipment deployment already, most of the pretest certification work should be completed when the interoperability tests begin. Thus, Watts anticipates the test process will flow smoothly. "I would expect that to get the test up, it wouldn`t take more than a few days to begin testing," he says. Although the test period has yet to be defined, "I think we`ll probably find what we need to find out within two weeks," he predicts.

For the sake of convenience, Watts believes the tests will take place close to Frontier`s Rochester, NY, headquarters. "We`re probably looking at Rochester to Syracuse or Rochester to Buffalo--probably Rochester to Syracuse, because we`ve got an inline amplifier between there," he offers.

A successful test of the OC-48 interface could prove an important step in Frontier`s plans to expand the capabilities of its network. For example, the atm network initially will be set up at OC-12 (622 Mbits/sec); should the interoperability test go well, the higher-speed interface could see deployment starting at the end of this year. Meanwhile, Frontier has further evolution in mind. "We`re going to have a convergence here of IP and atm," Watts reveals. "We`ve got IP over atm, and what we`re looking at is a separate IP network, direct over wdm." The company is investigating IP routers for such an enhancement, he says.

Ascend also has succeeded in spreading the optical internetworking gospel to Europe. Deutsche Telekom Systemloesungen GmbH has selected the GX 550 for use in the Gigabit Testbed operated by Deutsches Forschungsnetz (dfn). The dfn network is a computer-based communications infrastructure for research, science, education, and culture in Germany. The addition of the Ascend hardware will enable the dfn to provide stm-16 (2.5-Gbit/sec)/OC-48 atm core connections for the delivery of video, voice, and data traffic to German universities and research centers.

Meanwhile, more traditional telecommunications transport equipment suppliers have begun to adapt their product lines to meet the carriers` changing needs as well. While it remains too soon to tell whether companies like Cisco and Ascend will carve a significant niche for themselves in the telecommunications market, the willingness of companies like Frontier and Williams to adapt optical internetworking strategies may indicate that new-generation carriers, at least, are willing to listen to what data-equipment manufacturers have to say about the future of optical network architectures. q