Next-Generation Routers Join Next-Wave Optic Technology


The introduction of next-generation routers has suddenly become linked with next-generation optical technology, where major vendors are seeking to combine the switching of Internet-protocol traffic at terabit speeds with the ability to switch wavelengths without converting them to electronic signals.

Lucent Technologies, which just moved its terabit router into commercial production, is one of the leading forces on this front, thanks to the success of its Bell Labs group in developing a practical micro-mirror technique for use in all-optical cross-connects.

Nortel Networks is another, having moved to acquire a developer of similar optical technology to advance its own broadband IP-systems strategy.

The new Lucent router-developed by Nexabit Networks, a firm it acquired last year-supports up to 6.4 terabits per second in switching capacity per chassis. This allows carriers to operate at OC-192 (10 gigabits per second) output per wavelength and provides enough capacity to move to OC-768 (40 gbps) and beyond via software upgrades in the future, said Mukesh Chatter, vice president and general manager of IP products at Lucent.

The "NX64000" router sets the stage for a rapid transition to tight integration with the optical domain, Chatter said. "We have DWDM [dense-wavelength-division multiplexing] optics integrated right in the router, and we are working with our optical-networking group to integrate further," he noted.

The router and optical-networking groups are evolving "to a common control plain between our core terabit-router switch and our new optical switch, where information will be shared between them in the management of optical wavelengths," Chatter explained.

The driving force behind this evolutionary path is efficiency. Even at this point of development, where the company's new "Lambda" optical cross-connect and terabit router are separate units, Lucent claims that network operators can save 25 percent using the two together versus using the router with another vendor's optical-networking equipment.

"Everybody is looking for massive scalability, but the gap between the performance of optics and electronic switching is a problem," Chatter said.

With low latency of 40 microseconds "through the box" and high port density that can accommodate individual ports running at interfaces as low as 155 megabits per second, the new Lucent router provides the quality-of-service support essential for scaling standard IP traffic, including reliable voice over IP.

"This is the enabler for voice or real-time traffic in the core of the network," he said.

Nortel is looking at similar synergies as it moves to acquire Silicon Valley optical-switching developer Xros Inc. in a stock exchange valued at $3.25 billion.

In fact, the parallels between the telecommunications giants'strategies extend to the types of optical-switching techniques they're using. Both involve proprietary but similar lightwave-routing techniques based on tiny, fast-moving mirrors.

"Nortel Networks and Xros share a commitment to implement the vision of the all-optical network, delivering world-class cost of ownership and value for our customers'business needs," said Clarence Chandran, president of Nortel's service-provider and carrier group.

"An all-optical Internet will deliver millions of instant Internet sessions, thousands of video channels and vast amounts of e-business transactions on an unprecedented scale," he added.

Nortel has already moved a long way in the direction of integrating IP routing and optical networking with its "OPTera" line of DWDM systems and the new "Versalar 25000" terabit router.

"The 25000 is part of the OPTera solution portfolio, but you'll need the OPTera packet core as another device with the 25000," said Ed Jasho, group manager for IP infrastructure with Nortel.

That comment points to the tricky part of what's happening as vendors seek to integrate DWDM and core switching technologies. They all are pursuing disparate means of managing the optical layer as they seek to avoid burdening carriers with the overhead penalties of SONET (synchronous optical network), while providing the "five 9s" (99.999 percent) reliability that carriers require.

The players contend that they want standards, but each has proprietary interests that are slowing the process.

"We are committed to a standards-based approach, but the standards aren't resolved yet," Chatter said. "Intellectual property has to be respected and standards have to evolve together, and that's still a pretty fuzzy area. We're much more interested in seeing a consensus emerge than we are in pushing any proprietary approach we might have, but we're not waiting."

After two years of infighting over the optical-management platform among leading providers of transmission systems, the surging significance of IP in all types of communications and the potential payoffs to carriers embodied in interconnecting routers and optical switches has brought industry factions together within a new forum.

The Optical Domain Service Interconnect initiative now has more than 50 vendors and service providers as participants following its first meeting in January.

"It is clear that future data and voice networks will be dominated by terabit IP routers operating over optically switched transport networks," said Ross Callon, chief systems architect for IronBridge Networks, another newcomer to the routing arena that has pegged its fortunes to the success of terabit routing.

Currently, many backbone Internet-service providers experience bandwidth utilization as low as 50 percent because standard IP-routing protocols do not distribute traffic evenly across the networks. "There are tremendous synergies to be gained by coordinating the operation of routers and optical switches, and ODSI provides a way to leverage the bandwidth provided by the optical-transport network," Callon said.

Callon, a co-author of the MPLS (Multiprotocol Label Switching) standard, said the ODSI group will select and apply extensions to recognized industry interfaces and protocols, conduct interoperability testing and promote technical recommendations to standards organizations.

The ODSI mechanisms, coupled with IronBridge's intelligent traffic-engineering features, will enable the company's routers to optimize bandwidth utilization hour by hour across an entire core network, Callon said.

IronBridge isn't just working to ensure connectivity with optical switches on the outside-it is also applying optical technology to the inner workings of its router system, noted Doug Antaya, vice president of marketing for the Lexington, Mass.-based firm.

"We're not talking about our optical architecture in any great detail, but you can assume it has implications for wavelength routing," Antaya said.

The internal optical system is meant to provide a seamless means of scaling traffic from low speeds to terabit speeds, he added.

"To get to terabit speeds, you need to link shelves together in a way that is transparent to the outer network, and that requires an optical interconnection internally," he said.