Terabit MPLS Switches in the Works

NTT and Accelight Networks have prototypes of all-optical switches based on pre-standard MPLS technology

May 25, 2001

5 Min Read
Terabit MPLS Switches in the Works

A new wave of optical equipment is about to hit the market: large all-optical switches based on the emerging generalized multiprotocol label switching (GMPLS) standard.

Two companies, Accelight Networks Inc., a startup based in Ottawa and Pittsburgh, and NTT Corp. of Japan, are readying such products for the upcoming Supercomm 2001 tradeshow in Atlanta. The products are described as powerful terabit-sized GMPLS switches based on optical cores.

Both companies will demonstrate high-speed switches that use pre-standard versions of GMPLS. The technology is designed to help prioritize and switch traffic from leased lines, optical wavelength services, and Sonet rings. Both companies say their products will be based on switch fabrics that are entirely optical.

By applying the functions of a GMPLS switch to an optical crossconnect, the companies say they'll introduce new capabilities to carrier networks while cutting costs.

"[The product will] make existing photonic networks even more autonomous and flexible," NTT says in its announcement (see NTT to Demo Terabit MPLS Router).

"Core networks are becoming optical, they're moving from ring to mesh configurations and consolidating service and transport functions," Hyong S. Kim, CEO of Accelight, told Light Reading in an exclusive interview at the company's R&D center in Ottawa last week.

Accelight's announcement is no surprise, even though details have been scarce up to now. The company's first announcement of its PhotoniX family of switches is slated for Tuesday, May 29.

NTT's announcement, in contrast, is a surprise. It hasn't been on most analysts' radar as a would-be provider in this emerging space. Officials from NTT were not available for comment.

Some have questioned whether putting an MPLS switch and optical crossconnect in one box isn't overkill -- a hint of the "god box" mentality (see God is Dead). Others question the use of the term "router," on which NTT seems to be intent. But Accelight, for one, says it doesn't intend to replace existing routers anytime soon.

"We support OSPF and IS-IS, but we don't do packet forwarding the way routers do," says Ken McVey, director of marketing at Accelight. "Think of the highway metaphor. You still need on-ramps, like Cisco or Juniper routers. We can work with those devices to direct traffic through the network core."

McVey says the "beauty" of GMPLS is that it offers extensions for IP-based protocols such as OSPF and IS-IS, allowing the network to support traffic that comes in the form of voice circuits, data packets, and optical wavelengths. He maintains that the first release of Accelight's PhotoniX series, the PhotoniX Core Switch 540, will feature packet-over-Sonet at rates to OC192 (10 Gbit/s) as well as gigabit Ethernet. A follow-on release will handle TDM (time-division multiplexing) circuits and grooming of STS1 (51.8 Mbit/s) channels.

The optical networking industry has thrilled to the prospect of bringing so-called intelligent switching and quality-of-service control to the optical layer of the network. But so far, the concept's been thought of as weird science, more fiction than fact.

"A photonic router with a GMPLS control plane? It could be just a really cool science project, but it sounds terrific," says Scott Clavenna, president of PointEast Research LLC and director of research at Light Reading.

Accelight and NTT are among the first to demonstrate products in this space. Other companies, such as Village Networks Inc., are dedicated to the concept, but use a slightly different tack based on an electrical switching core (see Village Unveils "Optical Packet Node" and Optical Taxonomy, page 10).

In contrast to Village Networks, Accelight says it performs optical-electical-optical conversion in its line cards only. At the switch's core the vendor uses a patent-pending technique called "photonic burst switching" to switch and direct multiple streams of light.

Similarly, NTT claims to use "planar lightwave circuit" technology developed at NTT's Science and Core Technology Laboratory Group in Japan for its switch core.

Both Accelight and NTT indicate that the products they'll demo in Atlanta are very early prototypes. "What we'll show at Supercomm is an engineering mock-up," says Mark Milinkovich, VP of marketing at Accelight. The demo will comprise a two-bay system, including the switch module and network processor cards. Primarily, Accelight's out to showcase the box concept, element management system, and GUI for designing services based on wavelengths and packets, he says. The product's interface is based on GMPLS software from NetPlane Systems Inc. (see NetPlane, Accelight Team on MPLS).

NTT says it's readying a three-bay system that combines an MPLS router with IP and Ethernet connectivity with an optical crossconnect that supports DWDM (dense wavelength-division multiplexing).

It's tough to tell ahead of time how the two products differ, particularly since NTT could not be reached at press time to get specific feeds and speeds. But one difference is clear -- NTT supports the increasingly ubiquitous DWDM technology, while Accelight's does not.

"Our box takes DWDM connections and runs them through the core," says Ken McVey of Accelight. "We plan to support integral DWDM in the future."

The future will be the proving ground for both products. Indeed, much remains to be seen and tested. And both will need to support a range of high-end features carriers are bound to require in core products, such as 40-Gbit/s -- still very much "on the roadmap."

NTT has published photographs of the kit it's bringing to Supercomm. And a visit by Light Reading to Accelight's R&D center last week revealed that the company's working full-out on the project. It's transformed an enormous section of its Ottawa office space into a testbed for the bays and cards that will be first unveiled in Atlanta next week.

Accelight plans to start beta-testing its switch late in November 2001, with general availability set for the first half of 2002. No dates for testing or shipment were provided by NTT.

- Mary Jander, Senior Editor, Light Reading
http://www.lightreading.com For more information on Supercomm 2001, please visit the Light Reading Supercomm 2001 Preview Site.

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