Sycamore Networks Inc http://www.sycamorenet.com today launched an initiative to become a big player in the metro core - backbones that link together points of presence within a city.

It announced a new set of modules for its existing SN8000 long haul gear, claiming that they will give carriers unprecedented flexibility and efficiency in using their fiber infrastructure in cities for a wide range of applications. Those applications include providing high speed links for ISPs and DSLAMS (concentrators for thousands of DSL connections from users), transparent LAN and remote storage services, and the provision of private circuits.

At first glance, Sycamore looks as though it's late to the party. Plenty of other vendors have already announced metro DWDM (dense wave division multiplexing) developments. In fact, some of them are onto second generation products, having discovered that scaling down their long haul DWDM gear didn't deliver a solution that carriers wanted to buy.

At least one other vendor - Sorrento Networks, Inc http://www.sorrentonet.com - has also announced metro DWDM developments that appear to deliver far more aggregate capacity than Sycamore's SN8000 MC, as the metro core version of its long haul product is called. Sycamore says it can handle 86 unprotected OC-48 channels, which comes to a total of 215 Gbit/s. Only a couple of weeks ago, Sorrento claimed it could do 64 OC-192 channels, a total of 640 Gbit/s - three times as much as Sycamore.

However, this isn't comparing like with like, in two key respects.

First, it's one thing to announce products and it's another to deliver them. Plenty of people are skeptical about Sorrento's announcement (see Sorrento Puffs Itself Up For An IPO). Sycamore's equipment, on the other hand, is already in use. "I have production traffic running over this stuff," says Peter Tierney, founder and COO of Millenium Optical Networks, Inc., an operator offering big bandwidth services in New York, based on Sycamore equipment. Why did Millenium pick Sycamore? "They were ready. Nobody else was," says Tierney. (For the record, Tierney doesn't own any Sycamore stock.)

Second, Sycamore's equipment isn't simply metro DWDM. In fact, it's a combination of DWDM and what amounts to TDM (time division multiplexing). In layman's terms, it uses DWDM to deliver lots of wavelengths and uses TDM to carve up those wavelengths into channels of different sizes, so that carriers can pack a lot more services into each wavelength.

This gives Sycamore four big advantages over vendors that simply offer metro DWDM, expecting carriers to use separate Sonet equipment to support connections over wavelengths.

First, it eliminates the Sonet gear, saving costs.

Second, Sycamore's equipment provides much more fine grain control over the bandwidth of different channels. "A lot of competitive solutions use the burn-the-wave approach," says John McIlwaine, Sycamore's product manager. For instance, they force carriers to use a whole OC-48 (2.5 Gbit/s) channel to carry a single Gigabit Ethernet connection, while Sycamore's approach enables them to carry two.

Third, Sycamore's SN8000 MC is suitable for a wider range of environments. In particular, it can be used when carriers have got plenty of fiber and thus don't need DWDM, but could still benefit from packing services efficiently into wavelengths. "The ability to scale, and the ability to drive down the price per channel is terrific compared to Sonet," says Tierney.

Fourth, Sycamore's gear comes with software that enables carriers to manage the whole network as a single entity, provisioning services from a remote console. In comparison, each bit of Sonet equipment typically requires manual configuration, according to McIlwaine . That translates into long provisioning delays because engineers have to make site visits.

In fact, all of these advantages already apply to Sycamore's long haul gear. The new modules announced today add enhancements targeting metro applications. They include a short range laser, which cuts costs, and a "single wave add/drop cassette", which enables carriers to connect more sites using the same fiber. They also include facilities for simplifying the management of large amounts of fiber connections.

Snags? The biggest one is probably that Sycamore's method of carving up wavelengths is proprietary. In other words, carriers risk getting locked in to the vendor. Mind you, much can be said for most optical gear at present, so maybe it's a price worth paying.

by Peter Heywood, international editor, Light Reading http://www.lightreading.com