Nortel Networks Corp. (NYSE/Toronto: NT) is the latest of several vendors to proclaim CWDM (coarse wave division multiplexing) as a new feature for enterprise use (see Nortel Enhances Metro Portfolio) -- raising questions about this rising trend in optical marketing.

As a "cheap and dirty technology" in the enterprise -- possibly for storage applications -- CWDM has a familiar ring to it. Indeed, CWDM has been offered as a multiservice transport option for months by a growing number of suppliers (see CWDM Products Proliferate). Typically, the phrase for "carriers and enterprises" is part of the pitch.

But Nortel says there's something new here. Specifically, it's offering compatibility between the CWDM wavelengths used on the OPTera Metro 5100 multiservice platform (which already has CWDM) and its Passport 8600 Ethernet Routing Switch. The two boxes can now share the same optical link, whereas previously there was no easy way to funnel enterprise Ethernet traffic from the Passport to the 5100's optical channels without extra hardware and costly fussing.

Nortel's CWDM additions offer eight protected wavelength connections for corporate traffic ranging from 16 Mbit/s to 2.5 Gbit/s.

Nortel has also added a new standalone, environmentally hardened filtering unit designed to aggregate multiple CWDM channels from various 5100s in the basements of multitenant buildings or other enterprise locations, linking them to carrier services in the street or at the nearest point of presence.

Nortel spokespeople say they're riding the momentum that has been building around CWDM. Genevieve Beaumier, who works in optical networks marketing at Nortel, says standards approved by the International Telecommunication Union, Standardization Sector (ITU-T) last year -- plus new, pluggable components for CWDM gear -- have opened the way for enterprises to meet growing Ethernet and storage networking requirements.

Similar claims come from Movaz Networks Inc., which has tapped an OEM partnership with Overture Networks Inc. to link voice and video T1 private lines, as well as Gigabit Ethernet and 10/100 Ethernet, to CWDM services on its RAYedge box (see Movaz Unveils Multiservice Platform). Capacity is eight protected wavelengths. Speeds up to 2.5 Gbit/s are supported for CWDM links, though Movaz offers 10 Gbit/s for DWDM.

Movaz says Ethernet's a key factor in making CWDM attractive to enterprises. "They're using a lot of Gigabit Ethernet services," says Movaz spokeswoman Sofia Fang. These enterprises want to link their data and TDM traffic to the same box and save fiber connectivity, she says. CWDM is an obvious solution.

Other vendors of CWDM gear, notably Transmode Systems AB, says CWDM's on the rise among enterprise users. Alcatel SA (NYSE: ALA; Paris: CGEP:PA), while not specifically promoting CWDM for enterprise use, touts TDM connectivity as a key feature of the CWDM gear it announced in March (see Alcatel Joins CWDM Club).

At least one vendor who's offered CWDM for enterprises says the trend isn't a big one. "I believe CWDM is hot primarily because it addresses the biggest issue with Metro WDM deployments today -- COST! It has also recently become part of the ITU standards, and many component vendors are pushing lots of new CWDM products because they see it as a hot area," writes Brian McCann, chief marketing and strategy officer at ADVA AG Optical Networking (Frankfurt: ADV) in an email today.

McCann says ADVA's been marketing CWDM to enterprises for years, but DWDM is still the mainstay of company sales, representing over 80 percent of ADVA revenues. CWDM's distance limits (up to 80 kilometers or so) and its need for lower power makes it attractive chiefly as a point-to-point interim solution for high bandwidth, but inappropriate for ring or mesh networking, he says -- something that's apt to put a ceiling on its scaleability for enterprises as well as carriers.

For the most part, vendors of CWDM gear see it as an adjunct or stepping-stone to DWDM gear, which seems to have better long-term prospects for everyone. And at least one analyst warns that vendors should carefully consider any heavy reliance on the enterprise space for any kind of WDM.

"One thing is certain, a company that needs service provider revenue to stay afloat will have a very hard time making up for that with enterprise revenue," says Scott Clavenna, president of PointEast Research LLC and director of research at Light Reading. He says enterprises typically pay less and need more hand-holding than carriers, so more of them are needed as customers to make up for a dearth of carriers.

Success in selling any kind of WDM to enterprises calls for effective partnerships, Clavenna says, such as the resale agreements ADVA has with storage and next-gen Inrange Technologies (Nasdaq: CMNT) and Fujitsu Network Communications Inc. (FNC).

Approaching CWDM from a different angle, there's evidence that several storage vendors are taking an interest in adding it to their wares. CNT (Nasdaq: CMNT) just added CWDM connectivity to its storage director (see CNT Flings FC Far & Wide). It remains to be seen, though, how this will play out for CNT as regards competition from other storage players -- including Cisco Systems Inc. (Nasdaq: CSCO), which still seems to be arguing about whether the cheaper optics will be a fit for Fibre Channel traffic as storage networking evolves.— Mary Jander, Senior Editor, Light Reading