Nortel Networks this week unveils an approach to extending optical services to a broader base of business users. The technology takes advantage of coarse wavelength division multiplexing (CWDM) and other low cost techniques to achieve some of the things commonly associated with pure photonic systems of the future.
“We’re embracing all the trends toward photonic switching over time, but we’re trying to bring the value of all optical operations to the market today,” said Jack Hunt, director of marketing for metro optics at Nortel. “We’re using wavelength switching that we’ve developed in house as part of this solution, but it isn’t a photonic switch.”
The new product suite combines an integrated optoelectronic 80gbps wavelength switching fabric and a CWDM multiservice platform dubbed “OPTera Metro 5100” that is meant to supply a secondary access ring interface with the firm’s widely deployed metro core DWDM OPTera 5200. The two OPTera platforms, via the wavelength switching, work in tandem to allow carriers to extend wavelength services to a handful of end users on a fiber access ring at much lower costs than would be possible using a DWDM ring, Hunt said.
A key goal of the new products is to allow carriers to more effectively leverage their core DWDM rings, where the capacity is 32 protected wavelengths, which means 32 wavelength pairs. With many of those wavelengths going unused, it becomes possible to employ them for the distribution of optical services to smaller enterprises with use of secondary rings, so long as the costs of interfacing the core and secondary distribution elements are low, Hunt noted.
The wavelength switch eliminates the “bookend” style of provisioning wavelengths across such interfaces, where OEO cards precisely matching wavelengths from the core to dedicated wavelengths on the ring make it cost prohibitive for all but very large customers to be served in this manner. Nortel estimates the use of the switch in conjunction with CWDM cuts the interface costs by 45 percent while CWDM provisioning represents a 30 percent per wavelength cost savings vs. DWDM.
The switch sits at the junction between the core and secondary rings, allowing carriers to remotely configure the placement of wavelengths from the CWDM ring onto the core and vice versa so as to maximize efficient use of capacity resources while keeping costs low, Hunt said. Using Nortel’s active per band equalization technology to remotely equalize wavelengths over the core, carriers can provision new customers on the CWDM ring and match their wavelengths to the wavelengths that are best suited to the distance and capacity requirements of the users. That avoids the need for truck rolls and system shutdowns to establish precisely balanced wavelength interconnections, he added.
“The SP has the flexibility to map wavelengths to whatever parameter it wants
to,” Hunt said. “If you want to have the ability to remotely change the path to accommodate changes in customer sites, you can set the system to do that.”
Rather than using tunable lasers to generate the CWDM signals the company uses CWDM filters, which divide the signals taken from the core ring into eight pairs of wavelengths that are distributed to up to eight different users via single channel add/drop modules at the premises. Nortel is also introducing a network modeling tool with the platform that enables point-and-click provisioning of end-to-end optical paths, eliminating the need for planners to configure individual nodes between the end points, official said.
“We’re working with a number of customers who are looking to push the envelope in wavelength services,” Hunt said. “Now that DWDM is in the core, carriers want to leverage that asset.”
