OT>> DWDM Drills Down Toward the Network
Although Dense Wave Division Multiplexing (DWDM), which can significantly
increase the capacity of fiber optic cable, may have gotten its start in the long
distance carrier market, the technology is now filtering down to RBOCs, Local
Exchange Carriers (LECs), MANs, and even individual data centers.
In the RBOC arena, Lucent Technologies and Ciena (Linthicum, MD) are involved in
a project with Bell Atlantic to beef up the carrier's network. Lucent will supply its
WaveStar DWDM system, which enables end-to-end transport of 16 channels of
information. Ciena will provide its MultiWave 4000, which the company says can
support up to 40 channels on a single fiber.
Bill Gartner, vice president of product development for the optical networking group
at Lucent Technologies, says that although DWDM is economical at the long
distance and RBOC levels, it is a harder sell at the MAN, or short-haul, level. In long
distance applications, DWDM technology can often replace multiple repeaters with
a single optical amplifier. In MAN applications that don't involve repeaters,
technologies such as time division multiplexing may win the numbers game,
Gartner says.
On a more granular level, DWDM is being used by a disaster-recovery service
provider. A joint venture of Swiss banks, Real Time Centre (RTC, Bern, Switzerland),
is using Osicom Technologies' (Santa Monica, CA) GigaMux DWDM system to
transmit data for offsite storage.
Osicom's approach is based on DWDM rings over SONET. This is good news for
customers of SONET-based services supplied by providers who aren't particularly
interested in ripping up their entire infrastructure, points out Mark DiMaria, Osicom's
director of product management and marketing.
According to Osicom, the GigaMux can divide each of its 32 wavelengths into 16
subrate channels, which translates to 512 service channels running over a single
fiber.
Despite these market shifts, long distance carriers remain king in the DWDM
sector. Ciena's loss of a contract with AT&T was cited as a major reason for the
cancellation of a proposed acquisition of Ciena by Tellabs (Lisle, IL).
But Ciena isn't sitting on the sidelines. The company is working with Sprint to
upgrade the carrier's Internet backbone to OC-48 (2.48Gbits/sec). The plan involves
directly interfacing Cisco's 12000 series Gigabit Switch Routers to Ciena's
MultiWave 4000, with these interfaces retaining the 2.5Gbit/sec rate.
This approach, says Denny Bilter, Ciena's director of marketing, enables direct
delivery of the data, which eliminates the need for high-end digital switches and
SONET equipment, thus considerably simplifying network infrastructure.
—Elizabeth Clark |
