DWDM not just for carriers any more

The University of Texas will use dense wave division multiplexing (DWDM) technology, mainly used in carrier networks, to solve a looming bandwidth problem between two of the school’s campuses.

The university has a 622Mbps OC-12 SONET link between two sites, but that is filling up as school traffic blossoms to include site-to-site gigabit Ethernet.

One way for the university to increase the speed of the SONET link would be to rip out the current SONET multiplexers and replace the devices with faster boxes that handle 2.1Gbps OC-48. Or the school could string more fibre and build a parallel network. But both options are too expensive to consider, said Wayne Wedemeyer, manager of networking and telecommunications facilities at the university.

Instead, the school is testing DWDM equipment from LuxN Inc. The equipment puts more wavelengths of light on the existing fibre to boost its capacity. While he didn’t have specific numbers, Wedemeyer said DWDM will cost roughly one-third the price of upgrading the SONET gear. Also, the DWDM gear was installed without disrupting the existing SONET connection.

While Wedemeyer said he is just testing the LuxN equipment and may ultimately use another vendor, DWDM technology seems to be the answer.

Wedemeyer installed two LuxN WaveStations, DWDM hardware that can put multiple wavelengths of light on a single fibre.

For the past three weeks, the school has been testing LuxN’s DWDM equipment while keeping its SONET network intact. The fibre carries the SONET as one wavelength of light, while two other wavelengths add extra capacity for new gigabit Ethernet applications.

The existing SONET multiplexes aggregate traffic from the two campuses and frames it as SONET. The SONET ports on the muxes are connected to the LuxN gear, which in turn puts the SONET on the fibre line between campuses.

The LuxN gear also has gigabit Ethernet ports, so it can connect directly to Cisco routers in the university network. During the current trial run, the LuxN gear is connected to two gigabit Ethernet ports on Cisco routers. The WaveStations then put the gigabit Ethernet traffic onto the fibre link along with the SONET. Each gigabit Ethernet channel rides its own wavelength.

Wedemeyer said down the road he could pull out the SONET gear entirely and have the campus traffic aggregated by a router and placed on its own wavelength by a DWDM box.

“I don’t need the SONET on this link any more, so I can use the SONET equipment in other places. We have other fibre rings in Austin, (Tex.,)” he said.

Data traffic between a supercomputer and engineers runs on the new gigabit Ethernet connections. If need grows enough, Wedemeyer can upgrade the current LuxN chassis to add another wavelength to the fibre. “I’m going to have to use this fibre over and over and over again,” he said.

DWDM also lets customers upgrade the speed of the optical connection without replacing the entire optical box, as is done with SONET.

“There are products out there where you just change the optics and go from OC-12 to OC-48,” he said.

LuxN Inc. can be found at www.luxn.com.