AFC brings packets and fiber to the access network

Oct. 1, 2002

According to the folks at Advanced Fibre Communications (AFC—Petaluma, CA), there are two major trends taking place within the access network: packetization—the migration from circuits to packets—and what the company calls "fiberization," or the expansion of network capacity. At NFOEC in Dallas last month, AFC launched a product designed to fill both needs, the TransMAX 1500, an environmentally hardened, protocol-agnostic, reconfigurable optical add/drop multiplexer (OADM) that will fit anywhere in the network, says the company. Even in outside plant cabinets.

The TransMAX 1500 employs coarse WDM (CWDM) technology to increase fiber capacity in the access space, a technique that is far more cost-effective than new fiber deployment or equipment forklift upgrades, asserts Dan Konkle, senior director of strategic marketing and communications at AFC. "The ITU has already specified eight wavelengths in the 1470-1610-nm range," he explains. "Eight wavelengths carrying, say, 2.4 Gbits/sec per channel really gives you almost a 10-Gbit/sec capacity. We don't feel DWDM is warranted, because capacity is not the big issue—it's cost."

"If eight-wavelength is the degree of scale that you need in a given location, then it's the best fit," agrees Mark Bieberich, senior analyst with Boston-based researcher Yankee Group. DWDM is not often deployed in the access network, he says, because there are other alternatives to bringing fiber to the end user. However, he adds, "I expect to see more CWDM in the access network as fiber-to-the-home and fiber-to-the-curb become more of a reality in service providers' plans. Bringing fiber directly to the end user is certainly a development in the market that deserves our attention."

The TransMAX 1500 also features what AFC calls "plug and play WDM" architecture; it is designed to look and feel like a SONET box. "With typical WDM ADMs, you need to have external cabling to take wavelengths from a filter and pass them over to a transponder; there's a lot of finger work involved," notes Dan Parsons, senior product manager for the TransMAX 1500. "And in some cases, you have to deploy external optical amplifiers to readjust optical levels as they go through the network. But [the TransMAX 1500] is really designed to plug and play. You just put it in your network, and if you're within the optical link budget, all that is taken care of for you. You've got the same GUI, the same provisioning mentality. It's quite different from a typical WDM ADM."
AFC's environmentally hardened TransMAX 1500 supports both new and legacy services while maximizing the existing fiber capacity of the access network.

Protocol-agnostic may be the AFC device's most important feature, contends Bieberich. On a single platform, carriers can run any type of WAN, LAN, or SAN service, from SONET and Ethernet to Fibre Channel and Ficon.

Featuring redundant power and control, a crossconnect-switch matrix, and what AFC claims is a state-of-the-art heat transfer design, the device fits into a single rack unit. It is environmentally hardened, "which means it doesn't need to be in an environmentally controlled central office (CO) or hut. It can sit in one of our outside plant cabinets and endure heat up to 120°," says Parsons, who adds that the device can also sit inside a building that is not air-conditioned or moisture-controlled.

AFC is currently involved in four field trials, "where," reports Konkle, "the equipment has performed flawlessly around three separate applications"—for fiber gain, to reinforce an existing SONET network, and for the delivery of new services.

In a trial where the TransMAX 1500 is being used to reinforce an existing TDM SONET network still carrying circuit traffic, "the SONET network actually plugged into the TransMAX 1500, and we carried the SONET traffic along with new services for the carrier," says Parsons.

Another service provider wanted to run new Gigabit Ethernet services over an existing facility. "They had existing fiber to carry OC-12 links," notes Parsons, "and our solution was much more cost-effective than pulling more fiber. We just put our equipment on the end of the links and carried the existing service as well as the new Gigabit Ethernet service."

In fiber-pair gain applications, the OADM can provide an 8:1 fiber gain using four bidirectional optical channels on a single fiber. "You use electronics to mimic the addition of outside plant facilities," explains Parsons. "It just gives you more channels when you transport without actually pulling in a new physical facility. If you have one fiber, we can make it look like eight fibers."

An undisclosed service provider is currently testing the device as an interoffice-facility transport to increase the fiber capacity between two COs.

AFC faces formidable competition from the likes of Alcatel and Lucent Technologies as well as several startups, which, at press time, had not yet announced products. According to Bieberich, the access network is one of the few areas where service providers are still spending money, and many vendors are refocusing to address this market.

"There is quite a bit of demand for this type of product right now," he observes. "If you take a look at the overall service-provider network and analyze where the bottlenecks are, they are in the access network and at the service-provider edge, not in the core. Carriers have spent a lot of time and money over the last three to five years building out core networks of incredible capacity, but the capacity that reaches the end user is still in need of expansion, and this is one product that fits that need."

The TransMAX 1500 was jointly developed by AFC and Redfern Broadband Networks (San Francisco). Per the agreement, AFC will market the product in North America and the Caribbean/Latin America.