Passive Optical Gear Vendors Get Active

FRAMINGHAM (07/03/2000) - Remember several years ago when large legacy carriers said they were going to bring "fiber to the home" or "fiber to the curb" but never quite seemed to get there?

Now that most incumbent local exchange carriers (ILEC) have turned to copper-based DSL for broadband rollouts, a new generation of vendors of fibersplitting gear is pushing new carriers to go back to the ILECs' original idea. Only this time, the equipment makers are pushing carriers to offer fiber-based services to business customers looking for local connections of up to 100M-bps.

Say hello to a group of startups promoting the latest in passive optical networks (PON), an old idea that's gaining new life among service providers that see a way to bridge the "first mile" from business locations to the new optical metropolitan networks they don't quite reach on their own.

In PONs, all active electronics are removed between the customer premises and an optical carrier backbone. Instead, a set of splitters chops wavelengths of light into time slots so that each wavelength can be shared by a number of end users.

The market: Some 76 percent of businesses with 75 employees or more are located within a mile of someone's optical fiber, according to market researcher Vertical Systems in Dedham, Massachusetts. That's a much greater percentage than currently can be reached with SONET-based nets.

But the trick with taking advantage of this optical fiber has been to inversemultiplex the end-user connections in a way that offers business users - as opposed to residential customers with less stringent demands - a choice of not only T-1 connections but also native 10/100M-bps Ethernet connections at an economical price.

The first start-up expected out of the gate next month with a deliverable system is Quantum Bridge of North Andover, Massachusetts, which will offer a carrier switch supporting seven PONs of 32 end users each for a total of 224 connections at an aggregate price of US$7,000 per customer.

In Quantum Bridge's system, the service provider installs the vendor's QB5000 optical access switch, which supports a total of 622M bit/sec throughput, says Jeff Gwynne, Quantum Bridge's vice president of marketing. Then, at each customer premise the service provider installs a QB 100 Intelligent Optical Terminal supporting four T-1s plus one 100Base-T interface. The entire system lists for a combined total of $7,000 per end-user site.

Coming behind Quantum Bridge is Terawave Communications of Hayward, California, whose PON system is expected later in the third quarter. Terawave says its optical access switch can support an aggregate of 2.5G bit/sec throughout a set of PONs, although the company has not released prices (Quantum Bridge officials say they plan to upgrade to 2.5G). Then comes Alloptic of Pleasanton, California, which says it will specialize in offering a wider variety of end-user interfaces, including ISDN, DSL, NxT-1, native Ethernet and OC-x.

In fact, fiber-based PONs are not necessarily incompatible with DSL implementations. For the residential market, some ILECs are considering running PONs to the curb and then using DSL over copper to complete the loop, says Andrew Cray, a senior analyst at Aberdeen Group. There are some entirely fiber-based residential PON installations, "but it usually has to be in new residential developments," Cray says.

In both cases, ILECs are testing PON equipment from Lucent, Alcatel and other vendors with close ties to the ILECs. But many of the bigger vendors' products are based on a PON standard developed earlier by a group of about 20 large carriers around the world called Full Service Access Network, which maps traffic shipped over passive optical first-mile links onto ATM backbones. By contrast, "We support ATM on PONs," says Quantum Bridge's Gwynne, "but we also support IP directly on wavelengths."

Ironically, one of the first types of service providers to implement PONs for business customers may be cable companies, ordinarily thought of as serving exclusively residential customers. They are building fiber deeper into their nets, bringing them close to business locations.

But skeptics have pointed out that because PON architectures appear much like cable-modem network topologies - with a certain amount of bandwidth proportioned out from a head-end and shared by end users - there is the potential for user competition and performance degradation.

To deal with this potential drawback, Quantum Bridge will tout a management system which will let service providers offer bandwidth-on-demand.

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