The battle over the future of high-speed data came to the ComNet computer networking convention last week in Washington, DC - and the telco-friendly xDSL (digital subscriber line) troops showed up in overwhelming numbers.
So many companies were touting xDSL "solutions" that it was hard to tell where the copper ended and the network of tomorrow began. For once, the usually loud hype about cable modems was but a whisper.
But when it came down to the face-off between cable modem and xDSL, the war took a strangely congenial turn, with advocates from both sides admitting that the two extremely divergent technologies will co-exist in peace and harmony.
Cable modems, they say, will be the high-speed spigot of choice in the home. xDSL will reign in the corporate world of telecommuting and videoconferencing, where bandwidth reliability is, as they say in the business, "mission critical."
Nodes and big pipes
Cable modems are designed to work over a hybrid fiber optic-coaxial cable (HFC) network, which is the upgrade design of choice for cable TV companies. But cable modems work off of individual "nodes," each shared between hundreds of homes. If a bunch of teenage boys all try to download the latest Pamela Anderson screensaver at the same time, transmission speeds suffer for everyone using that node.
Of course, cable modem advocates point out that their boxes are so zippy (some cable modems claim 40 megabits per second downstream) and computer processors so limited in comparison (most can only handle about 2 to 3 Mbps), that no one will notice.
The xDSL technology, on the other hand, offers generally slower speeds than cable modems but - because xDSL is tailored to work over dedicated telephone lines - it can guarantee a speed that won't change when the network gets crowded. The dedicated architecture also allows for easier separation of the upstream and downstream paths, often allowing xDSL to offer a more symmetrical data link for two-way business applications.
Several kinds of xDSL species have emerged. But with most Internet activity now centered on the path to the user, asymmetrical digital subscriber line (ADSL) technologies are currently in vogue. ADSL generally opens a wide pipe on the downstream path, with a more modest upstream line.
ISDN burned the telcos
At one ComNet panel last week, at least two experts said the pros and cons of the two technologies will save both of them. Jef Graham, vice president of the mobile products division and general manager at cable modem maker 3Com Corp., said cable modems will likely reach markets before xDSL, giving the company an early advantage. But he added that cable TV operators' sporadic rollout plans will make marketing the service difficult. He noted that questions linger about whether cable TV operators will be able to offer adequate customer support.
But Graham also pointed out that telephone companies have "gotten their fingers burnt" with ISDN services, which some feel haven't produced revenues adequate to justify installation, maintenance costs, and the burden on the public switched telephone network (PSTN). ISDN's history may further repel telcos from deploying xDSL, he predicts, even though xDSL uses a separate packet-switched network and doesn't clog the PSTN.
"The faster they deploy ADSL, the faster they deploy cable modems," Graham said. "And the faster they deploy cable modems, the faster they deploy ADSL." He predicts that cable modem deployment will reach 9 million homes by 2000.
Perry Lindberg, an xDSL guru at Pairgain Technologies Inc., says much depends on the evolution of the Internet and how people will use it. "The more symmetric the application, the more the telcos win... The more asymmetric the application, the cable companies tend to have the advantage," he said.
In addition to xDSL's use of a dedicated line, Lindberg cites telcos' "star topology" architecture that many believe makes it easier to locate problems in the network. Cable TV operators, on the other hand, mostly use the "tree-and-branch" architecture, which he claims makes it more difficult to track down gremlins chewing at the wire.
The great congestion debate continues
As this debate rages on, however, xDSL vendors are using the equally heated Internet congestion debate to buoy their own products, which they said could help resolve whatever congestion may exist on the PSTN.
Telcos have insisted that Internet use is putting wear and tear on its switches and routers, while skeptical computer forces have pegged those complaints as an underhanded attempt to extract more money from ISPs. Although the jury's still out on which version of the truth qualifies as fact, the vendors aren't waiting around to find out.
AG Communications Systems, a joint venture of Lucent Technologies Inc., and GTE Corp., touted its own answer to the alleged Internet congestion using ADSL (asymmetrical digital subscriber line) technology. The company says its ATIUM GateWay product is "the first end-to-end ADSL product" and has received positive reviews at the two military bases where it's already deployed.
Meanwhile, Toshiba Corp. announced a next-generation Internet protocol (IP) switch. Toshiba's gadget allows users to switch between a "topology" approach - in which bandwidth is predetermined before the transmission - and an "on-demand" approach to "allow the allocation of the correct service level for each application."
And newcomer Diamond Lane Communications Corp. - formed in 1995 - was hawking its Hitchhiker ADSL system, which it says would allow telcos to sell Internet junkies on download speeds of 6 Mbps. It's designed to work with ATM (asynchronous transfer mode) technology, which prioritizes data packets to use every available swath of capacity. The hitchhiker is scheduled to hit the road by this summer.
But before you get too excited about any of these xDSL "solutions," remember that none of them will reach the Joe Consumer camp for quite some time - if ever at all. It's up to the telcos that buy all these neat new widgets to decide how to roll them out.
Given a choice between bringing xDSL to money-soaked businesses or trying to wring cash out of residential markets, telcos likely will hit the corporate wallets first. So just as the experts predicted, your high-speed hunger may ultimately hinge on cable companies and their wondrous modems.
