A migratory path

AT&T is well on its way to a Sonet- and packet-filled future."Sonet will continue to be the transport architecture well into the 21st century, but the levels [to which] you can take it with dense wavelength division multiplexing are the key," says Frank Ianna, executive vice president of AT&T Network and Computing Services.

AT&T is wasting no time putting the latest high-speed fiber in its network. The interexchange carrier has spent about $4 billion in the past three years to convert its 41,000 route miles of fiber to Sonet, and it plans to deploy a 16 DWDM, 40 Gb/s system this year. It will upgrade by testing a 200 Gb/s system later this year and deploying it next year.

The company will be using Lucent Technologies' WaveStar OLS 400G, an 80-wavelength DWDM system. The system includes optical add/drop and gain control to enable channel configurations to be matched with bandwidth demands.

Those demands are being driven by Internet protocol and private line traffic that is escalating 100% every two to three months, and frame relay and asynchronous transfer mode traffic that is growing 100% annually. Given that rate of growth, the data/voice transmission ratio will shift from today's 52% data and 48% voice to 80% data and 20% voice by 2003 to 2004, Ianna predicts. "Eventually, we'll say we don't know [the exact ratio]. Voice can be inside a data packet," he says.

AT&T also has installed 33 self-healing Sonet rings coast-to-coast and will add 25 more by the end of the year. "No other technology on the horizon has the reliability, scalability and quality that Sonet has," Ianna says.

The IXC is leveraging its large fiber rings with those in Canada and Mexico, and with local rings that Teleport Communications Group has in 69 markets across the country. (AT&T announced its acquisition of TCG on Jan. 8.)

AT&T argues that the Bell companies are hindering its entry into the lucrative local market. The Sonet ring strategy is one of several that AT&T has in mind to reach those businesses and residential end users. One alternative is to buy T-1.5 loops from TCG and resell them. TCG has had greater success than AT&T in getting access to incumbent local exchange carriers' central offices, so AT&T is making the end run to set up metropolitan area networks.

AT&T also plans to add local edge switches that initially handle voice calls and eventually data traffic to augment TCG's embedded base of switches. They will be used to keep up with ATM and eventually IP traffic.

At the same time, the carrier is replacing customer premises equipment with network functionality. Its CO service lets the end user migrate to frame relay, for example, without having to install new equipment or change LAN configurations.

It plans to access the end user through unconventional ways, too. That's where Internet telephony, wireless, cable TV and other not-yet-identified systems will come into play. AT&T has announced market trials of its Internet telephony phone-to-phone interstate calling service in Atlanta, Boston and San Francisco, as well as agreements with Infoseek, Lycos, Excite and Yahoo to provide Internet users access to AT&T's traditional and new services, such as voice-enabled chat. It also is introducing tri-modal wireless phones that aim to create a seamless interconnection of local, long-distance and wireless networks, along with e-mail access, voice messaging and other intelligent networking services.

So what will the 21st century network look like? Ianna's thoughts:

* Circuit-switched voice traffic for another 10 years or so as it migrates to packet-based traffic

* An interconnection of the frame relay and ATM networks, and

* IP router technology installed in PBXs, with LANs connected by private lines that run into an IP cloud and then over a virtual IP network back to the carrier.