Networks: Terabit Routers Take on Networking's Heavy Lifting

Posted: 06/1999

Terabit Routers Take on Networking’s Heavy
Lifting
By Charlotte Wolter

The very phrase terabit router has an awesome ring, conjuring images of huge streams of
data under the control of a powerful, fast machine. Indeed, terabit routers–which will
switch 1 trillion bits per second and more–will sit at the hearts of some of the largest
networks operating today or planned for the future.

The terabit router market breaks down into two camps, says Chris Nicoll, director,
infrastructure, Current Analysis Inc., Sterling, Va. One is simplifying the design of an
Internet point of presence (POP). Some Internet POPs today have become hodge-podges of
routers and asynchronous transfer mode (ATM) switches linked by limited OC-3 connections.
These can be replaced by a single terabit router, Nicoll says, but it will have to have
the ability to handle huge numbers of routing table lookups and to aggregate many
lower-speed lines.

The other application is making an Internet backbone larger, faster and more scaleable.
For this application, a router needs high horsepower, low delay and a high-throughput
architecture.

Pipe Power

Terabit router makers are confident that there will be a market for their products,
fueled by sheer demand for bigger and bigger pipes. Peter Chadwick, director of marketing
for Avici Systems Inc., a Chelmsford, Mass.-based startup making terabit routers, says the
genesis of his company was the advent of wavelength-division multiplexing (WDM). With
multi-terabit streams on one fiber, but only gigabit routers, the question was: "Were
they going to end up with pipes that they can’t fill?" Chadwick says.

Graph: Multigigabit Router Forecast, 1998-2003

According to Avici, the company polled its potential customers for their anticipated
traffic demands, and got estimates of growth from five to 10 times current capacity per
year. Projecting to 2001, Chadwick says, the company believes there will be many POPs with
traffic in the 4-terabit range.

The rapid development of networks and network technologies will fuel tremendous demand,
says David Passmore, research director, NetReference, Sterling, Va., a network consulting
firm. Not only are network companies laying down vast numbers of fibers, but, with WDM,
each fiber will be carrying multiple OC-48s (2.5 gigabits per second [gbps]). The number
of WDM channels per fiber will continue to scale from 40 today to more than 100 in the
future. Also, as the size of synchronous optical networking (SONET) multiplexers grows,
each channel will scale from today’s OC-48 to OC-192 and, in a few years, OC-768.

"So what [to] do with those channels, if that number of OC-48s come out of a
single fiber, what can go fast enough?" Passmore asks. "The answer is terabit
routers."

Another factor favoring larger-scale routers is that today, smaller routers are
clustered to handle growing traffic. As a result, however, they waste a significant amount
of processing just passing packets back and forth among themselves instead of to the
outside world.

Davids and Goliaths

In an indication that large telecom vendors are moving into this space, Nortel
Networks, Richardson, Texas, has unveiled a terabit router that is its original equipment
manufacturer (OEM) version product from Avici, a company in which Nortel has made a
substantial investment. Nortel says the product, the 45000 Terabit Router, will scale to a
throughput of 45 terabits per second (tbps) and is aimed at large Internet service
providers (ISPs) and managed Internet protocol (IP) network providers that will use it in
the core network to connect to other service providers or large-scale POPs.

Avici is one of a clutch of innovative startups that includes Argon Networks,
Littleton, Mass.; Juniper Networks Inc., Mountain View, Calif.; Netcore Systems Inc.,
Wilmington, Mass.; Nexabit Networks Inc., Westborough, Mass.; and Pluris Inc., Cupertino,
Calif.

Other larger players also are weighing in. Newbridge Networks Corp., Kanata, Ontario,
plans to have a product by the end of the year. The newly merged Ascend Communications
Inc., Alameda, Calif., and Lucent Technologies Inc., Murray Hill, N.J., are expected to
join the market shortly, and Cisco Systems Inc., San Jose, Calif., the dominant player in
gigabit routing, is reported to have an internal development project.

These players differentiate themselves on whether they truly are IP internally or
whether they use ATM cell switching. Argon and NetCore use ATM internally. An argument in
favor of an ATM approach, Passmore says, is that the current infrastructure is largely
ATM, which makes for simpler interfaces.

Also, "The ATM routing protocol, PNNI (private network-to-network interface), is
more sophisticated in allowing you to respond to congestion in the network," Passmore
says. "One of the complaints about IP routing is that routers are dumb and send
traffic over shorter but more congested paths rather than longer, freer paths."

Another key differentiator is scalability. Traffic is expected to move from OC-48s to
OC-192s by mid-2001, Chadwick says, and "providers are tired of throwing out a router
every 18 months, because that is what they have been doing for the last five years."
Sam Halaby, vice president of marketing, Pluris, says his company estimates most POPs will
grow by a factor of four per year, so a POP that is 10gbps this year will be 40gbps in a
year and 160gbps in two years.

Avici’s strategy has been to put together an architecture that allows deployment of a
cost-effective solution today that handles tens of OC-48s, with the ability to scale up to
hundreds of OC-192s.

There is some controversy about the degree to which products are able to scale.
Nexabit, in particular, has raised some eyebrows with its claims of being able to scale
almost indefinitely without having to cluster. Some in the industry are skeptical,
Passmore says, "but all we have to do is wait and see. I can’t imagine that they
would say it if they couldn’t deliver on it."

For other companies, Passmore says, their products operate like a cluster of smaller
routers, just all in one box, which may limit scalability.

Router Ready?

Few terabit routers actually have been delivered. Most vendors will not introduce their
products until later this year or early next year. Juniper has shipped its first product,
as has NetCore, and Avici and Nexabit are in beta testing but close to shipping. Pluris
expects to deliver a product by fourth quarter.

However, Nicoll says the market for routers is limited. "Cisco owns the gigabit
router market, and they have shipped only 1,000 of them over the past two years. Even if
there is a need for a thousand of them, a thousand terabit routers is not two or three
companies’ worth of hardware product for a year, and there are more than a half-dozen
companies approaching this space."

Also, most companies are going after only one segment, he says. "I have a gut
feeling that everyone wanted to build the biggest, baddest router on the market. Even if
there is a need for a bigger, badder GS12000 (a Cisco product), how many do I really
need?"

The clutch of small terabit router startups is likely an endangered species, at least
as standalone companies. With the large traditional equipment vendors under pressure to
adapt their product lines to the probability that the global network infrastructure will
all go to IP, these companies are likely acquisition targets.

"I expect within the next year every one of these will get acquired,"
Passmore says. "I doubt if any will go to an IPO (initial public offering). We
already saw this with Siemens [Telecom Networks, Boca Raton, Fla.] and Argon, and Nortel
has a major investment in Avici and is likely to acquire the rest."

Charlotte Wolter is infrastructure editor for PHONE+ magazine.