Paths of Least Resistance

While carriers and incumbent service providers have always been a conservative lot, the current economic downturn has prompted carriers to actually escalate their levels of caution regarding the convergence of existing services onto a single backbone.

With the percentage of revenue devoted to capital expenditures and operational costs continuing to rise, service providers are reluctant to make any significant network upgrades that could conceivably cost them even one single customer.

"In offering equipment for moving a carrier to a converged core, you have to offer the path of least disruption," says Chad Dunn, director of product management at startup WaveSmith Networks. "You can't expect them to make a big paradigm shift away from what they are doing."

What they are doing, of course, is supporting all-you-can-eat data services with still-lucrative legacy services, such as ATM, frame relay and private line connections. While these services continue to represent the bulk of a carrier's revenue base, carriers can no longer afford to operate separate networks for each of these services — especially as they continue to pour billions of dollars into infrastructure upgrades to keep up with soaring increases in IP traffic.

"Faced with new carriers coming into the space, incumbents need to reduce operational expenses and compete on services," says Alex Dobrushin, vice president of marketing at Amber Networks. "Carriers have to convert services to run on lower-cost infrastructures."

Carriers, of course, are aware of their predicament. How does one migrate these services to a common backbone without sacrificing performance and reliability, and without forcing customers to completely overhaul their voice and data operations?

But there's good news for anxious carriers, too — namely, the recent availability of dozens of options designed to enable service providers to gracefully migrate multiple services to an IP backbone. While a definitive method of classifying this new breed of equipment has yet to emerge, the products can be roughly divided into two camps: The core and the edge.

Core values

Heavy-duty routers and switches that feed multiple data streams, ATM, frame relay, voice and IP traffic into the optical pipes that make up the public network also tend to fall into two categories. First, there are those that converge all traffic into IP through the use of multiprotocol label switching (MPLS), a routing protocol that gives IP networks traffic-handling attributes similar to those in an ATM network. Another approach is to send multiple types of traffic over optical pipes in their native formats.

Startups Maple Networks and Tenor Networks belong in the MPLS camp. Sean Welch, VP of marketing at Tenor, says that the major benefit of MPLS is that it enables carriers to package private line and ATM traffic in the same stream that's carrying IP packets. As IP continues to become the dominant traffic type on the core of the public network, carriers will be able to reap huge savings by putting lucrative services into the same data stream as Internet traffic.

"If you can take that traffic, put it on a common backbone and amalgamate all other traffic on that backbone, you get a big-time advantage," says Welch. "You can increase the return on invested capital and reduce operating expenses at the same time."

The major knock against an all-MPLS backbone, of course, is that few are convinced that IP has advanced far enough to provide the same reliability and performance that corporations demand for mission-critical data. Tenor maintains, however, that the company has developed a granular quality of service (QoS) mechanism that enables carriers to offer different levels of service, including a premium service that preserves all of the sensitivities of a private line service.

While it is capable of converging all traffic types into an MPLS stream, equipment from startup Equipe Communications is also designed to transport voice and data traffic across the public network in its native form. The company last week introduced the Equipe 3200 Multi-Layer Optical On-Ramp, a core router that also includes the functionality of a Sonet cross-connect. Equipe's approach to services convergence, says Joe Whitehouse, director of product management, is to enable carriers to gradually migrate traffic over to an MPLS-based core.

"The industry knows that MPLS/IP is the future," says Whitehouse. "We're just not sure exactly when the conversion will happen."

In a sense, Equipe's approach comes close to representing the migration strategies of core ATM equipment makers, such as Fore Systems, now part of Marconi Communications, and Newbridge Networks, now part of Alcatel. Both companies have amalgamated MPLS support into their hardware, providing carriers with the ability to move legacy traffic to an IP core at their own pace.

Life on the edge

At the edge of the network, closer to the customer-facing access gear and multipurpose ATM switches and IP routers, sits a new breed of multiservice switches. These products, from Gotham Networks, Celox Networks, Amber Networks, Juniper Networks, Cisco Systems, Nortel Networks, net.com, WaveSmith and others, essentially do the same thing as core switches. But the big difference is that they tend to deal with smaller tributary pipes coming into the box.

Given their position in the network, however, these boxes tend to be a bit more flexible than those in the core. While most can wrap all sorts of traffic in an MPLS data stream, a few are able to funnel traffic to a variety of backbones, including ATM. And given the changing nature of traffic patterns close to the network's edge, several of these boxes have adapted architectures that provide carriers with the ability to match switching resources with fluctuations in traffic patterns.

Both net.com and WaveSmith, for example, offer separate data and control planes. Similar to the disintegration of hardware and software that is at the center of the softswitch movement, providing independent hardware and software planes essentially enables carriers to mix and match protocols and signaling software without the need to upgrade switching fabrics.

"You can have a full-featured ATM switch initially and later on move to a fully functional MPLS edge switch," says WaveSmith's Dunn. "It's really hard to do that if you don't build something open and programmable."

Startup Gotham Networks recently introduced its "switchless switch." By distributing a switching fabric to every line card, Gotham's gear makes it possible for service providers to configure any port in the system to carry any type of data in its native form.

While service providers have been on the brink of moving legacy services to a converged core, they've been understandably reluctant to make the leap. Analysts suspect that the new crop of multiservice edge and core gear will be just the thing to give cautious carriers a friendly shove.

Copyright © 2004 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in The Net Economy.