Sometimes smaller is better. At least, that's what a handful of big U.S. carriers say they want in a next-generation broadband remote access server (B-RAS).

BellSouth Corp. (NYSE: BLS), Verizon Communications Inc. (NYSE: VZ), SBC Communications Inc. (NYSE: SBC), and Bell Canada (NYSE/Toronto: BCE) have been hard at work over the past year developing a new DSL Forum specification called Working Text 81, or WT-081. This document, set to be ratified at the DSL Forum's September meeting in Boston, calls for a smaller, less expensive device that can be deployed close to the access portion of a carrier network.

"What's been developed here is a new architectural model," says Bernard Dugerdil, vice chairman of the DSL Forum's WT-081 technical committee. "The key element is the B-RAS, which sits as close to the DSLAM as possible."

The push for a new network architecture has many vendors scrambling to reposition existing products to fill a new architectural void. But some experts say vendors of traditional B-RAS products shouldn't go too crazy retrofitting their gear, as carriers may find that pushing the B-RAS out this far in the network could create some unforeseen challenges.

"The movement to smaller and cheaper devices closer to the DSLAM is a knee-jerk reaction, not a no-brainer," says Graham Beniston, principal of Beniston Broadband Consulting. "It's really trading one set of issues for another."

Historically, B-RASs have been big boxes that sit deep in carrier networks collecting traffic from multiple DSLAMs (DSL access multiplexers) at the points where DSL connections fan out to customers. They terminate point-to-point protocol (PPP) sessions and sometimes also incorporate edge router functions, enabling them to shunt traffic on and off the carrier's IP backbone. They maintain quality of service (QOS), enforce class of service (COS), provision services, and provide a central collection point for data that can be used to bill customers for their network and service usage.

Vendors offering this type of equipment include Cisco Systems Inc. (Nasdaq: CSCO), CoSine Communications Inc. (Nasdaq: COSN), Juniper Networks Inc. (Nasdaq: JNPR), Laurel Networks Inc., and Redback Networks Inc. (Nasdaq: RBAK).

As noted, WT-081 envisions these big boxes being superceded by a greater number of smaller, smarter ones, sitting next to DSLAMs or, in some cases, integrated with them. The goal is to help carriers cut infrastructure costs when distributing content such as streaming video, gaming, and multicast applications.

“It’s less expensive for us to deliver these value-added services closer to the customer,” says Bart Hawkins, general manager of new technology introduction at SBC. “The transport cost for moving packets of high bandwidth applications around can be expensive.”

“We can’t put the content directly onto every customer site,” Hawkins adds. “But we also can’t afford to have customer requests traveling back and forth over the whole network every time they want an application. We need to find a happy medium where content is pushed out to the edge.”

Incumbents aren't the only carriers interested in this architecture. Smaller, independent carriers are also interested in seeing more intelligent B-RAS functionality closer to the edge of the network.

“We’re looking to roll out a video-over-copper service,” says Hans Nilsson, president and CEO of Bruce Municipal Telephone System (BMTS), a rural local exchange carrier in Canada. “Taking the content closer to the edge makes running the network less expensive.”

BMTS just signed a contract to replace its DSL gear from Advanced Fibre Communications Inc. (AFC) (Nasdaq: AFCI) with a B-RAS product from Copper Mountain Networks Inc. (Nasdaq: CMTN) (see Copper Mountain Enhances B-RAS).

Vendors are catching on to what the carriers want, and some have developed products that can satisfy these new requirements. Cisco, Juniper and Redback all have smaller boxes, in addition to their large ones, that could be used for this application (see Cisco Pads B-RAS Offering, Juniper Enhances Its Edge and Redback Sharpens SmartEdge).

Copper Mountain and Network Equipment Technologies Inc. (net.com) (NYSE: NWK) also contend that their products get the specifications right. Copper Mountain claims it’s the only vendor to exclusively design a product for these functions (see Copper Mountain Aims for Compliance). And Net.com claims it’s the only one that has native ATM switching. (The specification doesn’t specifically require native ATM switching, but ATM interfaces are required to handle incoming ATM traffic as well as some ATM uplinks.)

Alcatel SA (NYSE: ALA; Paris: CGEP:PA), the DSL market leader, also has a WT-081 development in the pipeline. It's working with Corona Networks Inc. to develop a B-RAS module that will fit inside its recently announced monster DSLAM, the 7301 (see Alcatel Unveils 'Better' DSLAM and Corona Gets a Boost).

But some experts, like Beniston, say that carriers will have to grapple with a different set of issues with this new architecture. Not only will this physically add more devices to the network that need to be managed, but it will also increase the complexity of service management, says Beniston. What's more, pushing content out to several edge devices could create security risks.

"This really shifts the cost and problems associated with dealing with an ATM network to problems of managing a whole host of distributed B-RASs," he says. "The B-RAS is a key element where individual traffic streams come into the network and lose their individuality as they're routed across large thick pipes. Even on a small scale, these are sophisticated systems."

Beniston will be moderating a Webinar for Light Reading on this topic in September. This follows two other Webinars he's moderated on related topics: Next-Gen B-RAS: The Money Makers and Next-Gen DSLAMs.

For a full list of B-RAS vendors check out Light Reading’s Who Makes What: Equipment 2003.

— Marguerite Reardon, Senior Editor, Light Reading