Redback Networks' new forwarding engine module for its Subscriber Management Systems (SMS) brings Gigabit Ethernet technology to DSL service, instantly upgrading the device with the swap of an important card.

by Alex Goldman ISP-Planet Associate Editor [September 8, 2003]

San Jose, Calif.-based Redback Networks' SMS 1000 and 1800 can support up to 10,000 subscribers each, and there are about 5,000 of them installed worldwide. When the company announced that its latest upgrade, the XFE Forwarding Engine Module, would provide native Gigabit Ethernet support, we saw speed upgrades potentially happening rapidly in the field, not just in the lab.

The new module uses Irvine, Calif.-based Broadcom's BCM 1250 network processor to deliver packets at speeds that task the world's fastest processors. The change is significant, explains Jim Capiobianco, Redback director of product management. "We have rearchitected the forwarding plane. We're using the fastest network processing system available, and that's more than just a CPU. We use high speed memory and high speed I/O ports."

The unit consists of a control plane, which handles authentication of subscribers, the routing table, and other high level processes. Capiobianco noted that there are limits to the efficiencies that can be achieved in the control plane because the processes it runs involve interacting with networking devices outside the SMS. Although some improvements are possible with faster processors, the control plane gets more efficient as the Internet itself and networking devices are improved.

On the other hand, the forwarding plane handles processes, such as basic IP traffic (including the ISPs' bread and butter: forwarding packets to subscribers), that are contained within the box. Some processes have moved from the control plane to the forwarding plane since Redback released its first product in 1998. Processes on the forwarding plane can be made more efficient as processors improve.

Capiobianco says that Redback regularly enhances speeds in this area by twenty to thirty percent. In contrast, today's announcement improves packet delivery speeds by two to three times. The actual improvement depends on the size of the packet, with delivery of larger packets seeing a greater improvement than the delivery of smaller packets.

The modular design of the Redback's products makes upgrading relatively easy. Enthuses Capiobianco, "you just swap out the old card, put in the new one, reboot the system, and you're off and running again."

The speeds required for Gigabit Ethernet processing are so extreme that Redback had to go around its own backplane, the part of the appliance that has the largest bandwidth because it aggregates all activity in the box and passes traffic from one part of it to the other. The backplane has to be able to handle the aggregate of all processes on the appliance. Redback chose to go around the backplane and deliver Gigabit Ethernet packets directly from the module to the Internet.

As service providers upgrade their networks, they move from traditional ATM networks to IP-based networks, and are able to offer more services. Notes Shailesh Shukla, Redback vice president of marketing and business development, "there are about 50,000 DSLAMs deployed in the world, but most are dumb layer 2 ATM DSLAMs. If you want to offer [value-added services], they don't have the QoS or multicast capabilities."

IP networks can support more sensitive applications. Jokes Shukla, "games, for example, are sensitive to jitter, delay, and latency. Gamers find that their signal may affect how well they do in the game—if there's delay, they could die!"

Adds Capiobianco, "as soon as we saw young people using gaming, we also began to see a demand from parents for parental control of gaming."

Videoconferencing and other high-level services are also sensitive to network problems.

The bottom line with IP services, of course, is money. Says Shukla, "services improve profits, not just revenue. Services are offered via software with no significant additional infrastructure cost. If the service is worth $2 per month per user in revenue, that may not seem like a lot, but $2 per user per month in profit is a lot."

Capiobianco enthuses, "value-added features can provide up to a 65 percent profit margin because no new infrastructure is required. Service providers are just using the infrastructure better."

Pricing and availability
The XFE Forwarding Engine Module is available now. Redback has subjected it to six months of beta testing followed by six months of deployment in its top of the line SMS 10000. Today's announcement brings the module to the more commonly deployed SMS 1000 and SMS 1800.

Pricing was not available at press time. Redback is offering a "Redback technology migration program" in which service providers will get credit for their old cards.

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