July 8, 2004 Nashua, NH -- The Institute of Electrical and Electronics Engineers (IEEE) last week approved the 802.17 Resilient Packet Ring (RPR) standard. The 700-page document, officially known as "Part 17: Resilient packet ring (RPR) access method & physical layer specifications" is the result of nearly four years of work by the IEEE and the RPR Alliance, an industry advocacy group promoting RPR technology and its standardization.
"When we first started this exercise, there was a great deal of concern that this was somehow going to obsolete SONET and displace Ethernet," recalls John Hawkins, chair of the RPR Alliance and senior marketing manager for Nortel Networks (Ottawa, Ontario). "But the Alliance has never been on that page; we've always regarded this as a completing technology, not a competing technology."
RPR is a layer 2 (link layer) technology that enables the efficient transmission of data, packet video, and voice services over existing SONET ring topologies--while providing sub-50 millisecond protection switching for all types of traffic. According to Hawkins, it offers the best of both SONET and Ethernet. "RPR brings to Ethernet the carrier-grade attributes of fiber, and it brings to fiber the cost-effective, packet attributes of Ethernet," he says.
The technology's ability to deliver multiple classes of service is "one of the more interesting aspects of RPR," adds Mannix O'Connor, director of corporate marketing at Corrigent Systems (San Jose, CA). RPR enables service providers to match transport costs to service revenues, he explains. The protocol provides the ability to distinguish between low priority traffic that can be overbooked and high-priority traffic that has to be guaranteed in strict performance. "RPR will work in conjunction with other mechanisms to really guarantee quality-of-service [QoS] in the metro ring," he asserts.
"RPR brings scalability and resilience into the picture, allowing a carrier to offer a variety of services, both iron-clad, bullet-proof kind of services as well as best-effort kind of services over the same infrastructure," adds Hawkins. "Ultimately, it allows the fiber to be used very efficiently because it's packet oriented as opposed to time slot or TDM oriented. RPR enables a single ring of fiber to carry more customers, and that's the value proposition in a nutshell."
Hawkins reports that most of the service providers rolling out RPR today are selling Ethernet connectivity services "with full knowledge that it's ultimately carrying IP [Internet Protocol] packets these days. There are some folks doing Fibre Channel-oriented things, and RPR will carry that as well. But by far the most common one is IP over Ethernet over RPR."
Looking ahead
Now that the IEEE standard has been approved, Hawkins admits the work of the RPR Alliance is "largely done. We haven't made any decisions yet," he says, "but I don't see any activities on the horizon either. We are moving on to sell our individual companies' versions of the solution now."
Alliance members like Nortel, Corrigent, Cisco Systems (San Jose, CA), and Luminous Networks (Cupertino, CA), among others have been deploying pre-standard RPR systems since 1999. They will need to modify those systems to bring them in line with the new standard, but there is plenty of incentive to do so. Several large carriers, including AT&T, MCI, Bell Canda, China Netcom, and KDDI Japan, have already embraced the technology, and the recent standardization should bolster deployment even more.
According to Michael Howard, principal analyst at Infonetics Research (San Jose, CA), RPR is growing at "a phenomenal rate." Worldwide RPR revenue reached $323 million in 2003, but Howard predicts it will grow 200% to net $967 million by 2007. "Service providers are figuring in RPR over SONET/SDH plans much more now than they were even six months ago," he reports. "In fact, 63% now say they plan to offer Ethernet services over RPR in the next few years."
--MJF