Despite the promises and optimism from enthusiastic vendors, physicists are still puzzling over how to carry Ethernet frames to dozens - or hundreds - of devices without the Gig-E network looking like a Rube Goldberg contraption. One proposed solution, RPR, is a way to carry Ethernet frames in a token ring configuration while allowing many devices to attach to the common ring. It lets a single set of Ethernet switches read all kinds of traffic on a Gig-E network, while providing the 99.999 percent reliability, the quick restart time and the microsecond latency required by carriers moving both data and voice. But the RPR Alliance acknowledged that acceptance of the standard is at least two years away.The MEFs Klessig said any vendor implementing its proprietary version of RPR is taking a risk because "it will end up having to be changed, almost for sure." Cisco and Dynarc both have versions of the proposed RPR standard, and may have to retrofit if the standards body moves in another direction.By contrast, vendors running their own versions of MPLS are probably on safer ground. "Theyre quite close on what a label should look like. Its almost cast in concrete," Klessig said. Meanwhile, the 10 Gigabit Ethernet Alliance hopes to win ratification of its standard by spring of next year. Last month, the alliance approved higher-density, lower-cost switch chips and optical transceivers that will allow a single chip to support many 10 Gig-E ports. Sigma Networks offers both SONET and Gig-E to its service provider customers, and hopes to expand into Dallas, Los Angeles and New York by years end. Venture capitalists rewarded the companys business plan - which is based on offering both SONET and Gig-E - with $400 million early this year. Most of Sigmas customers are sticking with SONET traffic, typically asking for 622 Mbps, said Sigma CEO John Peters. "Our customers are all interested and want to learn more about Ethernet. [They] want to offer it to their enterprise customers," Peters said. "But were not seeing a huge groundswell of energy to deploy those services yet. There are two issues with Gigabit Ethernet - robustness and overall reliability. For many applications, that reliability and robustness still drive a SONET-based solution. That gap will close over time, though. "Ive been in the communications business for 25 years, and every few years something comes up that is going to be the answer to world hunger. Ethernet isnt that answer. But it is a great protocol for an appropriate set of applications," Peters added. Ovums Main agreed, saying Ethernets promise to deliver a cornucopia of services is unproven. The early adopters base their optimism on MPLS ability to sort traffic and give a higher priority to, say, voice and video, and a lower priority to e-mail and data. "MPLS is probably the right way to go, but right now its proprietary," Main said. "Theyre deploying networks based on half-finished implementation of MPLS. Theres an advantage to being first to market, but theres also the risk of getting it wrong, of backing the wrong horse."