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December 16, 2002

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   Doug Ramsey, (858) 822-5825 or


Kenneth Yun invented a new type of network switching architecture that is scalable from today’s high-end bandwidth of 40 gigabits per second (Gbps)—to more than one terabit (i.e., 1,000 gigabits) per second. His timing seemed perfect: when the professor-turned-entrepreneur set up a company in 1999 to commercialize the technology, demand for bandwidth seemed to be expanding exponentially. Telecom companies were laying optical fiber everywhere they could. Then tech stocks collapsed, and with them, equipment spending on bandwidth. The future, on which Yun’s ultra-high-speed switching technology was predicated, didn’t materialize on schedule. “Telecom companies have refrained from investing in new technology during this period, especially technology that’s designed to support much greater bandwidth,” says Yun, a professor of electrical and computer engineering at the University of California, San Diego (UCSD) Jacobs School of Engineering. “But I see changes coming; there is growing interest.”

There is also a real product to show buyers. It’s called the nPX8005, and it’s made by San Diego-based Applied Micro Circuits Corp. (AMCC), a world leader in high-bandwidth optical networking circuits. The company—where Yun is now employed — is in the latter stages of development of a high-end switch fabric that is based on the academic’s architecture. (A switch fabric combines hardware and software to move data coming into a network node out by the correct port to the next node in the network while maintaining the quality of service requirements imposed by subscribers.)

The nPX8005 is a four-chip set that will be capable of prioritizing incoming traffic into eight classes of quality of service (QoS) and switching it accordingly. The device would be used for high-speed network core switching, but also in metro and access networks. Most importantly, the technology conceived by Yun is scalable, suitable for user bandwidths ranging from just 10Gbps (OC-192), up to 128 times that bandwidth, or 1.28 terabits per second (Tbps). “It is the first terabit-scale switch fabric on the market,” notes Yun proudly.

The nPX8005's architecture is protocol-agnostic, offering cell sizes optimized for cell traffic or packet traffic. Of the four chips on the device, the crossbar chip handles the switching of data, and includes an arbiter to prioritize transmissions. “The crossbar technology is what allows the switch to scale linearly to terabit-range bandwidth for high-end applications,” says Yun, adding that scaling up comes “without inefficiency in power, board area or cost.” Part of Yun’s innovation was the decision to surround the switch fabric with queues with capabilities to schedule traffic flow in a highly differentiated manner—scheduling devices that execute earliest deadline first queuing (EDFQ) for outgoing traffic, and priority queuing (PQ) for both incoming and some outgoing data. The backplane holding the switch together is designed to carry one packet per link rather than "striping" packets across multiple links. This adds to reliability, allowing faulty links to be shut down without affecting others.

Kenneth Yun has a major financial stake in the commercial success of the new AMCC chipset. In 1999, he took a leave of absence from the Jacobs School to create a new company with his investment-banker sister, Kay. Barely six months later, they sold that company—YuniNetworks, Inc.—to AMCC.

He hopes to hit another technology home-run. Yun thinks the barriers between wireless carriers and optical fiber networks must be broken down—allowing wireless services easy access to fiber bandwidth to offload data on routes where wireline service is more available and economical. The Jacobs School professor is working on technology that could lift that barrier and make it easier for wireless and fiber operators to share each other’s networks. Yun, though, says he is not yet ready to talk about this new technology in detail.

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