PROBLEM: At the heart of the Internet are the routers that direct packets of data to their destinations. But by briefly holding each packet in memory while figuring out where to send it, these specialized computers create a bottleneck. The speed of today's 10-gigabit-per-second links forces router makers to use fast but expensive static random-access memory (SRAM) instead of slower, cheaper digital random-access memory (DRAM). As connection speeds increase, the amount of SRAM needed will become prohibitively expensive, leading to data loss and limiting applications such as voice calls and videoconferencing.
SOLUTION: As a graduate student at Stanford, Sundar Iyer created a technique that lets equipment makers combine SRAM with DRAM to make routers at once faster, more reliable, less expensive, and more energy efficient. In Iyer's "perfect caching" scheme, each arriving data packet is stored in an SRAM chip. Once every hundred nanoseconds, the cache sends all the packets to the main memory, made from DRAM. Fifty nanoseconds later, another SRAM cache takes only the packets it needs and sends them to their destinations. Iyer founded Nemo Systems to develop the technology in 2003; Cisco bought Nemo in 2005 and is building the system into its next generation of enterprise routers. --Neil Savage
