Cypress to replace content addressable memoryRichard BallCypress Semiconductor is planning to introduce replacement chips for content addressable memories (CAMs) that promise to be cheaper and use less power and board space.
CAMs, particularly ternary CAMs, are the best method of storing packet routing tables in networking products. However, they are becoming very large, up to 18Mbit, and hence very expensive.
An alternative is to use pure software searches such as tree walking, but these are slow and unpredictable, whereas hardware TCAMs are fast and predictable.
Cypress is proposing to use conventional SRAM and better search algorithms in some associated logic or a network processor. This would benefit cost and power consumption, to the slight detriment of speed.
"They will be two to three times lower power than TCAMs," said Amr El-Shimi, product marketing manager at Cypress. "And the searches will be deterministic." The firm would not say how fast the technology would be compared with CAMs.
The comms chip firm gained its new expertise in CAM replacement from its purchase of Sahasra, a five person team based in Silicon Valley.
The result will be a family of eponymous chips that will add to standard six-transistor SRAMs the necessary logic for searching out routing information.
"Sahasra is going to be the ideal solution for multi-million entry search tables," El-Shimi claimed.
The power aspect will be especially attractive to line card developers, where power density is often more important than latency.