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BURNABY, B.C. - PMC-Sierra Inc. is following up its SmartPath RISC controller for Ethernet switches with a new bus architecture and switching-fabric design. The bus and switching fabric let switched LAN networks scale from Layer 2 bridging to complex Layer 3 routing, with packet-prioritization features added as necessary.
Exact bus is a unidirectional ring operating point-to-point at 125 MHz. It runs at full-duplex speeds of 1 Gbit/second and can scale up to 32-Gbit/s aggregate bandwidth. The bus uses independent 10-bit transmit and receive data paths and has separate transmit and receive clocks.
Chips to implement port-control and packet-forwarding functions won't sample until spring, but PMC-Sierra said it is unveiling the bus architecture now to aid OEMs in developing systems that can scale from Layer 2 to Layer 3 functions.
The company moved into frame switching in September 1996 when it acquired the remaining assets of BIT Inc. (the former Bipolar Integrated Technology), which had an Ethernet switch based on a programmable RISC core. In April, PMC introduced the first derivatives of the BIT line: the EtherDirector and SmartPath architectures for simple 10-Mbit Ethernet switching.
Vern Little, director of Ethernet-switch marketing, said the Exact system bus leverages the programmability of the RISC core to offer advanced packet prioritization and Layer 3 routing at price points more typical of lower-end desktop switches from such vendors as Texas Instruments Inc. and Galileo Technology Inc. Though pricing has not been set on chip sets for the new...