Fast filtering in bridging Ethernet and FDDI networks: a CAM approach

The use of high-speed fiber-optic networks as backbones for lower speed LANS (large-area networks) is forcing the development of high-throughout bridges implementing fast address filtering algorithms. A filtering technique based on dedicated hardware employing CAM (content-addressable-memory) devices for an Ethernet-to-FDDI (fiber-distributed data-interface) bridge is presented. A simulation study shows that, in any reasonable scenario, more than half the search operations succeed in CAM, thus requiring a minimum processor effort. In a heavily loaded LAN this results in an average gain of about 140 μs per received frame