Irregular Reconfigurable CAM Structures for Firewall Applications

Hardware packet-filters for firewalls, based on content-addressable memory (CAM), allow packet matching processes to keep in pace with network throughputs. However, the size of an FPGA chip may limit the size of a firewall rule set that can be implemented in hardware. We develop two irregular CAM structures for packet-filtering that employ resource sharing methods, with various trade-offs between size and speed. Experiments show that the use of these two structures are capable of reduction, up to 90%, of hardware resources without losing performance.