Fast packet classification algorithms I

Abstract

IP routers use packet classification to support advanced functions such as quality of services (QoS), virtual private networks (VPN), firewalls, and access control. The rules used for classifying packets are called filters. A filter is made up of multiple header fields, e.g. the source IP address, destination IP address, protocol type, and/or port number. The packet classification problem is to determine the best matching filter (the highest priority filter that matches the packet's header fields) in a filter database. In real life, a filter database may have over 10,000 filters. The challenge of the problem is the tight real-time requirement. To match the speed of a gigabit backbone router, the packet classification algorithm is required to sustain a throughput of several millions classifications per second.