ClassiPl: an architecture for fast and flexible packet classification

Packet classification is a fundamental and critical operation to be performed in networking equipment such as switches and routers. The types of classification to be performed encompass a wide range, from well-understood operations such as route table lookups to complex packet identification involving multiple fields in the packet. Furthermore, the advent of application-aware network devices demand the use of flexible packet classifiers that can handle operations such as pattern searches and regular expression matching. Traditionally, depending on the classification types to be implemented, solutions based on CAMs/TCAMs, special function ASICs, and software-based algorithms have been used. These solutions, while adequate, target specific classification applications. This article describes ClassiPl/sup TM/, a programmable hardware architecture that performs packet classification at OC48c line rates. Illustrations and examples show how this architecture can be used in conjunction with software algorithmic techniques to support the classification needs of a variety of applications from packet switching, forwarding, and filtering to layer 7 applications such as server load balancing. We believe that the ClassiPl architecture is scalable and flexible to meet the needs of a broad class of network applications.