A fully programmable FSM-based Processing Engine for Gigabytes/s header parsing

In this paper we discuss a new architecture, which is deployed for multi-standard packet inspection and basic network processing tasks in a high-performance network coprocessor. Thereby, concepts, architecture, compiler tool-chain and VLSI area estimation for this programmable finite state machine based (FSM-based) Processing Engine, FPE, are presented. The microarchitecture comprises an FSM-controlled instruction sequencing mechanism, a novel register organization scheme and a short pipeline instead of a typical multi-staged processor pipeline. This introduces several advantages for efficient handling of conditional branches and small look-ups. Those advantages can be utilized for packet classification applications. The FPE data path performance is compared to an ARM9-type processor in two exemplary header parsing kernels from the ”CommBench” benchmark suite. According to the results, the presented engine provides a speed-up of 4 to 10 in terms of required computation cycles to the ARM9. Using a 65 nm VLSI technology, the FPE design is supposed to run at clock frequencies up to 2 GHz and requires about 1.8 mm
²
chip area. Based on the specific transition rule memory organization, which is an essential element of the programmable FSM, a memory utilization of around 95% can be achieved. However, the FPE micro-architecture requires a customized code translation chain in order to transfer high-level program code into an FSM representation. Basically, this is achieved by three steps: (1) generation of sequential, assembly-like macro-instructions, (2) scheduling and generation of FSM-based horizontal (parallel) micro-code and (3) organization of respective FSM rules in the ”instruction” memory. Our studies confirm the advantages of the FPE as a fully programmable high-performance header parsing engine.