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The exponential growth in Internet traffic has motivated the development of a new breed of microprocessors called network processors, which are designed to address the performance problems resulting from the explosion in Internet traffic. The development efforts of these network processors concentrate almost exclusively on streamlining their data paths to speed up network packet processing, which mainly consists of routing and data movement. Rather than blindly pushing the performance of packet processing hardware, an alternative approach is to avoid repeated computation by applying the time-tested architecture idea of caching to network packet processing. Because the data streams presented to network processors and general-purpose CPUs exhibit different characteristics, detailed cache design tradeoffs for the two also differ considerably. This research focuses on cache memory design specifically for network processors. Using a trace-drive simulation methodology, we evaluate a series of three progressively more aggressive routing-table cache designs. Our simulation results demonstrate that the incorporation of hardware caches into network processors, when combined with efficient caching algorithms, can significantly improve the overall packet forwarding performance due to a sufficiently high degree of temporal locality in the network packet streams. Moreover, different cache designs can result in up to a factor of 5 difference in the average routing table lookup time, and thus in the packet forwarding rate.

Suez is a high-performance real-time packet router that supports fast best-effort packet routing and scalable QoS-guaranteed packet scheduling, and is built on a hardware platform consisting of a cluster of commodity PCs connected by a gigabit/sec system area network. The major goal of the Suez project is to demonstrate that the PC cluster architecture can be as cost-effective a platform for high-performance network packet routing as for parallel computing. Suez features a cache-conscious routing-table search algorithm that exploits CPU caching hardware for fast lookup by treating IP addresses directly as virtual addresses. To scale the number of real-time connections supportable with the link speed, Suez implements a fixed-granularity fluid fair queuing (FGFFQ) algorithm that completely eliminates the per-packet sorting overhead associated with conventional weighted fair queuing algorithms. This paper presents the architectural features of Suez, and reports the performance measurements of the Linux-based Suez prototype, which is built on four Pentium-II 400 MHz machines and Myrinet.