Improving Route Lookup Performance Using Network Processor Cache

Earlier research has shown that the route lookup performance of a network processor can be significantly improved by caching ranges of lookup/classification keys rather than individual keys. While the previous work focused specifically on reducing capacity misses, we address two other important aspects - (a) reducing conflict misses and (b) cache consistency during frequent route updates. We propose two techniques to minimize conflict misses that aim to balance the number of cacheable entries mapped to each cache set. They offer different tradeoffs between performance and simplicity while improving the average route lookup time by 76% and 45.2% respectively. To maintain cache consistency during frequent route updates, we propose a selective cache invalidation technique that can limit the degradation in lookup latency to within 10.2%. Our results indicate potentially large improvement in lookup performance for network processors used at Internet edge and motivate further research into caching at the Internet core.