Using signatures to improve URL routing

Devices which forward or route at layers higher than the IP layer are emerging to support growing World Wide Web content distribution networks (CDN). URL routing can be used to forward or redirect a client HTTP request to the nearest or otherwise best content source. We develop and evaluate a new look-up method that uses fixed-length URL signatures based on CRC32 coding of URL. The use of URL signatures results in smaller update messages, smaller routing tables, and faster lookups for URL routers. We show how the circuit used to generate an Ethernet packet CRC32 can be simultaneously used to generate the CRC32 of a URL within an HTTP request. We evaluate signature collisions, CPU resources needed to generate signature URL lists, URL list size, look-up performance, and TCP connection performance using nine representative server and cache traces. Signature collisions occur for a negligible number of URL. Signature-based URL lists consume ten times less memory and have look-up rates five to ten times faster than when using full-URL.