The process of converting IP addresses to AS numbers is analogous to the way an IP routers match the longest prefix of the IP address contained in the composite routing table obtained in the prior step. The demand summary [23] for each web server log is a compact file, suitable for sending across the network to a collection point. Each demand summary file contains one line for each AS number that had non-zero requests. The line contains the AS number, the count of successful requests, and the number of bytes in replies.