To map demand into our AS hierarchy, we needed to know the quantity and the composition of client requests that come from each leaf cluster. The simplest case is a web server with a single host name. The incoming traffic are requests to that server and the outgoing traffic are the replies to those requests. To simplify later analysis, we chose the set of requests that succeeded. In this way, the count of incoming requests and the count of outgoing replies were the same. It is a simple matter to total the number of bytes sent in reply to successful requests.