Patent ID: 7453820

Claim:
A system for measuring the quality of a data network, the system comprising a client computer and a server computer, the client computer and the server computer being arranged to communicate via the data network using a connection-less transmission protocol, wherein: the client computer is arranged to send data packets to the server computer so as to define transmitted data packets, each of the data packets having a first timestamp indicating a time at which said each data packet was sent to the server computer; the server computer is arranged to: receive at least one of the transmitted data packets so as to define received data packets and send, for each one of the received data packets, a corresponding modified data packet to the client computer so as to define modified data packets, the corresponding modified data packet having the first timestamp from said one received data packet and a second timestamp, the second timestamp indicating a time at which said one received data packet was received at the server computer; and send a timeout data packet to the client computer when a predefined amount of time has elapsed since a most recent one of the received data packets was received by the server computer; and wherein the client computer is further arranged to: store first and second log files with the modified data packets received from the server being stored in the first log file and the timeout data packet being stored in the second log file; store each of the transmitted data packets in a ring buffer; check each of the modified data packets received from the server with contents of the ring buffer; and if one of the modified data packets is not received by the client computer within a length of the ring buffer, delete from the ring buffer a particular one of the transmitted data packets and which is associated with said one modified data packet and store the particular one transmitted data packet so deleted in the second log file.