A telecommunications network comprises a plurality of network terminations interconnected through the network, each network termination being connectable to network termination equipment configurable for the input or output of data communicated between the terminations over the network.The data collection and generation equipment is controlled by a central server to generate data required for the monitoring of this performance, such as latency in a connection between two of the terminations. This server has configuration means for controlling a data retrieval means and data processing means to generate the outputs required of it, and is associated with a data storage means comprising means to store data relating to the arrangement of the network and the network terminations. The configuration means identifies, from the network data store, the network terminations required to perform the data collection required and transmits instructions to them to generate this data.Each network termination comprises monitoring means for monitoring the performance of traffic feeds between the network terminations, each monitoring means comprises data generation and collection equipment independent of the network termination equipment, and the data collection and generation equipment is arranged to exchange test signals with other such equipment and to monitor the performance of said signals, under the instructions of the central server.The use of a configuration having monitoring equipment at every network termination, in conjunction with the application of measurements only across those paths where required, allows an improvement over prior art systems in the frequency and accuracy of measurements, and the rate at which measurement data can be collected and disseminated.