A method of providing Quality of Service, QoS, models for use in a network, the method comprising: obtaining data describing a plurality of QoS models, each QoS model comprising at least one QoS component specifying a characteristic of network traffic to be provided by the QoS model, and each QoS model being associated with a performance envelope p ± c, where p is a vector of values specifying a model prototype and c is a confidence vector indicating the expected variation in the at least one QoS component specified by the model prototype p; monitoring network traffic to obtain a plurality of indicators, each indicating a characteristic of the network traffic associated with a corresponding one of the plurality of QoS models, the monitoring comprising: collecting data about a plurality of flows of network traffic associated with each of the plurality of QoS models, and determining, based on the data, a QoS vector q, for each of the plurality of flows assigned to that QoS model, and determining an average QoS vector Q for that QoS model based on an average of the QoS vectors q, for each of the plurality of flows; selecting, based on the plurality of indicators, the average QoS vector Q and the performance envelope p ± c, a subset of the plurality of QoS models; and providing data identifying the subset of QoS models to a client device to enable the client device to send data over the network according to a selected one of the subset of QoS models. obtaining data describing a plurality of QoS models, each QoS model comprising at least one QoS component specifying a characteristic of network traffic to be provided by the QoS model, and each QoS model being associated with a performance envelope p ± c, where p is a vector of values specifying a model prototype and c is a confidence vector indicating the expected variation in the at least one QoS component specified by the model prototype p; monitoring network traffic to obtain a plurality of indicators, each indicating a characteristic of the network traffic associated with a corresponding one of the plurality of QoS models, the monitoring comprising: collecting data about a plurality of flows of network traffic associated with each of the plurality of QoS models, and determining, based on the data, a QoS vector q, for each of the plurality of flows assigned to that QoS model, and determining an average QoS vector Q for that QoS model based on an average of the QoS vectors q, for each of the plurality of flows; collecting data about a plurality of flows of network traffic associated with each of the plurality of QoS models, and determining, based on the data, a QoS vector q, for each of the plurality of flows assigned to that QoS model, and determining an average QoS vector Q for that QoS model based on an average of the QoS vectors q, for each of the plurality of flows; selecting, based on the plurality of indicators, the average QoS vector Q and the performance envelope p ± c, a subset of the plurality of QoS models; and providing data identifying the subset of QoS models to a client device to enable the client device to send data over the network according to a selected one of the subset of QoS models.