A method of processing data items received at a network element in a communications network, respective data items having indications of their source (1, 1') and of an intended destination (2, 2'), the method comprising, in respect of data items received at the network element: classifying respective data items of those received into subsets in dependence on their respective source (1, 1') and destination (2, 2') indications; and forwarding respective data items according to a forwarding process; characterised in that the method further comprises: determining respective performance characteristics for the subsets into which the respective data items have been classified, the performance characteristic for a subset being determined in dependence on one or more time measures indicative of a total time taken for data items to travel from the network element to the intended destination (2, 2') for data items of the subset, from the intended destination (2, 2') for data items of the subset to the source (1, 1') for data items of the subset, and from the source (1, 1') for data items of the subset to the network element; and wherein the step of forwarding comprises forwarding respective data items according to a forwarding process dependent on the respective performance characteristics determined for the subsets into which the respective data items have been classified. classifying respective data items of those received into subsets in dependence on their respective source (1, 1') and destination (2, 2') indications; and forwarding respective data items according to a forwarding process; characterised in that the method further comprises: determining respective performance characteristics for the subsets into which the respective data items have been classified, the performance characteristic for a subset being determined in dependence on one or more time measures indicative of a total time taken for data items to travel from the network element to the intended destination (2, 2') for data items of the subset, from the intended destination (2, 2') for data items of the subset to the source (1, 1') for data items of the subset, and from the source (1, 1') for data items of the subset to the network element; and wherein the step of forwarding comprises forwarding respective data items according to a forwarding process dependent on the respective performance characteristics determined for the subsets into which the respective data items have been classified. determining respective performance characteristics for the subsets into which the respective data items have been classified, the performance characteristic for a subset being determined in dependence on one or more time measures indicative of a total time taken for data items to travel from the network element to the intended destination (2, 2') for data items of the subset, from the intended destination (2, 2') for data items of the subset to the source (1, 1') for data items of the subset, and from the source (1, 1') for data items of the subset to the network element; and wherein the step of forwarding comprises forwarding respective data items according to a forwarding process dependent on the respective performance characteristics determined for the subsets into which the respective data items have been classified.