A processing node (22, 24, 26, 28) for processing data items in a data network, said data items having path characterisation metrics associated therewith; said processing node comprising: means for receiving data items; means for receiving path characterisation metrics associated with said data items, and for identifying characteristic values in respect of said data items; and a process selection means for subjecting data items to one of a plurality of different processes (808, 809); characterised in that said characteristic values identified in respect of said data items are identified from the path characterisation metrics associated therewith, and in that said process selection means comprises: deriving means for deriving a collective value from characteristic values identified in respect of a plurality of said data items; comparing means for comparing characteristic values identified in respect of each of a plurality of said data items with a predetermined target value; means for subjecting data items in respect of which the characteristic values are on a first side of said predetermined target value to a first process; selecting means for selecting, according to a predetermined selecting function dependent on said collective value, at least some of said data items in respect of which the characteristic values are on a second side of said predetermined target value; and means for subjecting the selected data items to a second process, said second process being different from said first process. means for receiving data items; means for receiving path characterisation metrics associated with said data items, and for identifying characteristic values in respect of said data items; and a process selection means for subjecting data items to one of a plurality of different processes (808, 809); characterised in that said characteristic values identified in respect of said data items are identified from the path characterisation metrics associated therewith, and in that said process selection means comprises: deriving means for deriving a collective value from characteristic values identified in respect of a plurality of said data items; comparing means for comparing characteristic values identified in respect of each of a plurality of said data items with a predetermined target value; means for subjecting data items in respect of which the characteristic values are on a first side of said predetermined target value to a first process; selecting means for selecting, according to a predetermined selecting function dependent on said collective value, at least some of said data items in respect of which the characteristic values are on a second side of said predetermined target value; and means for subjecting the selected data items to a second process, said second process being different from said first process. deriving means for deriving a collective value from characteristic values identified in respect of a plurality of said data items; comparing means for comparing characteristic values identified in respect of each of a plurality of said data items with a predetermined target value; means for subjecting data items in respect of which the characteristic values are on a first side of said predetermined target value to a first process; selecting means for selecting, according to a predetermined selecting function dependent on said collective value, at least some of said data items in respect of which the characteristic values are on a second side of said predetermined target value; and means for subjecting the selected data items to a second process, said second process being different from said first process.