OF THE LICENTIATE THESIS Author: Mika Ilvesmaki Name of the thesis: On the behavior and performance of the packet count flow classifier Language of the dissertation: English Date of the manuscript: 1.10.2001 Department: Electrical and Communications Engineering Laboratory: Networking laboratory, S-38 Supervisor: Professor Raimo Kantola Pre-examiner: Docent Kalevi Kilkki Flow classification is used in the Internet to find and detect flows of packets that can be handled separately from the rest of the tra#c. The packet flows may receive di#erent service levels or they may be treated di#erently in the network. This work studies a flow classification method where the flows are detected by counting packets on flow candidates. This counting is continued until the packet count threshold is reached and an active flow is established.