Nortel Nortel Nortel University of Wuerzburg This document proposes a mechanism for admission control and flow termination. It is based on the concept of pre-congestion notification (PCN) using three different codepoints: "no pre- congestion", "admission-stop", and "excess-traffic" for packet marking. Therefore, the proposal is called three state marking (3sm). The behaviour of edge nodes is presented which distinguishes from other proposals through little complexity and its ability to cope with multipath routing. Algorithms required for packet metering and marking are explained in detail.