METHOD AND ARRANGEMENT IN A PACKET SWITCH FOR CONGESTION AVOIDANCE USING A COMMON QUEUE AND SEVERAL SWITCH STATES

摘要

A packet switching network has switches and sending/receiving entities interconnected by links (L6) utilized as paths between different users. A switch has an ingress part (I1) with a buffer including virtual queues (VQl, VQ2, VQ3). These are connected to the link (L6) and to a switch core. The queues have threshold detectors (TH1, TH2, TH3) and are connected to states (STA - STD). When the queue (VQ1) is congested by packets the path occupying the individually greatest part of the queue is noted. If noted for the first time the path is stored in a free one of the states (STA,1,2) and corresponding sending entity is halted (XOFF). If the same path is noted again on repeated congestion a bandwidth value (3) is counted up. A chronological order for the states (STA-STD) is established. When all states (STA-STD) are occupied an older half of the states is selected, the path with the lowest count value is further selected, its state is purged and the corresponding sending entity is released (XON).