fic bursts and drop traffic unnecessarily. The packet drop probability is based on the minimum average queue length threshold minth, maximum average queue length threshold maxth, and maximum dropping probability maxp. Figure A.4 summarizes the packet drop function. A.5 Random Early Detection and Weighted RED Drop Probability Average Queue Length Figure A.4: RED Packet Drop Function When the average queue length calculated according to equation (A-1) is above the minimum average queue length threshold minth, RED starts dropping packets. The probability of packet drop increases linearly as the average queue size increases until the average queue size reaches the maximum average queue length threshold maxth. When the average queue size is at the maximum average queue length threshold maxth, the probability of packet drop reaches the maximum dropping probability maxp. When the average queue size is above the maximum threshold, all packets are dropped. The minimum threshold value should be set high enough to maximize the link utilization. If the minimum threshold is too low, packets may be dropped unnecessarily, and the transmission link will not be fully used. The packet drop probability Pn of the nth packet arrival is calculated in equation (A-2). Weighted Random Early Detection (WRED) uses the same parameters as RED, but it has the ability to perform RED on traffic classes individually. WRED generally drops packets selectively based on IP precedence. Edge routers assign IP precedences to packets as they enter the network. WRED uses these precedences to determine how it treats different types of traffic. Packets with a higher IP precedence are less likely to be dropped than packets with a lower precedence. Thus, higher priority traffic is delivered with a higher probability than lower priority traffic. However, WRED can be also configured to ignore IP precedence when making drop decisions SO that non-weighted RED behavior is achieved. Appendix < min, (A-2) A.6 AMR The AMR speech coder [3GP99a] consists of the multi-