Priority Checking RED for Improving QoS in IPv6

This paper presents a priority checking random early detection (PC-RED) gateway for ensuring the quality of service (QoS) of high priority dataflow in IPv6 networks. A bit in the IP header is used in PC-RED to label the packet with the current status of the QoS that the dataflow is being treated in. The status of the QoS is determined by the difference between the packet average-dropping rate and the fixed desired limit dropping rate of the dataflow. PC-RED would perform dissimilarly to every dataflow corresponding to the different QoS status throughout congestions. PC-RED has been modeled and the parameter setting has been studied. Simulations of a TCP/IP network are used to illustrate how PC-RED affects the transfer of dataflow. The result shows remarkable contrast between the high-priority and non-priority dataflow throughput under PC- RED mechanism.