Normally all the congestion control method discard the received packet when the queue is full but it is a great problem for speed of data transfer at present. There are many ways to solve this problem. Random Early Detection (RED) algorithm is one of the most famous and powerful method to improve the performance for TCP Connection. In terms of queue management RED drops packet in considered router buffer to adjust the network traffic behavior according to the queue size. We want to investigate how high priority user datagram protocol (UDP) traffic affects the performance of lower priority Transmission Control Protocol (TCP) and proof that RED is the better for controlling the Traffic when they share the same bottleneck link with one or two classes of service.