Congestion control mechanism is one of the key that keeps any network efficient and reliable for the users. Many mechanisms were proposed in the literature over theses years for the efficient control of congestion that occur in the network. Active Queue Management (AQM) is one such mechanism which provides better control in the recent years. It works at the router for controlling the number of packets in the router's buffer by actively discarding an arriving packet. Many schemes were proposed which give better delay performance and high throughput over different traffic conditions. In this paper an exhaustive survey is made on the AQM techniques that are proposed and the merits and short falls is presented.

Active Queue Management, Congestion Control, Queue length, Link utilization, TCP, Non-TCP