Vol. 2, Issue 2, Part H (2016)

Abstract
Congestion control scheme is key algorithms used to regulate the load in modern packet networks. The Stream Control Transmission Protocol (SCTP) inherited these algorithms from the Transmission Control Protocol (TCP). This paper is related to SCTP congestion control mechanisms, specifically in the Congestion Avoidance algorithm. In the congestion avoidance algorithm, the size of the congestion window increases additively until congestion is detected. However, this increase may lead to enter fast retransmit congestion control algorithm and fast recovery algorithm. For this reason we propose a new enhancement to the Congestion Avoidance algorithm by adjusting the congestion window size based on available network capacity, that can reduce congestion window rather than slow start threshold, then the cwnd is fully utilized and immediately triggers slow-start phase work again, also the SCTP sender has no wait- for-long time to receive the acknowledging and all available resources can utilize data sender rate Efficiently, by using tools of OMNet++ simulation and finally will compare the performance of the SCTP congestion control, between the proposed method and original method.