TFRC for Congestion Control in Real Time Applications

Abstract: The amount of traffic generated by Real Time Applications (RTA) has increased substantially over the years. RTA will face congestion while there's any form of bottleneck restricting traffic, this can lead to packet loss or delayed traffic that is unacceptable for RTAs. Therefore it is desirable for RTA to implement congestion control mechanism to improve the steadiness of networks. The congestion problem has been addressed successfully by Transmission Control Protocol (TCP). TCP is connection oriented protocol that presents reliable and ordered delivery of packets and also presents end-to-end congestion control mechanism. But its congestion control mechanism does not suit the characteristics of the RTA. User Datagram Protocol (UDP) applications can send data at constant bit rate. It is non TCP based protocol. It cannot adjust its flow rate when congestion is detected and it continues to send at original rate. So these non TCP applications don't have congestion control mechanism and don't share bandwidth fairly with TCP based applications. A new congestion control protocol for datagram transport was defined i.e., TCP Friendly Rate Control (TFRC) standardized by Internet Engineering Task Force (IETF). TFRC is a congestion control algorithm that supplies a smooth transmission rate for RTAs. TFRC is a congestion control mechanism for unicast flows functioning in a best effort Internet environment. It's reasonably fair when competing for bandwidth with TCP flows in congested network, although encompasses a lot of lower variation of throughput over time compared with TCP.