The Transmission Control Protocol (TCP), a key functional building block of the Internet, operates as a rate-adaptive end-to-end protocol at the Transport Layer of the network protocol stack. It regulates the prevailing load conditions within the network by getting the source node to adapt the packet transfer rate in accord with the processing capacity of the receiver. The regulation is enforced by means of dropping of packets on the part of the receiver. The TCP sender then reduces the packet injection rate so as to allow the network to recover from congestion. The focus of this paper is performance evaluation of certain notable TCP congestion avoidance algorithms, namely, Vegas, Reno and New Reno. Specifically, a number of performance measures have been analysed based on ns-2 simulation data where the scenarios involved TCP flows operating with identical and cross-variant congestion control mechanisms. Congestion window behaviour, packet loss, throughput, transmission delay and jitter are the performance criteria studied with the setup mentioned. In the flows with identical variants, Vegas outperforms other TCP variants. However, TCP Vegas has been observed to contribute to unfair appropriation of the resources in the cross-variant setting.
Performance evaluation of different transport layer protocols on the IEEE 802.11 and IEEE 802.15.4 MAC/PHY layers for WSN
