The paper deals with topic of unilateral implementations of the TCP protocol in networks which has been elaborated thoroughly afterwards. Majority of the work is based on networks with implemented TCP protocol and the emersion of congestion on them, that is consideration of suppressing the congestion in due time before it has occurred by using the similar methods. After the congestion, because of certain influences, imminently occurred in the network comes to applying certain methods/protocols to eliminate the congestion. The reason of that is to find more efficient and quicker way out of congestion and to restore the balance in the network. Techniques that are used in congestion control protocols, to successfully implement and improve variations of TCP protocol, are: Slow Start, Congestion Avoidance, Fast Retransmit and Fast Recovery. The TCP, which is basically connection-oriented protocol and the protocol which is based on the most important task of packet delivery, is defined by a certain quality of service QoS which must be supported by the standards: sufficient bandwidth, the latency control, controlling the variation in jitter and decreased rate in data loss. At the end of the paper, significant improvements in the performance of TCP connection were presented. That is, modification in the network parameters that directly influence on the functioning of the protocol, considering the resources available in the network.