The transport layer protocols provide connection oriented sessions and reliable data delivery services. This paper seeks to reflect a comparative analysis between the two transport layer protocols, which are TCP/IP and UDP/IP, as well to observe the effect of using these two protocols in a client server network. The similarities and differences between TCP and UDP (User Datagram Protocol) over the Internet are also presented in this paper. They implement a network structure using OPNET modeler and finally, based on the practical results obtained they present the conclusions-showing the difference between these two protocols and how they work.