There are two fundamental protocols in the transport layer 1. TCP Transmission Control Protocol-- connection-oriented protocol 2. UDP User Datagram Protocol -- connectionless protocol Connection-oriented communication : establishes a logical (virtual) connection prior to sending data. Connectionless communication : sends data right away without establishing a logical connection Qn why do we have transport layer protocal? IP provides a weak, but efficient service model (best-effort ) How should hosts send into the network? i.)Flow Control ii.) Too fast is bad; too slow is not efficient IP packets are addressed to a host How to decide which application gets which packets? NOTE TRASPORT LAYER IS RESPONSIBLE FOR PROCESS TO PROCESS DELIVERY PORTS port is a communication endpoints Since there are many applications running on a computer, there is a need to decide which application gets which packet. A port number is a way to identify a specific application (proc
Introduction to layered models When networks first came into being, computers could typically communicate only with computers from the same manufacturer. For example, companies ran either a complete DECnet solution or an IBM solution—not both together. Layering is a modern network design principle that divides the communication tasks into a number of smaller parts, each part accomplishing a particular sub-task and interacting with the other parts in a small number of well-defined ways. To reduce their design complexity, most networks are organized as a stack of layers or levels, each one built upon the one below it. What differs from one network to another:- 1.The number of layers 2.The name of each layer 3.The contents of each layer and 4.The function of each layer. ->The entities comprising the corresponding layers on different machines are called peers. ->The peers may be processes, hardware devices, or even human beings. ->In other words, it is the peers that communicate