In this article we will discuss Transport Layer Reliability, will make brief discussion on Transport Layer. In last article we discuss about Conversation Multiplexing.
Transport Layer Reliability
The transport layer is also responsible for managing reliability requirements of a conversation. Different applications have different transport reliability requirements. transport layer is the layer in the open system interconnection (OSI) model responsible for end-to-end communication over a network. It provides logical communication between application processes running on different hosts within a layered architecture of protocols and other network components.
IP is concerned only with the structure, addressing, and routing of packets. IP does not specify how the delivery or transportation of the packets takes place. The User Datagram Protocol (UDP) is simplest Transport Layer communication protocol available of the TCP/IP protocol suite. It involves minimum amount of communication mechanism. UDP is said to be an unreliable transport protocol but it uses IP services which provides best effort delivery mechanism.
Transport protocols specify how to transfer messages between hosts. TCP/IP provides two transport layer protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), as shown in the figure. IP uses these transport protocols to enable hosts to communicate and transfer data.
The transmission control protocol (TCP) is used for applications in which reliable connections between hosts are necessary. TCP is considered a reliable, full-featured transport layer protocol, which ensures that all of the data arrives at the destination. However, this requires additional fields in the TCP header which increases the size of the packet and also increases delay. In contrast, UDP is a simpler transport layer protocol that does not provide for reliability. It therefore has fewer fields and is faster than TCP.