Transport Layer In Tcp Ip example essay topic

TCP / IP reference model contains two primary protocol TCP (Transmission Control Protocol) and IP (Internet Protocol). TCP / IP model is based on four layers. TCP / IP model is itself not much used but its protocol is widely used. It does not contains some features found under the OSI model.

The description of four layers of TCP / IP model are as follows. Layer 1 - HOST-TO-NETWORK: It contains both physical and data link layers of the OSI model. Actually the TCP / IP does not say much about this layer. The only purpose of this layer is to allow host to connect to the network using some protocol so that it can send IP packets.

Layer 2 - INTERNET: This layer is the key of the architecture. This layer is used for basic communication, addressing and routing. Its role is to deliver packets where it supposed to go. The packet may reach or may not reach to the destination.

There are many other function at this layer. TCP / IP uses IP and ICMP protocols at the network layer. Layer 3 - TRANSPORT: It has the same role as the transport layer of the OSI model. The two main function provided by this layer is flow control (how much data is transmitted) and reliability (mechanism of delivery of each packet). It also segments and reassembles data streams for application layer. TCP and UDP falls in this layer.

Layer 4 - APPLICATION: TCP / IP model does not contain session and presentation layers because network software hardly use these layers. End-user applications are present at this layer. This layer holds all high level protocols such as TFTP, FTP, NFS, SMTP, TELNET, RLOGIN, SNMP, DNS etc. COMPARISON OF TCP / IP AND OSI MODEL: The OSI and TCP / IP model have many things in common but there is some difference between them.

OSI reference model was developed first then its protocol was developed. For TCPIP protocol was developed first then model was developed. The application layer of the TCP / IP handles the responsibilities of layers 5, 6, and 7 in the OSI model. OSI reference model is general i.e. it is not developed for a specific set of protocol, if there is new development we can fit it in this model. TCP / IP model is specific i.e. it is not useful for describing other non TCP / IP networks. The OSI model makes clear distinction between 3 main concepts.

TCP / IP does not make clear distinction between these concepts. These 3 concepts are services, interfaces and protocol. The service tells what the layer does. The interface tells the processes above it how to access it. The protocol tells the standard made for communication.

Connection-oriented modes and connectionless modes are available in both OSI and TCP / IP models. But they are not available at the same layer. In the OSI model, these modes are only available at the network layer, but at the transport layer it has only the connection-oriented mode. While In the TCP / IP model the internet layer only offers the connectionless mode but supports both modes in the transport layer.

Therefore, the TCP / IP has an advantage, compared to the OSI model i.e. applications that directly use the transport layer) have the choice between both modes or the transport layer in TCP / IP does not guarantee reliable delivery of packets as the transport layer in the OSI model does..