Index IntroductionISO Model ImageProtocolsTCP vs UDPTCP/IP vs ISO ModelIntroductionThe seven-layer OSI stands for Open Systems Interconnect reference model is a fix to the way data travels across a network, it is an international system standard for communication, the ISO reference model is divided into seven different layers, these are the application, presentation, session, transport, network, data link and physical link. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Another reason for the ISO reference is to show how a device on a network communicates with another device, the data is broken into packets because the data is too large to transmit over a network. Networks are a collection of devices connected to a server or hub. It is necessary for the signal to be converted into a digital format so that the computer can understand the information that is being transmitted, the data is transformed into binary bits. The lower three layers of the model are responsible for moving packets over the network to the device end, while the upper four layers serve to convert the data into packets and complete the communication process over the network. The model creates a diagram of the interconnection of each level and the relationships between the levels below and above the current level. Each layer is responsible for performing different functions and protocols for transmitting data over the network, these protocols are rules and procedures for switching on the network. Each layer has different protocols needed for each layer to communicate with each other. Standards are also used in the seven level model, these are rules and procedures that have been created by an organization or government body as a standard way of doing something, this is used so there are not many different ways of doing something .Image of the ISO model application layer. The application layer includes the seven layers of the ISO model, this layer is used by network applications, makes use of end-user services and processes, allows the network to verify user authentication and privacy, the level also allows file transfers, email and other network software services.[1] These processes are served by a protocol that operates at the application layer, called Hypertext Transfer Protocol (HTTP), telnet, Dynamic Host Configuration Protocol (DHCP), and File Transfer Protocol (FTP). This layer deals with email messages and files. It uses gateways to send information to the network layer. Presentation level. The presentation layer data is formatted into a representation that the network can understand, it also takes care of the encryption and decryption of the data. the presentation layer works to transform the data into the form that the application layer can accept. The data is translated from the application to the network format. This layer transforms the data so that layers below and above can understand what is being transferred and accept it. The protocols used are AES encryption, American Standard Code (ASCII), Multi-Purpose Internet Mail Extensions (MIME). The devices used on this layer are firewalls and gateways. Session level. The session layer allows two applications on different computers to open, use and close a connection, its main role is to perform name recognition and other functions, such as security, necessary to allow two applications to communicate over the network, this layer coordinates and ends conversations. the protocol used in this layer is remote procedure call (RPC),Structured Query Language (SQL) and ISO 8327. This layer used a device as a gateway. Transport level. Transport layer is where data is transported across the network which uses for protocols Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) is a communication protocol used in place of TCP, it is mainly used to establish low latency connections between applications on the Internet. This level checks the data for errors once it arrives, meaning the message is delivered error-free, in sequence, and without loss or duplication. Gateways and multiplexers are devices used on this layer. Network layer. The network layer is the Internet layer, this is the layer that contains information about the packets that will be transmitted. This layer decides which physical path the data should take based on network conditions, using routers and gateways. The protocols used in this layer are Internet Protocol (IP), Network Address Translation (NAT), Address Resolution Protocol (ARP), Internet Message Control Protocol (ICMP), Internet Protocol Security is a suite of network protocols which authenticates (IPSEC), Open Shortest Path First (OSPF). Data level. The data layer sends data frames from the network layer to the physical layer. It is responsible for controlling the signals entering and leaving the network cable. On the receiving side, the data link layer packages the raw bits from the physical layer into data frames. The layer also controls the data that moves through this layer when there is no frame buffer available. The protocols used in this layer are 802.11N, Spanning Tree Protocol (STP), Ethernet, Layer 2 Tunneling Protocol (L2TP), Carrier Sense Multiple Access with Collision Detection (CSMA/CD). The protocol tells the network how to handle a device that tries to connect to the same data channel and how the device should wait to reconnect to the channel, to reduce the possibility of collision in the network, Digital Subscriber Line (DSL) and Internet Protocol Security is a suite of network protocols that authenticates (IPEC). The physical layer. The physical layer is the bottom layer of the OSI bag that transmits the raw unstructured data (signal state represents 1 or 0) on the similar physical medium. The physical layer is hardware-based and deals with all aspects of creating and maintaining a physical link between communicating computers. This layer uses different types of cables EG wire, fiber and wireless connection, the transmission speed is dampened by the type of cables used and the speed of the area. The main protocols used on the physical layer are Fast Ethernet, Carrier Sense Multiple Access with Collision Detection (CSMA/CD), and Asynchronous Transfer Mode (ATM). The ProtocolsThis image shows how each layer of the ISO model is used and the different protocols and standards used on the layers. Some of the protocols used in the ISO model are used more than once. Protocols operate at different levels of the OSI model. Each level has its own protocols. TCP and IP are collectively called protocol stacks or network/transport protocols. This is due to the protocols that operate at the Network and Transport layers to allow computers to communicate. A protocol stack, r stack, is a group of protocols arranged in layers to enable communication. In the protocol stack, each layer provides services to the layer above it; and each layer also receives services from the layer below it. In order for two computers to participate in communications, each of them must run the same protocol stack. They can, however, have operating systems.