Discussion: OSI Layer 7 OSI 7 Layer Model OSI is a network architectural model developed by the Agency for International Organization Of standardzation (ISO) in the territory of Europe in 1977. OSI stands for Open Systems Interconnection.

OSI reference model (Open Systems Interconnection) illustrates how information from a software application on a computer is moved across a network medium to a software application in another computer. OSI reference model is conceptually divided into seven layers where each layer has a specific network functions. Model Open Systems Interconnection (OSI) created by the International Organization for Standardization (ISO), which provides a structured framework of the logic of how the process of interacting data communication over a network. Standards were developed for the computer industry so that the computer can communicate on different networks efficiently. There are seven layers of the OSI model. Each layer is responsible for a particular aspect of data communication. For example, one layer is responsible for establishing connections between devices, while another layer is responsible for correcting the "error" during data transfer.

OSI Layer Model divided into two groups: the "upper layer" and "lower layer". "Upper layer" focus on user applications and how files are represented on the computer. For Network Engineer, major part of which became the focus is on the "lower layer". Lower layer is the essence of real-time data communication over a network.

The main purpose of use of the OSI model is to help network designers understand the function of each layer associated with the flow of data communication. Including the types of network protocols and transmission methods.

Explanation 7 Layer Model (Seven Layer Model)

Application Layer: The layer all 7 describes the specifications for the scope in which to communicate with his network application network services. Provides services to user applications. It is responsible for the exchange of information between computer programs, such as e-mail programs, and other services running on the network, such as a printer server or other computer applications. Serves as an interface to applications with network functionality, manage how applications can access the network, and then create error messages. Protocols that are in this layer are HTTP, FTP, SMTP, DNS, TELNET, NFS and POP3. Presentation Layer: The layer all 6 serves to translate the data to be transmitted by the application into a format that can be transmitted over the network. Protocols that are in this level is software redirektor (redirector software), such as the Workstation service (in Windows NT) and Network shell (such as Virtual Network Computing (VNC) or Remote Desktop Protocol (RDP)). Session layer: This layer is the 5th serves to define how connections can be created, maintained, or destroyed. In addition, at this level also carried the name resolution. Protocols that are in this layer is RPC (Remote Procedure Call), and DSP (AppleTalk Data Stream Protocol). Transport layer: This layer is the 4th serves to break down the data into packets of data and provide the serial number of all packets so that they can be rearranged on the side of the goal after receipt. In addition, at this level also makes a sign that the packet is received successfully (acknowledgment), and terhadp retransmit lost packets in the middle of the road. Protocols that are in this layer is UDP, TCP, and SPX (Sequence Packet Exchange). Network layer: 3rd layer serves to define the IP addresses, create the header for the packets, and then perform routing through internetworking using routers and layer-3 switches. Protocols that are in this layer is DDP (Datagram Delivery Protocol), Net BEUI, ARP, and RARP (Reverse ARP). Data-link layer: Layer-2 functions to determine how the data bits are grouped into a format called a frame. In addition, at this level of error correction, flow control, addressing hardware

(such as the Media Access Control address (MAC address)), and determine how the network devices such as hubs, bridges, repeaters, and a layer 2 switch operates. IEEE 802 specification, this level divides into two child level, the layer Logical Link Control (LLC) and Media Access Control layer (MAC). Physical Layer: The layer-1 serves to define the network transmission medium, signaling methods, bit synchronization, network architecture (such as Ethernet or Token Ring), network topology and cabling. In addition, this level also defines how the Network Interface Card (NIC) can interact with the media cable or radio. Protocols that are in this layer is Ethernet, FDDI (Fiber Distributed Data Interface), ISDI, and ATM.