A computer network consists of many parts and the most up-to-date method for conceptualizing computer networks is the so-called Open Systems Interconnection (OSI) seven-layer model. For network technicians, the OSI seven-layer model provides a practical tool for diagnosing network problems and a common language for networking.
first Layer – Physical: Includes cables for transmitting data between computer systems. CAT 5E or CAT6 rated unshielded twisted pair (UTP) is common in most networks. The optical cable that uses wave waves to transfer data packets to electrical waves has significant speed and distance benefits at UTP, but there is no durability. In the OSI Model Layer 1, as well as airborne radio waves (WAP), there are hubs that operate in the same way as the old telephone exchanges that transmit interconnected systems.
2nd Layer: Data Connection: Includes Network Interface Card (NIC), which is the interface between the computer and the network. The network card is usually integrated into the motherboard and has a Media Access Control (MAC) address assigned to each network with a unique identifier. The MAC address is used to ensure that data is transferred to the appropriate computer and the network cards use electricity to transmit and receive binary data packets in the form of electrical, light signal or radio waves
3. Layer: Network: Use logical addressing using a so-called protocol that effectively moves data packets along the physical and data link layers of the OSI model. The most common protocol is TCP / IP, which in collaboration with routers in Layer 3 ensures that data is sent and received in the desired computer system. Other protocols that use logical addressing such as POP and SMTP Emails are also located in the network layer
4. Layer: Delivery: Includes a protocol designed specifically for assembling and disassembling data packets. The data must be sent in packages that correspond to the specific packet sizes, and then the data read in the receiving computer system are re-assembled. The transport layer network protocol breaks down the data and assigns serial numbers that allow host systems to process the data.
5th Layer: Session: Contains a protocol that initiates data sessions between computer systems, accepts incoming sessions, opens and closes existing sessions. The network layer protocol of the session layer also monitors the computer naming convention to facilitate data transfer processes between computer systems.
6th Layer: Presentation: Includes software that converts the data into standardized file formats that allow computers to receive and convert data to a computer system that is readable. PDF and Adobe Acrobat are examples of a standardized file format software that allows computer systems to convert data into readable files
7. Layer: Application: Includes software applications that allow users to access and use data files. Web browsers, such as Internet Explorer and Mozilla Firefox, and e-mail programs, such as Outlook Express, can be found in the Application layer. Layer 7 also includes code built into operating systems that allow network monitoring applications and application programming interfaces (APIs).
Please do not drop the sweet potato: Useful reminder to memorize the seven layers of the OSI Seven Layer Networking Model.
Source by sbobet