All About The Open Systems Interconnection (OSI) Model

The OSI or Open Systems Interconnection model describes a networking framework for implementing protocols in specific layers, with control passing from one layer to another layer. This is one of the most crucial networking concepts you need to brush up on when taking the CompTIA Network+ N10 007 certification exam. The OSI model makes use of seven layers for describing what’s happening with a specific networking system. Higher layers include data representation, network requests and responses, as well as network protocols seen from the view of end users, while lower layers involve binary data chunks, electrical signals, and data routing across networks.

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These seven OSI model layers or levels include the following:

  • 7: The Application Layer – Being the highest layer of all OSI layers; it’s the layer that interacts with end users such as you or a computer programmer. It enables the access to network services.
  • 6: The Presentation Layer – The presentation layer is where data operates with the operating system. Primarily, this layer is involved in translating, encrypting, and compressing data.
  • 5: The Session Layer – The main task of this layer is to maintain proper communication through the establishment, management, and termination of sessions between computer systems. For instance, when clicking on a site, your system needs to forge a session with that site’s web server.
  • 4: The Transport Layer – The task of this layer is vital since it’s responsible for deciding the amount of information that must be transferred. For instance, when you communicate with a site, this layer would decide the amount of data you could send and receive. This layer likewise gives dependable process-to-process error recovery and message delivery.
  • 3: The Network Layer – This layer’s primary task is moving packets from the source to their destination and offering internetworking. It’s where routers operate on. For instance, while you’re aware that your New Orleans computer needs to connect to a San Francisco server, there are millions of paths that the connection could take. Fortunately, routers function to ensure accurate connection in this layer.
  • 2: The Data Link Layer – The data link layer is tasked to ensure hop-to-hop delivery and arrange bits into frames. This is where switches operate on. This layer also includes two sub-layers, which is the LLC or logical link control layer and the MAC or media access control layer.
  • 1: The Physical Layer – This layer is where real data transmission takes place. As its name implies, this covers the physical stuff such as standard network devices like repeaters and hubs, responsible for connecting computer systems together. The physical layer is where data is transmitted by utilizing a kind of signaling that the physical medium supports. These include ordinary light, infrared pulses, radio frequencies, and electric voltages.

Main takeaway—the OSI model is utilized for tracing or modeling the actual data transfer in networks. Essentially, it’s a logical representation or model of how network systems should transfer and receive data, as well as communicate with each other. By understanding how the seven layers of the OSI model function, you could likewise better understand what types of devices and protocols are interoperable.

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