A summary of each of the 7 Layers of the OSI Model

Jumai is a Network Engineer at Red Hat and she has been assigned a training session for a group of young Red Hat interns. She is writing a detailed summary of each of the 7 layers of the OSI model. what is she going to write?

For Jumai, crafting a detailed summary of each layer of the OSI (Open Systems Interconnection) model for her Red Hat interns involves not just explaining what each layer does, but also how it relates to the real-world applications and technologies they'll encounter at Red Hat. Here’s a structured approach Jumai might take to explain the 7 layers of the OSI model:

1. Physical Layer

  • Function: Transfers raw bits over a physical medium.
  • Details: Deals with the hardware connection and the transmission and reception of unstructured raw data between a device and a physical transmission medium. Includes specifications for cables, connectors, and signal specifications.
  • Real-world example: The design and maintenance of physical equipment like routers, cables, and switches.

2. Data Link Layer

  • Function: Transfers data frames between devices on the same network.
  • Details: Provides node-to-node data transfer—a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. Divided into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC).
  • Real-world example: Ethernet and Wi-Fi are protocols that work at this layer to manage how devices on a LAN access resources and communicate.

3. Network Layer

  • Function: Decides which physical path the data will take.
  • Details: Responsible for packet forwarding including routing through intermediate routers. It's where routing takes place.
  • Real-world example: Internet Protocol (IP) operates here, managing logical addressing so that any endpoint can be identified.

4. Transport Layer

  • Function: Provides reliable data transfer services to the upper layers.
  • Details: This layer manages end-to-end control and error-checking to ensure complete data transfer. It includes TCP (Transmission Control Protocol) for reliable delivery and UDP (User Datagram Protocol) for fast, but less reliable delivery.
  • Real-world example: TCP is used for applications requiring reliable communication, while UDP is used for streaming and real-time applications.

5. Session Layer

  • Function: Manages sessions between applications.
  • Details: Establishes, manages, and terminates connections between applications. It's responsible for setting up, coordinating, and terminating conversations, exchanges, and dialogs between the applications at each end.
  • Real-world example: NetBIOS and SOCKS operate at this layer, managing sessions for web services and other networked communications.

6. Presentation Layer

  • Function: Ensures that the data is in a usable format and is where data encryption occurs.
  • Details: Translates data between a networking service and an application; for example, it ensures that data sent from a network service is presented correctly to the user or application. Handles data encryption, compression, and translation.
  • Real-world example: SSL/TLS encryption protocols work at this layer to encrypt data before it's transmitted over the internet.

7. Application Layer

  • Function: Enables end-user processes and applications to access network services.
  • Details: This layer interacts with software applications that implement a communicating component. Protocols like HTTP, FTP, SMTP, and DNS work at this layer to provide end-to-end communication services for applications.
  • Real-world example: Web browsers and email software utilize protocols operating at this layer to communicate over the internet.

Jumai can use this structure to illustrate not only the theoretical aspects of the OSI model but also its practical applications, particularly focusing on how these layers facilitate the operations and services that Red Hat delivers to its customers. This approach helps interns grasp both the foundational networking principles and their relevance to their future work.

You should also read: