7 layers of the OSI model (in under 5 minutes)

7 layers of the OSI model

Always wondered what the 7 layers of the OSI model are when you're "I. T techy" friends have their technical conversations? I write this for your convenience and hopefully if you do ever find yourself in another conversation like that, you'll be excited to get stuck in that conversation. 

Layer 7. The application layer

On the application layer it is mainly concerned with human interaction and implementation of software and related protocols i.e Imap and POP3. When users communicate with the computer or cellphone and also defines processes for user authentication. Just imagine you have a meeting from your "at home" workspace and you ready to log into zoom all these data is happening on the application layer.

Layer 6. The presentation layer

The presentation layer presents the information in a proper format, encryption & compression can be found in this layer. Let's just say I zip a file for the South African POPIA act to send to a customer his latest account statement, but his details are encrypted to his identity credentials.

Layer 5. The session layer

The session layer is responsible for establishing, managing and terminating connections between applications at each end of the communication between 2 hosts. For example, someone calls you on WhatsApp but you can't hear them.

Layer 4. The transport layer

The transport layer only cares about how data is transported from computer to computer.  Segments are used to identify this data. Handles transport functions such as reliable and unreliable delivery of data to the destination. TCP lives here and is the reliable way of data being transported. UDP lives here its a protocol which send data in an unreliable way. 

Layer 3. The network layer

On the network layer it is concerned about I. P addresses and routing. Having a source and destination I. P address i.e where the information comes from and where the information is going and is referred to as packets. 

Layer 2. The data-link layer

On the data link layer data is formatted the correct way, takes care of error detection and makes sure data is delivered. Let's just say one p.c wants to communicate with another, and the switch picks it up the switch will send it back to its destination for it to be corrected before sending to its proper destination again. These data are called frames and is also only concerned with MAC addresses. 

Layer 1. The physical layer

The physical layer transports electrical or optical signals used for communication. Concerned with the physical characteristics of electrical or optical signaling techniques which include the voltage of the electrical current used to transport the signal, the media type (twisted pair cable, coaxial cable, fiber optic). Looks at the type of media and connected them thru 1's and 0's binary.

Below we can see the OSI illustration and what protocols are being used within them: