Network+ Deep Dive: Where Firewalls, Load Balancers, and APs Fit in the OSI Model
OSI Model or Open Systems Interconnect model: It is important to remember that this is a theoretical framework, meaning that it is just one way of thinking about networking. What happens at each layer? The table below shows examples of what exists at each layer, mainly hardware at the physical layer and protocols on the other layers. OSI Layers Which Headers Can Be Added at this Layer What happens on these layers Application SMTP, HTTP, FTP, HTTPS, P2P, DNS, etc. Header is added to the data (whether it is an HTTP header, SMTP, etc.) Presentation Handles data formatting, encryption, and compression to ensure data is in a usable format for the application layer. Session Managing and controlling connections between devices, including establishing, maintaining, and terminating sessions. Transport TCP, UDP, etc. ...