OSI Flashcards
Layer 1 OSI Model
The physical layer. Conveys the bitstream across the network.
Layer 2 OSI Model
The data link layer. Puts packets (the web request) into network frames and sends them to the default gateway. Ethernet.
Layer 3 OSI Model
Network layer. IP layer. Handles addressing and routing the data.
ARP - Address Resolution Protocol
IP uses ARP to figure out the physical MAC address of the default gateway
OSI
Open Systems Interconnection. Reference model for how applications communicate over a network.
Layer 4 OSI Model
Transport layer. Manages the packetization of data, delivery of the packets, and checking for error once the data arrives.
TCP connection. Breaks up the web page into manageable chunks, assigns an ordering to the chunks so they can be reassembled, then transports the pieces across the correct session.
Layer 5 OSI Model
Session Layer. Sets up, coordinates, and terminates connections. Handles authentication and reconnects.
Individual TCP connection. Web server sends back the requested webpage then closes the connection. Additional connections are opened to download the data contained in the web page such as style sheets, images, and videos.
Layer 6 OSI Model
The presentation layer. Converts data from one format to another.
Web browser and HTTP. Converts text, video, audio, and image data from one format to another.
Layer 7 OSI Model
Application layer. Not the application itself. A set of services that an application can make use of. The layer at which communication partners are identified and network capacity is assessed.
Web browser. The web browser uses network application services such as locating and contacting a web server and requesting files for that web page then displaying them.
