🌐 OSI Explain

The Open Systems Interconnection (OSI) Model

The OSI model is a conceptual framework that standardises the functions of a communication system into seven distinct layers. Each layer serves a specific purpose and communicates with the layers directly above and below it.

Click on any layer below to access detailed explanations, protocol examples, interactive demonstrations, and teaching materials for that specific layer.

🧠 Memory Aid

Please Do Not Throw Sausage Pizza Away

Physical • Data Link • Network • Transport • Session • Presentation • Application

7
Application Layer
Network services directly to end-user applications
HTTP, HTTPS, FTP, SMTP, DNS, DHCP, Telnet, SSH
6
Presentation Layer
Data translation, encryption, compression, and formatting
SSL/TLS, JPEG, GIF, PNG, MPEG, ASCII, EBCDIC
5
Session Layer
Establishes, manages, and terminates connections between applications
SMB, NetBIOS, RPC, SQL Sessions, SSH, PPTP
4
Transport Layer
Reliable data transfer, error recovery, flow control
TCP, UDP, SPX, SCTP
3
Network Layer
Routing, logical addressing, path determination
IP, IPv6, ICMP, OSPF, BGP, RIP
2
Data Link Layer
Node-to-node delivery, error detection, MAC addressing
Ethernet, Wi-Fi, PPP, Frame Relay, STP
1
Physical Layer
Physical transmission of raw data bits over medium
Cables, Fibre Optic, Radio Waves, Bluetooth, USB