| Application (7) |
Closest to the user; provides network services and interfaces for applications |
HTTP, FTP, DNS, SMTP, SNMP |
| Presentation (6) |
Translates, encrypts, compresses data; ensures machine-independent data formatting |
SSL/TLS, JPEG, MPEG, ASCII, EBCDIC |
| Session (5) |
Manages sessions or connections between applications; handles authentication and synchronization |
NetBIOS, RPC, PPTP, SAP, SDP |
| Transport (4) |
Provides reliable or unreliable data transport with error recovery and flow control |
TCP, UDP, SCTP, SPX |
| Network (3) |
Handles logical addressing and routing between different networks |
IP (IPv4/IPv6), ICMP, IGMP, IPsec |
| Data Link (2) |
Ensures reliable transfer across physical link; handles MAC addressing and framing |
Ethernet, PPP, ARP, MAC, HDLC, Frame Relay |
| Physical (1) |
Transmits raw bitstreams over physical media; defines hardware specs and signal modulation |
Coaxial cable, RJ45, Fiber optics, Wi-Fi, Bluetooth, Hubs |
Techy Chalkboard in bits and pieces 