OSI Layers — quick explanations
🌐
Application
User app data (message text). Interacts with user.
🎨
Presentation
Encoding/formatting (e.g., UTF-8). Prepares data for transport.
🔗
Session
Manages sessions/connections (start/stop).
📦
Transport
Adds TCP/UDP header (ports, seq). Segmentation & reliability.
🛣️
Network
Adds IP header (src/dst IP) — routing between networks.
💽
Data Link
Adds MAC header/frame for local delivery on the link.
🔌
Physical
Bits on the wire (0/1) — physical transmission.
Sender: 💻 49.20.60.12 → Receiver: 💻 49.20.60.20
💻
49.20.60.12
Ready — press Send ▶️
💻
49.20.60.20
Action: —
Short explanations and header stack appear on the right during simulation.
Encapsulation / De-Encapsulation
The stack shows how headers are added (encapsulation) and removed (de-encapsulation).
State: Idle
• Encapsulation: App → Pres → Sess → Trans → Net → DL → Phys (headers added)
• Transmission: Packet moves across the network (left → right).
• De-Encapsulation: Phys → DL → Net → Trans → Sess → Pres → App (headers removed).