星期三, 10月 29, 2025

Computer Network

How Networks Handle Packet Loss: TCP vs. UDP TCP: The Reliable Method (e.g., File Transfer, Web Browsing) Sender Receiver Time 1. Sender sends numbered packets P1 P2 2. Packet 3 is lost in transit! P3 P4 3. Receiver ACKs what it got (P1, P2) ...and keeps requesting P3 by sending ACKs for P2 ACK 1 ACK 2 ACK 2 (Dup ACK) 4. Sender retransmits the lost packet P3 5. Data is complete and ordered. Transfer resumes. ACK 4 UDP: The Fast Method (e.g., Video Streaming, Online Gaming) Sender Receiver Time 1. Sender streams packets continuously F1 F2 F3 2. Frame 4 is lost. No retransmission occurs. F4 F5 3. The stream continues, causing a minor glitch. Speed is prioritized over perfection. Frame 2 Frame 3 Glitch Frame 5 4. User experiences a brief imperfection, not a pause.

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