Go-Back-N vs Selective Repeat: Which Protocol Wins the Reliability Race?
Go-Back-N and Selective Repeat are sliding-window ARQ protocols that guarantee every packet arrives correctly. Go-Back-N retransmits the lost packet plus all that follow; Selective Repeat resends only the specific packet that failed, shrinking retransmissions.
Students cramming for exams and engineers on Slack often mash the two together because both use sequence numbers and ACKs. The confusion peaks when screenshots show timers—without context, the difference seems trivial until live video drops.
Key Differences
Go-Back-N keeps one timer for the entire window; a single loss triggers bulk retransmission. Selective Repeat tracks each packet individually with its own timer, making recovery precise but demanding more memory for out-of-order storage.
Which One Should You Choose?
Streaming Netflix? Go-Back-N’s simplicity fits. Running high-frequency trading apps? Selective Repeat’s pinpoint recovery saves microseconds that equal millions. Match protocol overhead to your latency and memory budget.
Examples and Daily Life
Think of Go-Back-N as resending an entire email thread after one typo, while Selective Repeat edits only the typo line. Your Wi-Fi camera uses Go-Back-N; your smart-city traffic sensors rely on Selective Repeat to avoid jamming intersections.
Can I mix the two protocols?
Hybrid schemes exist—TCP Reno uses Go-Back-N for bulk and Selective-Repeat-like SACK for accuracy.
Do modern networks still use Go-Back-N?
Yes, lightweight IoT firmware favors its low RAM footprint over granular recovery.