Engineering / advanced
Transport under loss and congestion
Understand reliable delivery, congestion feedback, pacing, and transport measurements using assumptions about loss and round-trip delay.
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Module 01 advanced
Transport under loss and congestion
Understand reliable delivery, congestion feedback, pacing, and transport measurements using assumptions about loss and round-trip delay.
- 01
TCP sequence numbers describe bytes, not messages
Reconstruct byte ranges, cumulative acknowledgments, duplicate delivery, and sequence-number wrap without confusing transport receipt with application success.
23 min - 02
Sliding windows separate receiver space from path capacity
Calculate usable send credit from outstanding bytes, congestion limits, and receiver advertisements while interpreting zero-window stalls.
24 min - 03
Loss detection is an inference from incomplete evidence
Compute an illustrative TCP retransmission estimate, handle retransmitted-sample ambiguity, and distinguish duplicate-ACK recovery from timer expiry and QUIC probes.
25 min - 04
AIMD is a feedback model with a stated operating regime
Relate congestion windows, acknowledgment clocks, additive growth, multiplicative reduction, and recovery behavior without assuming every transport uses Reno.
24 min - 05
Bandwidth-delay product is the amount needed in flight
Calculate path-filling flight size, interpret window ceilings, and distinguish propagation inventory from queued excess data and short-transfer startup.
23 min - 06
Pacing controls timing while queues determine waiting
Calculate serialization and queue delay, distinguish pacing from rate limits, and evaluate active queue management without assuming large buffers solve overload.
24 min - 07
Selective acknowledgments describe islands beyond a gap
Interpret SACK blocks as half-open received ranges, maintain a recovery scoreboard, and distinguish selective evidence from cumulative acknowledgment and durable receipt.
24 min - 08
QUIC separates stream positions from connection paths
Distinguish stream offsets, packet numbers, connection IDs, path validation, and anti-amplification limits when reasoning about reliable delivery across address changes.
26 min - 09
Head-of-line blocking depends on which ordering contract applies
Trace blocking through TCP bytes, HTTP multiplexing, QUIC streams, compression dependencies, and application scheduling before choosing a transport architecture.
25 min - 10
Diagnose the binding transport constraint before tuning
Build a falsifiable diagnosis from useful throughput, flight size, RTT inflation, receive credit, recovery events, host limits, and controlled workload comparisons.
27 min