Separate latency, throughput and loss by measurement

short · 50 min · Objective 6.2

Task

Introduce each of the three network impairments independently and measure how they differ, then show the relationship that confuses people: high latency limits throughput even when bandwidth is plentiful.

Steps

  1. Measure the baseline between the two hosts with a TCP-based tool: round-trip time, single-stream throughput, multi-stream throughput and loss. Record in lab/net/impair.csv.
  2. Add 100 ms of latency only -- no loss, no bandwidth limit. Re-measure all four and record. Note what happened to single-stream throughput despite the link being unchanged.
  3. Remove the latency and add 1% packet loss only. Re-measure and record the effect on throughput.
  4. Remove the loss and impose a hard bandwidth cap. Re-measure and record how this looks different from the first two.
  5. With the 100 ms latency restored, compare single-stream against eight-stream throughput and write in lab/net/impair.md why parallel streams helped and why a bigger link would not have.

Verify

awk -F, 'NR>1 && NF>=4 {n++} END {print n" measurement set(s)"}' lab/net/impair.csv
grep -Eci 'window' lab/net/impair.md
grep -Eci 'parallel|multi.stream' lab/net/impair.md
grep -Eci 'loss' lab/net/impair.md

Four measurement sets, and the notes must explain the window/RTT relationship. A small amount of loss should hurt throughput out of proportion to its size -- if it did not, the transfer was too short to trigger congestion control.

This is an independent study companion for CompTIA Cloud+ CV0-004 and is not produced by or endorsed by CompTIA.