Networks: latency, throughput and layered delivery
| English | 中文 | Pinyin |
|---|---|---|
| throughput/ˈθruːpʊt/ | 吞吐量 | tūn tǔ liàng |
| latency/ˈleɪtənsi/ | 延迟 | yán chí |
What would explain this observation?
- A small message can arrive late on a high-bandwidth link. Capacity and delay measure different properties.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Packets carry addressed data through a network. A layered model separates responsibilities such as application meaning, transport delivery and network routing. Bandwidth describes capacity; throughput 吞吐量 is the achieved data rate; latency 延迟 is delay.
- throughput: Achieved rate of useful data transfer; latency: Delay experienced in communication.
Why can completion exceed file-size divided by link rate?
Transmission time depends on data size and rate. Total delay may also include propagation, processing and queueing. Encryption protects content under its assumptions but does not remove congestion or every metadata exposure.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Transmission time depends on data size and rate. Total delay may also include propagation, processing and queueing. Encryption protects content under its assumptions but does not remove congestion or every metadata exposure.
- Trace a message route using a documented local model. Record payload size, units and measured time. Use school-approved networks and synthetic messages; do not scan or intercept another user traffic.
Which two habits make the investigation or model in this case more defensible?
Trace a message route using a documented local model. Record payload size, units and measured time. Use school-approved networks and synthetic messages; do not scan or intercept another user traffic.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: an 8 megabit file crosses a 2 megabit/s link. Ideal transmission time = size/rate = 8/2 = 4 s. Protocol overhead, other users and latency can make observed completion slower.
A 12 megabit file crosses a 3 megabit/s link. Calculate ideal transmission time. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A 12 megabit file crosses a 3 megabit/s link. Calculate ideal transmission time.
The result is 4 s. Known: an 8 megabit file crosses a 2 megabit/s link. Ideal transmission time = size/rate = 8/2 = 4 s. Protocol overhead, other users and latency can make observed completion slower.
Check the conclusion and its limits
- A megabyte is eight megabits before considering overhead. A faster rated link does not guarantee low latency or secure endpoints.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
A high-bandwidth connection guarantees zero latency. This claim is false: A megabyte is eight megabits before considering overhead. A faster rated link does not guarantee low latency or secure endpoints.
Networks: latency, throughput and layered delivery: Transmission time depends on data size and rate. Total delay may also include propagation, processing and queueing. Encryption protects content under its assumptions but does not remove congestion or every metadata exposure.
A high-bandwidth connection guarantees zero latency.
A megabyte is eight megabits before considering overhead. A faster rated link does not guarantee low latency or secure endpoints.
Achieved rate of useful data transfer: write the technical term.
throughput means Achieved rate of useful data transfer.