Worksheet

F10.3 Network performance

Networks · GCSE · OCR J277 1.3.1, Edexcel 1CP2 4.1.5 · about 15 min

What this lesson is about

Bandwidth, transfer time calculations, what slows a network, and measuring latency with a ping.

• Speed and bandwidth
• Calculating transfer time
• What slows a network down?
• Measuring latency

Questions 5 marks in all

1. [1 mark]How many seconds does a 25 MB file take to send at 10 Mbps?

2. [1 mark]What is bandwidth?

   1. AThe most data a connection can carry each second
   2. BThe length of a cable
   3. CThe number of devices on a network
   4. DThe delay before data arrives

3. [1 mark]Why is a home internet connection often slower in the evening?

   1. AMore users are sharing the bandwidth
   2. BCables cool down at night
   3. CRouters switch off at night
   4. DServers run slower in the dark

4. [1 mark]What is latency?

   1. AThe delay for data to travel from one device to another
   2. BThe total amount of data sent
   3. CThe number of packets lost
   4. DThe speed of the processor

5. [1 mark]How many megabytes per second is a 100 Mbps connection?

The task: ping the server

Ping the Server three times. For each ping, send ping, time how long until a reply arrives using clock(), and print ping <n>: <seconds> s, rounded to two decimal places. Then print average: <seconds> s, also rounded to two decimal places.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

Plan your program here, then type it in and press Run.

Do it on the robot
www.bugbotlab.com/learn/f10-3-network-performance/
The simulator checks it and tells you when it passes. Nothing to install, no account.

Challenges

1. How long does a 2 GB file take over a 50 Mbps connection? Over 1 Gbps?
2. Ten people share a 100 Mbps connection equally. How long does each take to download a 250 MB update?
3. Why does latency matter more for an online game than for downloading a film?