Transcript What is a computer network?

Unit 1
Networks Workbook
What is a computer network?
What is a
computer
network?
A network is a group of computer and other devices
connected together.
Create a list of the
activities computer
networks make
possible.
Activities
Share files and data
Share printers
Communication (email, social media etc)
Streaming content (videos, TV music)
Storing data (cloud computing)
Accessing the internet
Types of Network
Identify the network type from the description.
Type of Network Description
Example
Wide Area
Network (WAN)
Connect computers over a
large area such as a town,
city or country.
The internet (a global
computer network)
Local Area
Network (LAN)
Connect computers over a
building or a site.
School network
Personal Area
Network (PAN)
Connect computers or
devices used by one
person.
Bluetooth headset
connected to a mobile
phone
Bus Topology
Describe
the bus
topology
Single main cable to which computers are connected.
Advantages:
Easy to install and
doesn’t require much
cabling.
Bus topology diagram
Disadvantages:
If the main cable fails
the entire network will
go down.
Ring Topology
Describe
the bus
topology
All computers are connected in a circle.
Advantages:
Better performance
than bus topology.
Ring topology diagram
Disadvantages:
A failure in any cable
or device can take
down the entire
network.
Star Topology
Describe
the bus
topology
All computers have their own link to a central computer.
Advantages:
A failure in one cable
will only take down
one computer’s
network access.
Star topology diagram
Disadvantages:
Requires more cable.
Mesh Topology
Describe
the bus
topology
Where each computer can connect to other computers.
Advantages:
Even if one cable fails
there is always an
alternative.
Mesh topology diagram
Disadvantages:
High cost and difficult
setup.
Network Media
Use internet research to complete the table below:
Type
Range
Transmission Speed
Security (Good,
Medium, Poor)
Copper
Cable
Up to 500m
1000 Mbps
Medium
Fibre Optic
Up to 10,000m 100 Gbps
Cable
Good
Wireless
Poor
Up to 250m
600 Mbps
Transmission Speed
Data
transmission
speeds are
measured in:
Bits per second (bps).
Data storage is
Bits per second (bps).
measured in:
The formula
used to
calculate how
Time = size of file (bits) / network speed (bits)
long it will take
to transfer a
file:
Transmission Time
Calculate the transmission times for the following scenarios:
Scenario
Answer (including working)
File Size: 16384 bits
File Size: 2 KB
Speed: 5 Mbps
Speed: 5,000,000 bps
Time = 0.0032768
File Size: 24576 bits
File Size: 3 KB
Speed: 1 Mbps
Speed: 1,000,000 bps
Time = 0.024576
File Size: 81920 bits
File Size: 10 KB
Speed: 2 Mbps
Speed: 2,000,000 bps
Time = 0.04096
Transmission Time
Calculate the transmission times for the following scenarios:
Scenario
Answer (including working)
File Size: 8192 bits
File Size: 1 KB
Speed: 10 Mbps
Speed: 10,000,000 bps
Time = 0.0008192
File Size: 8388608 bits
File Size: 1 MB
Speed: 4 Mbps
Speed: 4,000,000 bps
Time = 2.097152
File Size: 65536 bits
File Size: 8 KB
Speed: 1 Gbps
Speed: 1,000,000,000 bps
Time = 0.000065536
Error Detection
Identify the keyword from the description.
Keyword
Checksum
Description
A checksum is an algorithm used to check for errors in data
transmission. It works by calculating a numerical value based on
the number of bits in a packed of data. This value is attached to
the packet.
When the packet reaches its destination, the same checksum
algorithm is applied to the data. If the two checksums don’t
match it shows that an error has occurred and the receiving
computer asks the sending computer to re-send that package.
Parity Checking
What is parity
checking?
Parity checking is a simple form of error detection. A parity
bit is added to the end of a string of binary code to
indicate whether the number of bits in the string with the
value 1 is even or odd. There are two type of parity bits:
What is even
parity?
Where the bit is set to 1 if the number of bits is odd. The
extra parity bit will make the number of 1s even.
What is odd
parity
Where the parity bit is set to 1 if the number of bits is even.
The extra parity bit will make the number of 1s odd.
Parity Checking
Add an even and an odd parity bit to each of these numbers.
Data being
transmitted
Even parity
Odd parity
1011010
10110100
10110101
0110111
01101111
01101110
1100000
11000000
11000001
0101111
01011110
01011111
Network Addressing
What is a MAC A MAC address is a unique number written into the network
card, composed of six pairs of hexadecimal characters.
address?
What is a
hostname?
A host name is a human-readable label that is assigned to
a network device.
Give an
example of a
MAC address
00:10:5A:44:12:B5