Protocols and Layers

Question 1

What is Ethernet?

Answer 1

Ethernet is a family of standards that covers

The physical design of plugs, sockets and cables
How devices will start, stop and handle data exchange
How to handle network errors

Question 2

What Ethernet standards does Ethernet cover?

Answer 2

In any network, the plugs must fit into the sockets; the cable must behave the same way no matter who you buy it from. You should be able to purchase network cards from one supplier and know that they will work with cards from another supplier.

Question 3

How is data sent across the network?

Answer 3

Most networks break up the data they want to exchange into separate chunks called a packet. Each type of network formats its packets differently, adding or removing certain bits of extra information. For example, packets sent over the Internet will have IP-address information.

Question 4

What is the format called in a Ethernet network?

Answer 4

In Ethernet networks, the format for a packet is called a ‘frame’.

Question 5

What do frames include?

Answer 5

Frames include:

• The data being sent
• The MAC address of the device sending the packet
• The MAC address of the device receiving the packet
• Error checking bits

Question 6

What do the ‘‘error checking bits’’ do?

Answer 6

The error checking bits are, as their name suggests, checked by the receiving computer device to ensure the packet arrived intact. If it finds an error, the device either sends back a request to re-send that packet or it discards the packet.

Question 7

How is data taken in turns in an Ethernet network?

Answer 7

Ethernet describes how devices must take turns to send their data.

This helps avoid two devices trying to send their data through a cable at exactly the same time which results in a ‘data collision’

Question 8

What are the rules to sending data in a ethernet

Answer 8

The Ethernet rules are

• Check that the cable is unused before sending out a data packet
• If two packets do collide then each device must wait a short random time before re-sending their packet. This lessens the chances of it happening again.

The network term for this taking-turns process is called ‘handshaking’.

Question 9

What are the two types of wireless network?

Answer 9

• Bluetooth
• Wi-Fi

Question 10

What is bluetooth?

Answer 10

Bluetooth is a type of radio communication and networking protocol combined.

Question 11

Why was Bluetooth developed how does it make it ideal?

Answer 11

It was developed so devices close to one another could exchange data, without any need for a physical connection and yet use very little power. Making it ideal for mobile and portable devices.

Question 12

What is the range of Bluetooth?

Answer 12

By close, we mean within about 10 metres of one another even if there is a wall in-between.

Question 13

What is Bluetooth popular for?

Answer 13

This method of network connection is popular with:

• Smart-phone to car entertainment systems
• Blue tooth enabled speakers and headphones
• Downloading from digital cameras.
• Connecting to blue-tooth enabled printers.

Question 14

What is Bluetooth bandwidth?

Answer 14

Low bandwidth compared to Wi-Fi

Question 15

What is Wi-Fi?

Answer 15

Wi-Fi is a communication technology that makes use of radio waves in order to connect to a local area network.

Question 16

What is Wi-Fi widely used for?

Answer 16

It is also widely used to connect to the internet from a laptop or smart phone whilst out and about.

Question 17

What devices have Wi-Fi built in?

Answer 17

All laptops have Wi-Fi built in.

Question 18

What key device is needed to connect to the Wi-Fi?

Answer 18

The key device is the Wireless Access Point or WAP that handles all the data exchange. The WAP is hard-wired to the local area network or is built into a home hub to allow local Wi-Fi.

To connect, devices need a wireless NIC which is often built in if not you can use a USB dongle. HDMI dongles are popular for TVs

Question 19

What is used to help avoid data from being accessed?

Answer 19

Encryption is used to help avoid data being accessed without the right password.

Question 20

What are the issues of Wi-Fi?

Answer 20

1. Security
   Wi-Fi broadcasts your network data over radio waves and these are easily picked up by other devices within range.

Early Wi-Fi networks were open to virtually anyone. Some people made a hobby of driving around looking for open networks. But now most private networks are password enabled so it is harder for someone to break into the network.

2. Limited connections
   Just like a normal radio, Wi-Fi uses a small number of radio channels to work.

This is no problem at home where only a few connections are needed. But in a busy office, this lack of channels may mean difficulty in making a connection.

3. Limited range
   Wi-Fi is a radio technology and so it is affected by things such as walls getting in the way. For example, at home the router might be downstairs and so the signal upstairs may be very weak. This can be overcome by using a ‘wi-fi extender’ located somewhere in-between. It acts like a bridge, such as the extender shown in the picture which was plugged in a kitchen.

Question 21

What