Networks - Protocols and OSI7

Question 1

What are protocols?

Why are they standard?

Answer 1

An agreed set of rules for communication between two computers. They are standard so that all devices have a designated method of communicating with each other, regardless of manufacturer.

Question 2

When are protocols agreed?

Answer 2

During the handshake period.

Question 3

What do the logical components of protocols tend to consist of?

Answer 3

• The types of error checking used (parity/check digit)

- Bit rate

Question 4

What do the physical components of protocols do?

Answer 4

They govern how data is transmitted

• Wire type
• WiFi frequency
• Modulation used / Type of routing

Question 5

What is the network protocol used on the internet?

Answer 5

TCP/IP

Question 6

What is a layer?

Answer 6

A group of protocols organised by function.

Question 7

Why do we use a layer model?

Answer 7

To conceptualise a complex system such as network communication.

Question 8

Why is the layer model useful for manufacturers?

Answer 8

When they are developing new hardware they can ensure it is compatible with existing protocols.

Question 9

What are the benefits of using a layer model?

Answer 9

We can map how protocols relate and interact with one another
You can tell what a protocol does by knowing which layer it resides within

Question 10

What is the OSI 7 layer model?

Answer 10

A reference model for how messages should be transmitted between any two points in a telecommunication network.

Question 11

OSI: What is the application layer?

Answer 11

The seventh layer.
It interacts with apps for communication purposes.
It determines sufficient resources available.
It controls the communication between apps
EG: Web browser.

Question 12

OSI: What is the presentation layer?

Answer 12

The sixth layer.
It organises data into a format that can be used by humans.
ASCII - Plain text for web pages
DOC - Word documents

Question 13

OSI: What is the session layer?

Answer 13

The fifth layer.

It allows you to have multiple browsers and resources open simultaneously without data conflicts in transmission.

Question 14

OSI: What is the transport layer?

Answer 14

The fourth layer.
Responsible for
- Flow control
- Multiplexing
- Packeting
- Error checking and recovery
Firewalls operate at this level.

Question 15

OSI: What is the network layer?

Answer 15

The third layer.
Logical address for a server or workstation is managed here. Common protocol is TCP/IP
Routing takes place at this level

Question 16

OSI: What is the data link layer?

Answer 16

The second layer.
Data bits organised into frame structure.
- Beginning and end of data frame
- Sender address
- Receiver address
- Error checking of data frame

Question 17

OSI: What is the physical layer?

Answer 17

The first layer.
It transmits and receives data bits as electrical pulses.
It controls physical link between communicating systems.

Question 18

What should a good communication protocol include?

Answer 18

How to set up a connection
How to end a connection
How to start a message
How to end a message
How to deal with corrupted data
How to format the data being sent.