Week 04 (Layer Models)

Question 1

How are unicasting, multicasting and broadcasting message delivery options different?

Answer 1

Unicasting is messaging to a specific user/entity/process.

Multicasting is delivering and addressing a message to more than 1 users, but not all users who could receive it.

Broadcasting is messaging to everyone on a network.

Question 2

What are the 3 types of switching?

Answer 2

Package switching, message switching, circuit switching.

Question 3

What is encapsulation?

Answer 3

A process where when you receive data, you attach additional information to the start/end/both of the data, then forward it onto something else. You don’t touch the message or ‘payload’.

Question 4

What is decapsulation?

Answer 4

Stripping away the header or trailer information.

Question 5

What are the main benefits of a layer model?

Answer 5

FAPI - Fostering Competition, Assisting Protocol Development, Providing a Common Language, Isolating Problems.

Question 6

How does a layered model assigning protocol development?

Answer 6

You can work in one layer and not have it affect others. i.e. using specific/isolated information and interfaces.

Question 7

How does a layered model foster competition?

Answer 7

Products from different vendors can work together.

Question 8

How does a layered model isolate problems?

Answer 8

Changes made in one area are isolated there.

Question 9

Explain the benefit of a layered model providing a common language?

Answer 9

Supports teaching, learning and understanding…

Question 10

How are the OSI and TCP/IP layers fundamentally different?

Answer 10

The OSI layer is an international standard. There are 7 layers and there always will be. Whereas TCP/IP is an industry standard with a little more flexibility. For example Forouzan uses 5 layers and Cisco content uses 4.

Question 11

What are the 7 layers of the OSI model?

Answer 11

Physical, Data Link, Network, Transport, Session, Presentation, Application.

Question 12

What are the 4 layers of the TCP/IP model?

Answer 12

Network Access, Internet, Transport, Application.

Question 13

What does the Physical layer involve?

Answer 13

It involves bits, interfaces, power and signaling. The physical layer gets us from the sending device to the medium.

Question 14

What does the Data Link layer involve?

Answer 14

It involves physical addressing and framing, of flow control and error control from 1 link to another link (or one device to another device) within a network.

Question 15

What interconnects networks, and why is this important in relation to the data link layer?

Answer 15

Sort of a waffle, just generally explain.

Question 16

What does the Network Layer involve?

Answer 16

It involves logical addressing, allowing a message to go through/across a network of networks, from sending device to receiving device. It also finds the best route to do so.

Question 17

What does the Transport Layer involve?

Answer 17

It involve application addressing, of flow control and error control on an application basis. It also segmentation, i.e. the breaking up of data.

Question 18

What does the Session Layer involve?

Answer 18

It involves providing services to the presentation layer to organise dialogue and maintain data exchange.

Question 19

What does the Presentation Layer involve?

Answer 19

It involves translating the data into a common language, in a usable format for the application layer.

Question 20

What does the Application Layer involve?

Answer 20

Provides network services for end-user applications to work. i.e. the end-user ‘browser’ would require the network service ‘http’ to work.