Week 8 - Intro To Networks

Question 1

Define Internet

Answer 1

An interconnected group of networks

Question 2

Define Computer network

Answer 2

A group of computers that communicate with each other

Question 3

What is Networking?

Answer 3

It is about sending messages over a carrier.

Question 4

In a network what does it consist of?

Answer 4

It consist a set of ‘nodes’ which is connected by ‘links’.

Different networks have different. Switching schemes.

Question 5

Define Nodes

Answer 5

It represents the senders/receivers and switches ( a node that connects other nodes together.

Question 6

What are the three types of the switching scheme?

Answer 6

1. Broadcast network
2. Circuit-switching network
3. Packet-switched network

Question 7

What is a broadcast network?

Answer 7

• No switches
• Everything is transmitted to everyone
• Everyone receives everything

Question 8

What is a circuit-switching network?

Answer 8

• Each switch has multiple links
• A single communication session takes place on a dedicated,direct connection between the sender and receiver
• Guaranteed performance, but only two conversation can happen on this network.

Question 9

What is a packet-switching network?

Question 10

Why is the internet a packet-switched network?

Answer 10

This is because packets are the logical unit of information transmitted over the internet and they contain a data item of restricted length, including addressing information.

Question 11

What are the three structure of the internet?

Answer 11

1. Network edge
2. Access Network
3. Network Core

Question 12

Briefly explain the internet

Answer 12

It consists of billions of computing devices (hosts), the communication links between them, the routers and packet switches which forward chunks of data on those links.

Question 13

What does ‘ Network Edge’ do in the internet?

Answer 13

• Consists of the hosts/end-system, both clients and servers
• Hosts send packets of data to their access network

Question 14

What does ‘Access Network’ do in the internet?

Answer 14

• The physical wired/wireless communication links that connect edge system to the core.
• It is the first routers that see the data packets and forward them to the ‘network core.’

Question 15

What does ‘Network Core’ do in the internet?

Answer 15

• Central network of networks: a mesh of interconnected routers.
• The core routes and forwards packet of data from their source to their destination.

Question 16

What is the function of a ‘Host’?

Answer 16

• A host runs many ‘network applications’

Question 17

Where does the Host connect to? Provide examples of ISPs

Answer 17

Hosts connect to the internet via Access ISPs ( Internet Service Providers), where it could be residential ISPs, company/university ISP, mobile ISP, etc.

Question 18

What are the 2 things when identifying which ISPs to use?

Answer 18

1. Consider bandwidth required of the access network
2. Should the access network be shared or dedicated?

Question 19

What are the 3 Network Access?

Answer 19

1. Home Access Network
2. Enterprise Access Network

3.Wireless Access Network

Question 20

Why is the internet complex?

Answer 20

Any two hosts must be able to communicate with each other, which means the number of connections required is O(n^2). This means there is 1,000,000,000,000 internet hosts resulting to 1,000,000,000,000,000,000 connections.

Question 21

How does the complexity of the network handled?

Answer 21

By the network core

Question 22

How to go from an Access ISPs to global ISPs?

Question 23

Routing and forwarding

Question 24

What are 2 key functions of packet-switching?

Answer 24

1. Packet-routing: Determines source-to-destination route taken by packets
2. Packet forwarding: Move Packets from router’s input to appropriate router output.