Chapter9

Question 1

what are the 4 classes and explain

Answer 1

Conversational class - very delay sensitive for real time applications eg. telephony

Streaming class - one way communication little delay variation of end to end flow

Background class - less sensitive delay for background activity

Interactive class - less sensitive delay for interactive applications

Question 2

5 A and 3 D of Packet switching

Answer 2

A
1. Many people can use one channel
2. Improved delay characteristic as there are no long messages in the queue as packet is fixed size
3. Packet can be rerouted if there are any problems like busy or disabled links
4. Maximize link efficiency from optimal usage of link bandwidth
5. Cost effective as less secondary data storage on switching devices

D
1. Protocols for switching more complex so more expensive initially
2. Packets if lost need to be rerouted
3. Not same quality as dedicated circuits for video and voice streaming as

Question 2

What is the advantage and 3 disadvatages for circuit switching

Answer 2

Advantage:

1. The communications channel is dedicated once established

Disadvantage:

1. Long wait to establish a connection where no data can be transmitted
2. More expensive as there is one channel needed for each connection
3. Inefficient use of communication channel because channel is not used when systems are not using it

Question 3

Describe TCP

Answer 3

Transmission control protocol

1. Enables two hosts to connect and exchange streams of data
2. Guarantees delivery of data and guarantees order of data received

Question 4

Describe UDP

Answer 4

User datagram protocol
1. Connectionless and mainly used to broadcast messages

Question 5

Describe IP

Answer 5

Specifies packet format and addressing scheme

Question 6

4 layers of tcp

Answer 6

Application, transport, internet, network access

Question 7

What does network layer do

Answer 7

Concerned with all the issues a packet requires to actually make the physical link

Question 8

What does internet layer do

Answer 8

Send source packets from any network on the internetwork and have them arrive at the destination independent of the path and networks they took to get there.

Question 9

What does transport layer do

Answer 9

The transport layer deals with the quality-of service issues of reliability, flow control, and error correction.

Question 10

What does application layer do

Answer 10

Handles high-level protocols, issues of
representation, encoding, and dialog control.

The TCP/IP combines all application-related
issues into one layer, and assures this data is properly packaged for the next layer.