Week 1: 2

Question 1

The file transfer program can call upon the services of the Network Access Module. What is the Network Access Module?

Answer 1

It’s the module that simplifies the implementation of the file transfer program.

Question 2

What does a network use to send data from one location ot another?

Answer 2

A combination of HW and SW

Question 3

Transmission of data is complex due to numerous things
that can go wrong. List these things:

Answer 3

• Data arrives with errors
• Data arrives correct but out-of-order
• Data arrives correct but parts are missing
• Data arrives correct but duplicated
• Congestion among links

Question 4

What is Layering?

Answer 4

A structuring technique to organize networking software design and implementation

• Layering model is the solution to the problem of
  complexity in networking
• Divide a task into pieces and then solve each piece
  independently (or nearly so).
• Establishing a well defined interface between layers
  makes porting easier.
• Major Advantages:
  .. Code Reuse
  .. Extensibility

Question 5

What is a protocol suite?

Answer 5

A set of related protocols designed for compatibility

Protocol suite designers:
* Analyze communication problem
* Divide problems into sub-problems
* Design a protocol for each sub-problem

A well-designed protocol suite:
* Is efficient and effective - solves the problem without redundancy
and makes best use of network capacity
* Allows replacement of individual protocols without changes to
other protocols

Question 6

What is the TCP/IP?

Answer 6

The layered protocol stack that dominatws data communications and networking today

Each layer calls upon the services of the layer below and
provides services to the layer above

Question 7

List the TCP/IP layers:

Answer 7

1. Physical
2. Data link
3. Network
4. Transport
5. Application

Question 8

What does the Physical Layer do?

Answer 8

• Coordinates the functions required to transmit a bit stream over a physical medium

• Usually the focus of an electrical engineer

It is concerned with:
* Physical characteristics of interfaces and media
* Representation of bits
* Data rate
* Line configuration
* Physical Topology
* Transmission mode
* Synchronization of bits

Question 9

What does the data link layer do?

Answer 9

It is responsible for node-to-node delivery.

It makes the
physical layer appear error free to the
network layer

Responsibilities of the data link layer include:
* Framing
* Physical Addressing
* Flow Control
* Error Control
* Access Control

Question 10

What does the network layer do?

Answer 10

It’s responsible for the source-to-destination delivery of a packet across multiple networks.

Responsibilities of the network layer include:
* Logical Addressing
* Routing
* ‘Accounting’ Tasks
* Protocol Conversions

Question 11

What does the transport layer do?

Answer 11

It’s responsible for the process-to-process delivery of an entire message across multiple networks.

Responsibilities of the transport layer include:
* Service-point (Port) Addressing
* Segmentation and Reassembly
* Connection Control
* Flow Control
* Error Control

Question 12

What does the application layer do?

Answer 12

It enables the user to access the network.

It provides user inerfaces and support for services

Question 13

What is the OSI model?

Answer 13

A model of how protocols and
networking components should
be made.

Question 14

What’s the uses of OSI model?

Answer 14

To:
* Analyze
* Compare
* Troubleshoot

Question 15

List the Layers of the OSI Model:

Answer 15

1. Physical
2. Data-link
3. Network
4. Transport
5. Session
6. Presentation
7. Application