1 - Introduction

Question 1

What are data communications?

Answer 1

The exchange of data between two devices via some form of transmission medium.

Question 2

What are the 5 components of data communication?

Answer 2

1. Protocol (rules)
2. Sender
3. Message/Medium
4. Receiver
5. Protocol (rules)

Question 3

What is simplex delivery?

Answer 3

Only one direction of data, mainframe to data.

Question 4

What is half-duplex delivery? What’s an example?

Answer 4

Two direction transmission of data, only one at a time. Walkie-talkies.

Question 5

What is full-duplex delivery?

Answer 5

Two direction transmission of data, all the time

Question 6

What is a network?

Answer 6

A set of devices (or nodes) connected by communication links.

Question 7

What is the formula for number of links in a mesh topology?

Answer 7

N*(N-1)/2, N is number of stations.

Question 8

What is the minimum number of links for a star, bus, and ring topology?

Answer 8

N, the same as the number of stations.

Question 9

What are some advantages and disadvantages to mesh topology? What is an example?

Answer 9

Advantages:
- robust
- private
- easy to find faults
Disadvantages:
- Hardware (cabling, I/O ports)

Example: backbone connecting

Question 10

What are some advantages and disadvantages to star topology? What is an example?

Answer 10

Adv:
- less expensive than mesh
- private
disadv:
- if hub goes down everything does

Example: LAN

Question 11

What are some advantages and disadvantages to bus topology? What is an example?

Answer 11

Adv:
- easy to implement
disadv:
- difficult reconnection and fault isolation
- signal reflection causes quality degradation, hard to add new nodes

Example: LAN

Question 12

What are some advantages and disadvantages to ring topology? What is an example?

Answer 12

Adv:
- easy to implement, reconfigure
- fault isolation
disadv:
- unidirectional traffic, one break disables the entire network

Example: LAN

Question 13

What are some characteristics of LAN networks?

Answer 13

• Sharing in local area, a few km
• One type of transmission medium for a given LAN
• 4 Mbps -> more than 1G Mbps (modern day)

Question 14

What are some characteristics of WAN networks?

Answer 14

• Long distance transmission

- Can be very complex or as simple as dialup (point to point)

Question 15

What is circuit switching vs. packet switching?

Answer 15

Circuit: set up between two terminals for duration of conversation.
Packet: packet can follow different paths to destination, many connections, internet