Section 6 Chapter 32 - Network Topology

Question 1

LAN

Answer 1

A number of devices within a small area connected together, often confined to a single building or site

Question 2

Bus topology

Answer 2

All computers are connected to a single cable, with both ends having either a computer or a terminator

Question 3

Advantages of bus topology (2)

Answer 3

• Inexpensive as less cable needed and no special software needed
• New devices can be easily added

Question 4

Where bus topologies are used

Answer 4

Small networks that do not require high speeds

Question 5

Disadvantages of bus topology (4)

Answer 5

• If the main cable fails the whole network will go down
• Limited cable length and number of stations
• Performance degrades with heavy traffic
• Low security, all computers can see all data transmissions

Question 6

Operation of a bus network

Answer 6

Every station receives all network traffic and all traffic has equal priority. A device wanting to communicate sends a broadcast message that all nodes see but only the designated one processes

Question 7

What does CSMA/CD stand for

Answer 7

Carrier Sense Multiple Access with Collision Detection

Question 8

How CSMA/CD works

Answer 8

If two nodes simultaneously transmit a carrier sensing scheme detects it. Both nodes then stop transmitting and wait a random amount of time before transmitting again

Question 9

Star topology

Answer 9

All devices are connected to a central node which is usually either a hub or a switch

Question 10

Advantages of a star topology (4)

Answer 10

• Easy to isolate cable problems
• Good performance due to no collisions
• More secure as messages are only sent to their recipients
• Different stations can transmit at different speeds

Question 11

Disadvantages of a star topology (2)

Answer 11

• Costly to install due to length of wire

- If the central device goes down so does the whole network

Question 12

Difference between hub and switch

Answer 12

A switch sends data to the specific device it is intended for whereas a hub broadcasts the message to every device on the LAN

Question 13

Operation of a star network

Answer 13

Each node is connected to a single device, either a hub or a switch.
A hub takes an incoming signal and broadcasts it to all other nodes on the network, it is simply a junction.
A switch keeps a record of the MAC addresses of the devices and can identify which device to send to

Question 14

What does NIC stand for

Answer 14

Network Interface Card

Question 15

What does MAC stand for

Answer 15

Media Access Control

Question 16

What is a MAC address

Answer 16

A series of 48 bits hardcoded into the NIC that uniquely identifies a device on a network

Question 17

Physical topology

Answer 17

The actual layout of the wiring of the network

Question 18

Logical topology

Answer 18

The shape of the path that the data travels in. It describes how components communicate across the physical topology

Question 19

How can a network wired in start topology behave as a bus network

Answer 19

With a bus protocol and appropriate physical switching

Question 20

Which logical topology does ethernet use

Answer 20

Bus, regardless of the physical topology