Section 3: LAN and smaller network concepts (11.2.1)

What is eavesdropping?

Eavesdropping is the interception or monitoring of data being transmitted over a communication channel.

Attenuation

Attenuation is the weakening of a signal as it travels over a communication channel.

Crosstalk

Crosstalk occurs when a signal from one communication channel interferes with a signal in a nearby channel.

Electromagnetic interference

EMI is interference caused by electromagnetic from another electrical or electronic source.

How does twisting UTP wires reduce interference?

It helps reduce crosstalk

Why is fibre resistant to EMI?

Fibre transmits data using light pulses rather than electrical signals

What is the difference between attenuation and interference

Attenuation weakens the signal

Interference disrupts the signal

What is bluetooth?

Bluetooth is a short-range wireless communication technology that is used to exchange data between nearby devices

What is wireless communication?

Communication that transmits data without a physical cable.

What is network topology?

Network topology is the physical or logical arrangement of devices and connections in a network

Describe a star topology

All devices connect to a central device, usually a switch

Advantages of a star topology

1. If one cable/device fails the rest of the network can continue working

2. Easy to add/remove devices

3. Easy to identify/troubleshoot a faulty connection

4. Good performance because devices have dedicated connections to a switch

Disadvantages of a switch

1. If the central switch fails the whole network can be affected

2. Requires more cabling than a bus topology

Describe a bus topology

All devices connect to one main cable called a backbone

Advantages of a bus topology

1. Uses less cabling than a star toplogy

2. Relatively simple and inexpensive for small networks

Disadvantages of a bus toplogy

1. If the main backbone cable fails, the network can be disrupted

2. As more devices use the shared cable, the network performance can decrease

3. Troubleshooting can be difficult

4. Limited scalability

Describe a ring topology

Each device is connected to two other devices, forming a closed loop

Advantages of a ring topology

1. Data travels in an organised manner

2. Each device has an equal connection to the network

3. Can provide predictable performance because devices share access in an organised way.

Disadvantages of a ring topology

1. If one device/connection fails, the whole network can be disrupted depending on the implementation

2. Adding/removing devices can be more difficult

3. Troubleshooting can be more diffcult

Describe a mesh toplogy

Devices have multiple connections to other devices

Advantages of a mesh toplogy

1. Very reliable because there are multiple possible paths for data to travel

2. If ONE connection fails, data can potentially use another path

3. No single connection can’t necessarily cause the whole network to fail.

Disadvantages of a mesh topology

1. Requires a large amount of cabling

2. Expensive

3. More difficult to install and manage

4. Becomes increasingly complex as more devices are added

Describe a hybrid toplogy

A hybrid topology combines two or more different network topologies

Advantages of a hybrid topology

1. Flexible

2. Can be designed to suit the needs of different parts of a network

3. Combines the advantages of different toplogies

4. It is easier to expand a large network in sections

Disadvantages of a hybrid topology

1. More complicated to design and manage

2. Can be more expensive

3. Can be more difficult to troubleshoot

What is IPv4

IPv4 is a 32-bit addressing system that uses four decimal numbers separated by full stops to identify devices on an IP network.

What is IPv6?

IPv6 is a 128-bit addressing system that uses hexadecimal numbers separated by colons to identify devices on an IP network

Why was IPv6 introduced?

IPv6 was introduced because it provided a vastly larger address space than IPv4

What is a MAC address

A MAC address is a unique identifier assigned to a network interface, used to identify a device on a local network

What does MAC stand for?

Media Access control

What is DNS?

DNS is a system that translates domain names into IP addresses

What does DNS stand for?

Domain name system

What is DHCP

DHCP is a protocol that automatically assigns devices IP addresses and other network configuration settings

What does DHCP stand for?

Dynamic Host Configuration Protocol

What is ARP?

ARP is a protocol that finds the MAC address associated with a known IPv4 address in a local network.

What does ARP stand for?

Address resolution protocol

What is broadcast communication

Broadcast communication is a method of communication where one devices sends data to all the devices on a network or within a particular Broadcast domain.

What is point-to-point communication

Point-to-Point communication is a method of communication where data is sent from one device to one specific destination device.

What is the basic difference between broadcast and point-to-point communication?

Broadcast is one-to-many, while point-to-point is one-to-one.

Give an example of broadcast communication

An ARP request sent to devices on a local network

What is the main advantage of point to point communication over broadcast?

Data is sent only to the intended destination, therefore reducing unnecessary network traffic.

What is a packet?

A packet is unit of data at the network layer that contains an IP header and a payload

What is an Ethernet frame?

An frame is a data unit used at the Ethernet/Data-link layer

What is a payload?

The payload IS the actual data being carried by a packet or frame

What is a header?

A header is control information placed at the beginning of a packet or frame

What information does an IP header contain?

1. Sources IP address

2. Receivers IP address

3. Protocol

4. Packet number

What information does an Ethernet header contain?

1. Sources MAC address

2. Receivers MAC address

3. Optional VLAN tag

What is a frame check used for?

A frame check is used detect whether data in a packet has been corrupted during transmission.

What is a VLAN tag

A VLAN tag is information added to an Ethernet frame to identify the VLAN to which the frame belongs.

Why can the Ethernet frame change as a packet travels through networks?

The Ethernet frame changes at each network link so that frame can be delivered to the appropriate device on the next network link.