Unit 3: Communication

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Unit 3: Communication by Mind Map: Unit 3: Communication

1. Advantages and Disadvantages

1.1. Advantages

1.1.1. Sharing resources such as printers saves money

1.1.2. You can access your files from any computer in the network

1.1.3. Data is easy to back up as it is stored centrally on the server

1.1.4. Use of messaging or email across the network

1.2. Disadvantages

1.2.1. Purchasing the network hardware is expensive

1.2.2. Managing a large network is complicated

1.2.3. Virus attacks on the network may infect every computer

2. WAN, LAN and PAN

2.1. LAN

2.1.1. Local area network uses cables and networking equipment owned either by one person or business at one local site or a group of nearby buildings

2.2. WAN

2.2.1. Wide area network use third party cables over a wide geographical area

2.3. PAN

2.3.1. Personal Area network uses a Bluetooth connection to connect headphones tablets and speakers

3. Packet and circuit switching nework

3.1. Circuit switching uses one single route/cable and is susceptible to interference and failure of one section results in the entire failure

3.2. Packet switching uses many different routes and resulting in the data being split up into packets then reassembled at the other end

3.2.1. Each data packet will contain the same number of bytes decided by the NIC and each packet is marked with the total number of packets

3.2.2. Lost packets, the recipients computer uses check sum to check for lost packets. Packets after a set time will be automatically be resent

3.2.3. Nodes/ routers pass the packet through the path that is least busy

4. Networks

4.1. A network is a series of computers and other devices that are connected together and can share data and resources

4.1.1. The biggest network in the world is the Internet

4.2. The World Wide Web is a way of accessing information over the internet using HTTP (hypertext transfer protocol) to display webpages

4.3. Bus, Star and Mesh

4.3.1. Bus Advantages Less cable needed so cheaper to set up Easy to install Disadvantages More collisions with lots of machines on the network If the main cable is damaged or fails, the whole network fails Every workstation “sees” all the others – security risk

4.3.2. Star Advantages Fast data transfer as there are fewer data collisions – data goes from the switch to the workstation that requested it If one cable fails the other workstations are not affected Disadvantages Requires additional hardware such as the central hub or switch If the central device fails the whole network goes down

4.3.3. Mesh Advantages They don't need a router so there is no single point of failior Disadvantages If they are wired the cabling can be expensive

5. DNS Domain Name Sever

5.1. DNS converts a web address into and ip address e.g www.google.com =

5.2. There are 13 main (root) servers that have a complete database of all names and IP adresses

6. IP addressing

6.1. Every computer and other device connected to the Internet has an private IP address given out by the router

6.2. ISP give each router a public IP address which can change over time

6.3. Packets are labelled with the senders and destination IP address

7. MAC addressing

7.1. Media Access Control is assigned to each NIC by the manufacturer a device can have two MAC addresses one for WIFI one for Wired

7.2. Every networked device has a unique MAC address

7.3. MAC address never changes IP does depending on loaction

8. Wired VS Wireless

8.1. Wired

8.1.1. Benefits Faster connection Higher bandwidth Greater security

8.1.2. Risks Cables can be hazardous and unsightly Not all devices can connect via cable Can be expensive to set up

8.1.3. Fibre Mostly used for long distance transmission no signal degridation Very expensive, requiring specialist networking hardware Superfast connection with much greater bandwidth Signals travel as pulses of light so cannot be affected by stray electromagnetic signals

8.1.4. Ethernet Copper Used for most shorter connections as much cheaper Signal deteriorates significantly over distance Signal repeaters are required every 100m Signals affected by electrical interference Ethernet protocols (set of rules)

8.2. Wireless

8.2.1. Benefits No wires Easy to connect new devices Can be used freely within range

8.2.2. Risk Connection can be slower Subject to interference from walls, objects and other electronic devices Less secure Theft of bandwidth from neighbouring users within range Compromised confidentiality without adequate encryption Easier to intercept data or ‘hack’

9. Routing Costs

9.1. Shortest path and Reliability

10. Protocol

10.1. Set of Rules

10.2. FTP File Transfer Protocol

10.2.1. Used for sending files like file explorer

10.3. HTTP HyperText Transfer Protocol

10.3.1. HTTPS encrypts information

10.4. SMTP

10.4.1. Simple Mail Transfer Protocol

10.5. POP3 IMAP

10.6. UDP

10.6.1. Doesn't check if packets are received correctly uselful for Online games skype calls

11. TCP/IP

11.1. Application layer

11.1.1. The application selects the correct protocol to use depending on which application it is and what you are trying to do

11.2. Transport Layer

11.2.1. Creates a connection between the two computers

11.2.2. Decides on packet size

11.3. Network Layer

11.3.1. Destination addresses are written on to the packets

11.4. Link Layer

11.4.1. Physical Hardware conection