1. 1.4 Wired and Wireless Networks
In this unit you will cover…

2. 2. LANs in Depth This lesson covers:
Factors that affect the performance of networks
The hardware needed to connect stand-alone computers to a LAN
Wireless Access Points
Routers
Switches
NIC
Transmission Media

3. We currently know What a network is
How we categorise networks based on:
Size
Ownership/Dedicated connections
Reasons why we network computers together:
Sharing (examples?)
Communication/collaboration

4. We now need to…
Discover how data actually gets from one machine to another…
…and what the various devices are that help us to do this.
BUT, before we can, we need to know what data actually looks like!

5. Packets
When data is sent on a network it is split up equally into “packets”
The sender splits data (a file, picture, web page etc) into packets and sends them off
The client receiving the data opens up the packets and puts the data back together.

6. Packets
Like a crisp packet is a container for crisps, a data packet is a CONTAINER for data.
Like the packet opposite, it doesn’t just hold stuff, it has extra information on it (flavour, size, brand).
A data packet also has extra information attached to it.

7. Packets Packets all carry the same basic information To: Gary Lineker
Destination: This ensures that the packet is delivered to the correct device
Sender: Where the packet has come from
To: Gary Lineker
From: Walkers
Packet number: 3
Best Before: 30/02/2017
Error correction data: Helps us repair the packet if it gets damaged
Data: The actual information we are sending!
Packet Life: How many “hops” is it allowed around the network before it vanishes?
If it can’t find its destination we don’t want it hanging around the network forever
Sequence Number: Which number packet is this? Remember, information is broken down into multiple packets; it needs putting back together in the right order!

8. Packets
Q: What happens if data arrives but packets are missing or corrupted?
A: The sender address is used – the destination computer can ask for these packets again
Q: Why is a sequence number needed?
A: Packets may be sent over different routes to the destination; they will not likely arrive in order (we’ll do more about this when we reach performance)

9. Addresses Every device on a network needs an address.
Imagine if data was just sent out without a specific destination – how does it know where to go?
We use IP Addresses on a network and every device has its own unique address
IP stands for Internet Protocol.

10. IP Addresses An IP address is: They are in the range:
4 Bytes long (32 bits)
Split by dots .
Each byte can have a value between 0 and 255 (obviously)
They are in the range: to
There are approximately 4.2 billion possible IP addresses

11. Papa John/Elton John – Same person?
Addresses - meaning
Think about ordering a pizza – Papa John’s don’t like it when you can’t give them an address; how do they know where to deliver the pizza?
Your address can be broken down into a few useful parts…
Chase Terrace Technology College – Individual house/property
Bridge Cross Road - Road
Burntwood – Town
Papa John is going to look at the town first, find the road in that town, then find the school on that road!
Papa John/Elton John – Same person?
Yes, this is why Mr. Cooper chose Papa John’s instead of Domino’s for this particular analogy.

12. Addresses
IP addresses can be broken down in a similar way…
Network: All devices on the same network will share this part
Subnet: The network can be divided into different sections (or subnets)
Host: This is the address of the individual device – this part is unique for every device
Network
Subnet
Host

13. Addresses IP addresses are not permanent.
The IP address of a device can change every time it is connected to a network
They can be dynamically assigned
This means you cannot use an IP to identify an individual device, only a destination that has been assigned to it

14. MAC Addresses
A device only gets an IP address when it’s joined the network; how do we know which address belongs to which device or if it’s a new device or not?
The answer is the MAC Address. Every network interface in the world has a unique MAC address
Media Access Control
These addresses are used to keep track of devices on a network
It’s still important to give devices IP addresses as these help to organise and separate the network

15. MAC Address 6 bytes long (IP is only 4) Usually written as HEX, e.g:
3F:AA:FB:2C:ED:D1
NEVER changes (assigned to physical hardware, for the life of that device)
NEVER re-used – even if an old device is destroyed
Used to uniquely identify individual pieces of hardware

16. MAC Addresses
If your computer has Ethernet and Wi-Fi, both the Ethernet and Wi-Fi NICs must have their own MAC addresses
A MAC address can be used for security – you could block specific MAC addresses or allow only MAC addresses that you know onto your network

17. Addresses
As IP Addresses are broken down into 4 bytes (or 32 bits, whichever way you’d rather remember it) we are limited by binary itself…
Each of the 4 sections are limited to the size of a single byte (255)
This is causing a genuine problem as the number of internet connected devices (each requiring an IP address) grows
Complete the research task on IPv4 vs IPv6…

18. Components of a LAN
There are some basic hardware components needed to create a Local Area Network
Find out about as many different pieces of network hardware as you can and throw them into the component investigation. No copy and pasting!
Think of it of a networking Pokedex (if that motivates your Pokemon Go addled brains)
Fibre NIC

19. Components of a LAN Router Switch Network Interface Card (NIC)
Wireless Access Point (WAP)
Transmission Media
You should now know exactly what each of these is but just in-case you’re not sure, we’ll whizz through…

20. Network Card (NIC) Can be wired or wireless
Usually built in to all modern devices
Enable your computer to send and receive data on a network
Will adhere to either a wired or wireless standard
Responsible for creating packets and sending data
Responsible for receiving and re-assembling packets of data

21. Hubs Before we had switches, networks used hubs
Hubs were properly stupid. They didn’t look at the destination of packets ,instead sending every single packet to every single device that was connected to it (they are called “broadcast” devices)
The clients then decided if the packets were for them or not and ignored those meant for other devices (Security? Workload?)
Never ever use the word hub when talking about networks in the exam – they’re dead and buried; no one mourns the wicked

22. Hubs Broadcast devices Send data to all connected devices
Workload passed on to clients
Create lots of traffic
Slow performance due to collisions
Cheap!

23. Switch
A collision
Switches look at the destination of each packet and send it on to that destination
If two or more computers send packets onto the network at the same time there would normally be a collision – switches solve this by receiving the packets, looking at the destination address and sending them on their way
The sender and recipient are unaffected by any additional traffic created by any other devices on the network

24. Switch Devices which use packet inspection
Looks at the destination and sends it there!
Sends only data to the intended recipient
Reduces network traffic
More expensive than a hub
May need to be configured by an administrator (cost)

25. Router This is the most “intelligent” device on the network
The router can actually decide which direction to send packets on the network to reach their destination
It may make this decision based on a number of things:
Traffic on the network, distance between clients, network capacity
The router keeps a routing table which stores the addresses of devices on the network and common routes that packets can take on the network

26. Router Used to connect networks to the internet
Connects networks to other networks on the internet
“intelligent” or “aware” of the state of the network it is connected to
Can communicate with other Routers to avoid network problems

27. Wireless Access Point (WAP)
A Wireless Access Point is fairly obvious, isn’t it?
It allows wireless devices to connect to a network
Packets are sent using radio waves (in a similar way that cordless phones and television/radio work)
The WAP broadcasts the network information and transfers wireless packets to and from wireless devices and onto the main network
This can include both Wi-Fi and Bluetooth

28. Transmission Media
Media is often used to describe something that carries data electronically
In this case we’re talking about the stuff that carries our network packets between devices
The most common is Ethernet (Cat5e or Cat6 cable) - this uses twisted pairs of copper cable
We also use fibre optic cabling and a number of wireless methods (including Wi-Fi, microwave, bluetooth, satellite)

29. Transmission Media Complete the transmission media investigation Media
Type
Maximum Speed
Maximum Distance
Advantages
Disadvantages
Ethernet
Wired – Twisted pair
1000mbps
Fibre Optic
Wi-Fi
Satellite
Bluetooth

30. Transmission Media https://www.youtube.com/watch?v=0TZwiUwZwIE
8M (take your pick out of the two!)