1. 1.4 wired and wireless networks lesson 2

2. The Big Picture: Wired and wireless networks
Types of networks:
LAN (local area network) & WAN (wide area network)
The different roles of computers in a client-server and a peer-to-peer network
Factors that affect the performance of networks
Network topologies
The hardware needed to connect stand-alone computers into a local area network:
Wireless access points
Routers/switches
NIC (network interface controller/card)
Transmission media
The internet as a worldwide collection of computer networks:
DNS (domain name server)
Hosting
The cloud
The concept of virtual networks

3. Thought for the day - Networks
At peak capacity, Netflix uses 1/3 of all Internet traffic in North America!

4. Starter: Recap P2P and C-S
Peer to Peer?
Client – Server?
1 -Each computer acts as a 'host'. Users can access files and peripherals directly from all the other nodes on the network.
5 - Each computer on the network has equal importance and no more privileges than any other.
6 - All computers on the network connect through a central hub or switch.
2 -The files are stored on the hard disks of individual network machines.
3 -Workstations cannot normally 'see' or share data with each other directly over the network.
7 - Very common in small offices or at home where there are only a few computers connected together.
4 - Users will have their own private area on the network where they can save their files and documents. No one else can access this area (except the network manager/staff).
8 - There may be multiple shared folders on a server with different access rights.

5. Starter: Recap - Network Types
Meaning
Example
LAN
WAN
PAN
VPN

6. Starter: Recap - Network Types
Meaning
Example
LAN
WAN
PAN
VPN
Local Area Network
School
Wide Area Network
Cash Dispensers
Laptop
Personal Area Network
Virtual Private Network
Mobile

7. Learning Objectives By the end of today’s lesson, you will:
Identify the components required to create a LAN
Describe the role of each component in a LAN
Understand what is meant by the performance of a network and why this is important
Explain the factors that can affect the performance of a network

8. Transfer of data over a network: Packets
Data transmitted over a network is broken down into packets.
Each packet contains the address of the sender and the address of the receiver (IP addresses)
Packets will also contain a sequence number so they can be re-packaged at the receiving end
Packets will have a time to live (how many hops around the network they can take before they disappear

9. Network Performance Latency Bandwidth
Network latency is how much time it takes for a packet of data to get from one designated point to another.
Latency is measured by sending a packet that is returned to the sender; the round-trip time is considered the latency.
Ideally, latency is as close to zero as possible.
Describes how much data can be transferred over a connection in a given time.
The speed of a network is measured in bits per second.
Ideally you would want as much bandwidth as possible to enable as much data as possible to be transferred within that second

10. Latency
Network latency is any kind of delay that happens in data communication over a network.
So you want a network with low latency as this will mean there is less of a delay in data communication between devices.
Latency prevents the data from taking full advantage of the available bandwidth. The problem could be temporary or ongoing depending on the issue.
Possible contributors to network latency include:
Problems with the transmission medium itself.
Errors with the router or switches as each gateway takes time to examine and change the packet header for the next part of the packets journey.
Anti-virus and similar security processes
The time it takes for a packet to physically travel from its source to a destination.
Storage delays when packets are subject to storage or disk access delays at devices like switches and bridges.
Software malfunctions at the user level can cause some delays from a user perspective.

11. Brainstorm What hardware do we need to create a LAN?
How will the computers be connected together and what might be required to do this?
What do we mean by the performance of a network and why this might be important?

12. Hardware components
What is the role of the following hardware components in a network?
Wireless access point (WAP)
Router
Switch
Network interface card (NIC)
Transmission media

13. Bandwidth
Bandwidth is also defined as the amount of data that can be transmitted in a fixed amount of time.
A LAN has bandwidth in the same way as a WAN such as the Internet has.
Your broadband provider will give you an idea of what your bandwidth is, often quoting the maximum available.

14. Network Hardware

16. Wireless Access Point (WAP)
Allows for wireless devices to connect to a network (either LAN or WAN)
Includes connections through Wifi and Bluetooth
WAPs provide Internet access in public places (often known as Wi-Fi hotspots)

17. Router
An interconnection device used on networks to connect two or more devices.
Routers contain a routing table which has a list of IP addresses and common routes for packets to take
Routers examine packets IP addresses
The router will apply a subnet mask to identify a network and determine which network the packet should be forwarded to
If the packet is for this network – the router determines which host to send the packet to
Routers allow packets from different network types to be exchanged

18. Switch
If two or more computers place a packet onto a network at the same time – a data collision occurs
A switch is an interconnection device that connects two or more devices together and helps in solving the issue of data collisions
As a data packet arrives at the switch – its destination address is examined and the switch creates a direct connection to that device
As far as the two devices are concerned there are no other computers on the network (see example)

19. NIC Network Interface Card
A network interface card allows a computer to connect to a wired network
A NIC allows data packets to travel to and from a computer
A NIC contains a MAC address which is a physical hardware address
A NIC allows an Ethernet cable to be plugged into this

20. Transmission Media Ethernet (Cat 5e / Cat6) Fibre optic Coaxial Cable
Known as twisted pair
A networking standard
Fibre optic
Very fast cable but also more expensive (often used with WAN or larger LANs)
Coaxial Cable
An older networking standard

21. How do packets travel around a network
How do packets travel around a network? (Practical class engagement task)
Have you ever been frustrated by your computer or mobile device working very slowly? What might be causing that to happen and what might be affecting the performance of the network you are trying to use?

22. Show your understanding
Match up the hardware term and its definition on the worksheet.

23. Network performance
Measures of computer network performance are commonly stated in units of bits per second (bps). This quantity can represent either an actual data rate or a limit to available network bandwidth.
Modern networks support very large numbers of bits per second. Instead of quoting 10,000 or 100,000 bps, networks normally express these quantities in terms of kilobits, megabits, and gigabits.
1 Kbps = 1 kbps = 1 kilobit per second = 1,000 bits per second
1 Mbps = 1,000 Kbps
1 Gbps = 1,000 Mbps
In networking, both "kbps" with a lowercase "k" and “
Kbps" with an uppercase "K" can be used interchangeably.

24. Show your understanding
Match up the hardware term and its definition on the worksheet.
Create a leaflet for a networking novice to explain:
The hardware components and their functions
How they can get the best out of their network - explain the factors that can affect the performance of a network and how these can possibly be overcome.

25. Plenary: Define Key Words
LAN
Packet
Wireless access point (WAP)
Router
Switch
Ethernet cable
Network interface card (NIC)
Transmission media
Network performance