Client-Server and Peer to Peer networks 1.4 – Wired and Wireless Networks 15/11/2018 Client-Server and Peer to Peer networks

1.4 – Wired and Wireless Networks Re-cap A Local Area Network allows computers to share resources and data with each other. There are two main ways to connect computers on a LAN. These are: Client-Server Peer-to-Peer

1.4 – Wired and Wireless Networks Client-Server LAN In a Client-Server LAN arrangement, most files and data are stored on a server. All computers on the network connect to this server through a central hub or switch. The other computers on the network are called 'workstations' or 'clients'. Users can access files and data from the server using any workstation. They just need to log into their account using their username and password. If people need to share data then a 'shared network folder' is created on the server by the network manager in order to share files.

1.4 – Wired and Wireless Networks Client-Server LAN 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 and staff). A client server network requires a specialist network operating system. As files are stored on the server and they can be backed up centrally.

Advantages of a Client-server network 1.4 – Wired and Wireless Networks Advantages of a Client-server network With a single central server, files can be backed up more easily Installation of new software to the network is easier and faster Software only has to be licensed to the server itself Client machines (workstations) do not need much software or file storage of their own. Simpler to manage security and permissions for large networks

1.4 – Wired and Wireless Networks Peer to Peer Peer to peer networks are very common in small offices or at home where there are only a few computers connected together. With a peer-to-peer network a central server is not required because the files are stored on the hard disks of individual network machines. Each computer on the network has equal importance and no more privileges than any other. Each computer is both a client and a server - it acts as a 'host'. And users can access files and peripherals directly from all the other peers on the network. Example: Playing video from smartphone on TV

Advantages of a peer-to-peer network 1.4 – Wired and Wireless Networks Advantages of a peer-to-peer network Cheaper and less secure network model No single central point of failure. If one peer goes down, the others can continue to function. Easier to manage with small networks, for example two or three computers in a small office

1.4 – Wired and Wireless Networks Summary: Copy Table

1.4 – Wired and Wireless Networks Network Hardware LO: To be able to demonstrate an understanding of network types and the hardware used to set them up.

1.4 – Wired and Wireless Networks Activity: Research You need to research into the 5 key hardware used in networking: Network Interface Card (NIC) Hub Switch Router Wireless Access Point For each one, find out what it is, how it works and the key features. LO: To be able to demonstrate an understanding of network types and the hardware used to set them up.

1.4 – Wired and Wireless Networks Network Topologies

What is a Network topology? 1.4 – Wired and Wireless Networks What is a Network topology? It is the physical layout of connections in a network. Each device within a network is called a 'node'. A node could be a workstation, a printer, a server etc Each of these nodes is connected to other nodes either by cable or Wi-Fi.

1.4 – Wired and Wireless Networks Star Topology The star network topology has a central device directly connected to all other nodes. Just like a star shape. The central node could be a hub, a switch or a server. Uses of a star topology The star topology is very popular in an office or small company because it is very efficient, relatively low cost, and fairly simple to set up.

Star network Pros and Cons 1.4 – Wired and Wireless Networks Star network Pros and Cons Advantages Star networks are very reliable. If one connection fails, it does not affect other users Very few data collisions as each node has its own cable to the server Good security - no workstation can interact with another without going through the server first Simple to add or remove a node as it has no effect on any other node Scalability - can add many new nodes. Disadvantages The most expensive network layout to install because lots of cables needed Installing the network usually needs experts to set it up Extra hardware such as hubs and switches may be needed If the central switch or server fails, the whole network is down Requires a high performance switch or server in the centre as all traffic passes through it.

1.4 – Wired and Wireless Networks Mesh Topology In a mesh network there is no central node in a mesh network. Each device connects to every other device and exchanges data with devices within reach. Advantages over a star topology: Excellent wireless range  Very Robust Uses of Mesh network topology Music streaming devices, In factories, The military, Surveying, Rescue service and Mobile hot-spots. 

Mesh network Pros and Cons 1.4 – Wired and Wireless Networks Mesh network Pros and Cons Advantages Very robust network. If one path fails, the rest can still be used There is no central node to fail Excellent for wireless networks as each node re-broadcasts all the data packets it receives. It can handle very high data traffic rates Data packets can be sent simultaneously Devices can join or leave the network without affecting the overall network. Disadvantages The number of connections increase massively as more nodes are added Rapidly becomes an impractical topology for wired network as so many cables would be needed. Very expensive for a wired network due to cabling and switches needed Needs complex co-ordination to be effective

1.4 – Wired and Wireless Networks Transmission Media

1.4 – Wired and Wireless Networks Cable Traditional method of networking Usually a combination of twisted pair cable and Fibre optic cable Copper cable carries the data as electric current, and in fibre optical cable they are transmitted as pulses of light generate by a light emitting diode or laser Fibre optic cables have a greater bandwidth and can carry signals far faster than copper cables. The signals can also travel without being boosted. To transmit data over cables, there are rules called protocols. The controls how data is packeted and how collisions are detected or prevented. The most widely used standard is Ethernet

IP addressing, MAC addressing, and protocols 1.4 – Wired and Wireless Networks IP addressing, MAC addressing, and protocols

1.4 – Wired and Wireless Networks IP Addressing Each device on a network needs to be uniquely identified so that data can be sent to the correct destination, much like an address on a letter. This unique address is called an IP address. Internet Protocol (IP) is a set of rules that govern the activity on the internet and WWW. An IP address is a theoretical address, this means that it is assigned to your computer, but you could change it (Dynamic), or specify your own.

1.4 – Wired and Wireless Networks IP Addressing The IP address allows you to send and receive data over the internet. They provide information such as your devices location in the world, right down to the city. It is possible to use a look-up service to find out where people are based through their IP addresses. IP addresses can be either static or dynamic. Static IP addresses are permanent and never change. Dynamic IP addresses are temporary and are assigned to the device every time it accesses the internet. Your device will have a different IP address each time it joins a network to access the internet.

1.4 – Wired and Wireless Networks MAC Addressing MAC Address is a unique physical address on the network card on your computing device. It is assigned on a chip when made in a factory and cannot be changed. (Every device has its own). Made up of hexadecimal numbers. 0A-14-FF-32-11-23

1.4 – Wired and Wireless Networks Network Protocols A network protocol is an agreed way of how to communicate over a network. A protocol is often made formal by setting up a world standard. A protocol is a rule that all computers on network must operate by. Computers can only communicate if they follow the same protocols. In terms of network communications having a protocol standard allows devices to exchange data with one another as long as they are all following the same rules.

1.4 – Wired and Wireless Networks Network Protocols A good communication protocol should include the following details: How to set up a connection How to end a connection How to start a message How to end a message How to deal with corrupted data How to format the data being sent

1.4 – Wired and Wireless Networks Network Protocols The protocol used for communicating over the internet is called TCP/IP, or "Transmission Control Protocol / Internet Protocol". It has two parts: TCP and IP. 20 mins

1.4 – Wired and Wireless Networks Key points HTTP, or "HyperText Transfer Protocol", is the protocol underlying the World Wide Web. Web pages are sent and received using the http protocol. There is a variation of it called 'https' (extra s on the end), meaning 'http secure'. This protocol works like http, but also encrypts web page data before it is sent out of the browser or server, to make sure that nobody can intercept the data and read it themselves.

Questions: Network Protocols 1.4 – Wired and Wireless Networks Questions: Network Protocols 1a. What does the word ‘protocol’ mean? 1b. What is a ‘network protocol’? 1c. List the things that a good communications protocol should include. 2. Explain the role of the TCP/IP protocol. 3a. Explain the role of the HTTP protocol 3b. What is the difference between HTTP and HTTPS? 4. What is the role of the FTP protocol? 5a. What is the role of the POP protocol? 5b. What are the disadvantages of the POP? 5c. How does IMAP differ to POP? 6. What is the role of Ethernet protocols? Hint: You will need to do some research to answer some of these!