1.4 Network revision

Master computer networks! Understand WAN, LAN, models, hardware, and performance factors.

The largest WANon the planet is the internet. The internet also uses different models - such as the client-server model and the P2P (peer-to-peer)model - to connect computers in different ways. A WAN (wide area network) is created when LANs are connected. True False Choose the advantages and disadvantages of a wired and wireless network. Wired installation is difficult cost of equipment and time Security is good needs to be physically connected No interference Mobility is poor as limited by the infrastructure setup Wireless installation is easy just need a WAP Security is poor, anyone within range can access Signal can be effected by physical items and other electronic devices Access can be from anywhere within range Bandwidth is slower Factors that affect performance Bandwidth The amount of data that can be transferred per second Number of users More of these will cause congestion. less bandwidth per one Latency A period of delay in the speed of the network Transmission media Wireless or wired (CAT5, Coaxial,Fibre optic) A switch performs a similar role to a hub and a bridge but is more powerful. It stores the MAC addresses of devices on a network and filters data packets to see which devices have asked for them. This makes a switch more efficient when demand is high. If, for example, a game involved lots of data being passed between machines, then a switch could reduce the amount of latency. A router can form a LAN by connecting devices within a building. It also makes it possible to connect different networks together. Homes and businesses use a router to connect to the internet. A router can often incorporate a modem within the hardware. Cables Ethernet Cable CAT 5, CAT 5E, CAT6 Twisted pair Combined cables to reduce interference Coaxial Made with a single copper wire Surrounded by a plastic layer Outer layers provide shielding from outside interference Fibre Optic Transmit data as light High performance expensive do not suffer interference over large distances In a client server network the advantages are: (tick all that apply) Easier to keep track of files as they are centrally stored Easier to install software You do not need any expensive hardware All devices are equal In a Peer-to-peer network the advantages are: (tick all that apply) Easier to keep track of files as they are centrally stored Easier to install software You do not need any expensive hardware All devices are equal The internet and the WWW The internet is a network of networks, it's a WAN which connects devices and networks from all over the world. Using the protocol TCP World Wide Web is a collection of websites that are hosted on web servers and accessed through the http and https protocol. URLs are addresses used to access web servers and resources on them. The domain name server (DNS) will translate a website domain name in its IP address. The cloud Hosting is when a business uses its servers to store files of another organisation. The traditional use for this is the hosting of websites. A relatively recent use is of general storage of users files and also providing online software. this is cloud computing. It acts like an extension of a traditional client-server network where user files are stored centrally. Advantages of the cloud Users can access from any connected device Easy to increase how much storage is available No need to purchase expensive hardware No need to pay for IT staff to maintain hardware security and back ups are provided Software is automatically updated Disadvantages of the cloud Needs an internet connection dependent on the host for security and back-ups Data can be vulnerable to hackers Unclear who has ownership of the data Subscription fees may be expensive over time Network components A hardware component required to connect any device to a network. Nearly all devices have a NIC built directly into the motherboard. A MAC address is assigned to this and is created at the manufacturing stage. Client server models Select whether each item is an advantage or disadvantage of a client server model. Advantage Storage of files is central so users can access them from any computer. Files are kept organised and in sync Backups are made centrally. Not relying on individuals to run backups on every PC. Security is managed centrally Software can be installed and maintained centrally Disadvantage Requires a costly maintenance team to manage the network and server Too many requests will have an impact on the server performance If the server goes down then the service is lost for the network Key network hardware Router Directs packets of data from one network to another. They sit between the LAN and the WAN. Wireless access point (WAP) Turns the signals from cables into radio waves Switch Used to connect the devices on the LAN. Receives data packets and forwards them to the correct device based on the MAC address. Network Interface Card A hadware component required to connect any device to a network. Packets In order to send files, images, videos etc on a network they need to be broken down into packets. Each packet has key information kept in the header area. These are:Destination IP addressOrigin IP addressPacket numberPacket sequence numberCheck digit. (error checking) Peer to peer network a P2P network has no central server. All nodes are equal and share resources such as files. P2P networks are commonly used in small offices or homes where it is not cost effective to have specialised network support and a server. The configuration could be wired or wirelessDraw a P2P network for a home network that includes two PCs, one laptop and a tablet device. Data packets Below is the key material included in packet headers