Component 1 - Computer Systems - Section Two - Networks (LANs and WANs…
Component 1 - Computer Systems - Section Two - Networks
LANs and WANs
Local Area Network -
Why use a LAN -
6)User accounts can be stored centrally so users can log in from any device on the network.
1)Sharing files is easier, network users can access the same files and work collaboratively.
5)Communicate easily with instant messaging.
2)Share the same hardware like printers.
4)Install updates on all devices instead of one by one.
3)Internet can be shared between every device.
1)LAN covers a small geographical area located on a single site.
5)Lots of homes have a LAN to connect various devices, such as PCs, tablets, smart TVs and printers.
2)All the hardware for a LAN is owned by the organisation that uses it.
4)LANs are found in businesses, schools or universities.
3)Can be wired or wireless.
Factors can affect the Performance of networks -
4)Choice of hardware other than cables and network topology also have a big effect.
1)Bandwidth is the amount of data that can be transferred in a given time.
3)Weird connections are better, Fibre optic is better than copper cables, wireless connection depends on signal strength.
2)Available bandwidth is shared between users of a network too many users can cause congestion and slow the network.
Wide Area Network -
4)Internet is the biggest WAN.
1)WAN connects LANs that are in different geographical locations e.g. a business with offices in three different countries would need a WAN.
3)WANs may be connected using fibre or copper telephone lines, satellite links or radio links.
2)WAN is much more expensive to set up than LAN.
Communication between different networks uses IP addresses. IP addresses are used when sending data between TCP/IP networks over the internet. Unlike MAC addresses, IP addresses aren't linked to hardware. They are assigned either manually (static) or automatically (dynamic) before the device can access the network. Static IP addresses are permanent addresses. They're used to connect printers on a LAN, and for hosting websites on the internet - companies don't want the IP address of their website changing. Static IP addresses on the internet can be very expensive - businesses pay big money for them. Dynamic IP addresses are assigned when a device logs on to a network, meaning that it may have a different address every time it connects. Internet Service Providers (ISPs) commonly use dynamic IP addresses as they are a bit more cost effective and can be reused. An IP address can be a 32-bit or 128-bit binary number, depending on the version of the IP you're using. The longer 128-bit numbers are translated into eight hexadecimal numbers, while the 32-bit ones are converted into four denary numbers like in the example below.
Communication on the same network uses MAC addresses. Every device needs a unique identifier so it can be found on a network. MAC addresses are assigned to all network-enabled devices by the manufacturer. They are unique to the device and cannot be changed. MAC addresses are 48-bit or 64-bit binary numbers. To make them easier to use they're converted into hexadecimals. Mac addresses are mainly used by the Ethernet protocol on LANs. LAN switches read the MAC addresses and use them to direct data to the right device.
A protocol is a set o rules for how devices communicate and how data is transmitted across a network. Protocols cover how communication between two devices should start and end, how the data should be organised, and what the devices should do if the data goes missing.
Mesh: In a mesh topology, all devices are connected together directly or indirectly without a centralised server. This means that if one device fails, other devices will only disconnect from the network if the failed device is the only path to the other devices. Even if this happens, the disconnected devices can still function as their own separate network until they are reconnected.
Star: All devices are connected to a central switch or server that controls the network. Advantages - If a device fails or a cable is disconnected, the rest of the network is unaffected; it's simple to add more devices to the network; better performance than other setups (data goes straight to the central device so all devices can transfer data at once and there are very few data collisions). Disadvantages - In wired networks, every device needs a cable to connect to the central switch or server, this can be expensive; If there is a problem with the switch or server, the whole network is affected.