Computer Networks (Network Devices (Modem, Switches, Router, Network Hubs,…
Common types of network
Allows users to save and load data files
Deal with distribution of applications software to each computer
Used as a buffer between WANs and LANs
Ensure printing from devices on the network is done in a queue
Local Area Networks(LANs)
Easy communication between users
Sharing of resources(expensive peripherals)
Can easily monitor all aspects of network.(changing passwords)
Easy to spread virus throughout the whole network.
If main server breaks down,networks will not function.
Slower access to external networks,such as the internet.
Consists of a number of computers and devices which will be connected to hubs or switches.
Usually within one building,maximum less than a geographical area.
One of the hubs or switches will usually be connected to a router or modem to allow the LAN to connect the internet.
Wireless LANs (WLAN)
Security is a big issue since anyone with a WLAN-enabled laptop computer can access a network if it can pick up a signal. That is the reason why you should use complex data encryption techniques.
The data transfer rate is slower than a wired LAN.
There may be problems of interference which can affect the signal.
Similar to LANs but there are no wires or cables.
Provide wireless network communications over fairly short distances(a few metres) using radio or infrared signals.
The system is more flexible,since users can move their laptops from their desks.
All computers can access the same services and resources;printers and scanners.
There is no cabling to individual computers and devices so safety is improved.
Problems on the network are easy to identify and work can be carried out on a faulty device without affecting the rest of the network.
It is easy to expand the network.
If one computer or device fails, then the rest of the network is unaffected.
If the central hub breaks down, the whole network crashes.
Data is sent to the hub which thens send out data along every cable to every computer or device.
Each computer or device is connected via a central hub or switch.
Easy to add a new computer or device to the network.
If one device or computer fails,it does not affect the rest of the network.
Does not need a hub or a switch and also requires less cabling.
Becoming an increasingly outdated topology for network design.
If the central line has a fault,the network fails.
It is difficult to isolate any fault on the network.
Each computer or device is connected to a common central line.
The ends of the lines have terminators to prevent signal bounce which would cause interference.
Data travel alongs this central line until it reaches the computer or device that requires it.
It is possible to create very large networks using topology.
Ring networks work well under heavy loading.
If there is a fault in the wiring between the 2 computers,then the whole network will fall.
Adding a new device or computer to the network can be difficult since it has to be placed between 2 existing devices.
Allows each computer to send and receive data since they all have a unique identification.
Data is transmitted around the ring.
Only removes data which is relevant to it
Every computer in the network is connected in a ring,including the server.
WAN(Wide area network)
A wide area network is a telecommunications network or computer network that extends over a large geographical distance/place.
Wide area networks are often established with leased telecommunication circuits.
Examples: 1.On the WLAN described above 2.PDAs and other handheld devices 3.Laptop computers which are WiFi enabled.
Refers to any system where it is possible to connect to a network through wireless communications.
Example of a wireless personal area networking (WPAN) technology.
With this system, it is possible to create a small home network,for example, to allow communication between any PDA,mobile phone,computer,media player and printer. The range is however,quite small(about 10 metres).
Radio waves (spread spectrum transmission) are used to provide links between mobile phones,computers and handheld devices and allow connection to the internet.
All of the disadvantage and advantage of tree networks are same like bus and star networks.
The server is also connected to this central line.Because of its flexibility,and the fact that it has the advantages of both star and bus networks,this topology is becoming increasingly popular.
Has a central line(like a bus network) connecting together a series of star networks.