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Computer Networks (Network Devices (Bridges, Network Hubs, Router,…
Computer Networks
Network Devices
Bridges
Network Hubs
Router
Switches
Modem
Common types of network
Printer servers
Ensure printing from devices on the network is done in a queue
Proxy servers
Used as a buffer between WANs and LANs
Application servers
Deal with distribution of applications software to each computer
File servers
Allows users to save and load data files
Local Area Networks(LANs)
Facts
One of the hubs or switches will usually be connected to a router or modem to allow the LAN to connect the internet.
Usually within one building,maximum less than a geographical area.
Consists of a number of computers and devices which will be connected to hubs or switches.
Disadvantages
Slower access to external networks,such as the internet.
If main server breaks down,networks will not function.
Easy to spread virus throughout the whole network.
Advantages
Can easily monitor all aspects of network.(changing passwords)
Sharing of resources(expensive peripherals)
Easy communication between users
Ring Networks
Facts
Every computer in the network is connected in a ring,including the server.
Only removes data which is relevant to it
Data is transmitted around the ring.
Allows each computer to send and receive data since they all have a unique identification.
Disadvantages
Adding a new device or computer to the network can be difficult since it has to be placed between 2 existing devices.
If there is a fault in the wiring between the 2 computers,then the whole network will fall.
Advantages
Ring networks work well under heavy loading.
It is possible to create very large networks using topology.
Bus Networks
Facts
Data travel alongs this central line until it reaches the computer or device that requires it.
The ends of the lines have terminators to prevent signal bounce which would cause interference.
Each computer or device is connected to a common central line.
Disadvantages
It is difficult to isolate any fault on the network.
If the central line has a fault,the network fails.
Becoming an increasingly outdated topology for network design.
Advantages
Does not need a hub or a switch and also requires less cabling.
If one device or computer fails,it does not affect the rest of the network.
Easy to add a new computer or device to the network.
Star Networks
Facts
Each computer or device is connected via a central hub or switch.
Data is sent to the hub which thens send out data along every cable to every computer or device.
Disadvantages
If the central hub breaks down, the whole network crashes.
Advantages
If one computer or device fails, then the rest of the network is unaffected.
It is easy to expand the network.
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.
Wireless LANs (WLAN)
Advantages
There is no cabling to individual computers and devices so safety is improved.
All computers can access the same services and resources;printers and scanners.
The system is more flexible,since users can move their laptops from their desks.
Facts
Provide wireless network communications over fairly short distances(a few metres) using radio or infrared signals.
Similar to LANs but there are no wires or cables.
Disadvantages
There may be problems of interference which can affect the signal.
The data transfer rate is slower than a wired LAN.
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.
WAN(Wide area network)
Wide area networks are often established with leased telecommunication circuits.
A wide area network is a telecommunications network or computer network that extends over a large geographical distance/place.
Wi-Fi
Refers to any system where it is possible to connect to a network through wireless communications.
Examples: 1.On the WLAN described above 2.PDAs and other handheld devices 3.Laptop computers which are WiFi enabled.
Tree Network
Facts
Has a central line(like a bus network) connecting together a series of 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.
All of the disadvantage and advantage of tree networks are same like bus and star networks.
Bluetooth
Facts
Radio waves (spread spectrum transmission) are used to provide links between mobile phones,computers and handheld devices and allow connection to the internet.
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).
Example of a wireless personal area networking (WPAN) technology.