| | Networks A network is a communication system which allows two or more computers and their peripheral devices to be connected. Network Notepad: Freeware for creating interactive network diagrams and FlowchartsNetwork Notepad is a Freeware program for creating interactive network diagrams. http://www.networknotepad.com/ Click Here free software for doing network designs, similar to Visiohttp://www.weresc.com/network.php
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| 1 | There are three basic network topologies: bus, ring and star. The fourth commonly used architecture is the tree which is really a hybrid of a star or bus network. Then there are hybrid variations of these and lastly the mesh topology which is mainly a product of the internet but which is also used in LANs where each of the workstations uses mission critical data. 
Ring topology is a LAN architecture in which all devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. In a ring topology network computers are connected by a single loop of cable, the data signals travel around the loop in one direction, passing through each computer. Ring topology is an active topology because each computer repeats (boosts) the signal before passing it on to the next computer. One method of transmitting data around a ring is called token passing. The token is passed from computer to computer until it gets to a computer that has data to send. If there is a line break, or if you are adding or removing a device anywhere in the ring this will bring down the network. In an effort to provide a solution to this problem, some network implementations (such as FDDI) support the use of a double-ring. If the primary ring breaks, or a device fails, the secondary ring can be used as a backup.  In BUS TOPOLOGIES, all computers are connected to a single cable or "trunk or backbone", by a transceiver either directly or by using a short drop cable. All ends of the cable must be terminated, that is plugged into a device such as a computer or terminator. This is to prevent the signal bouncing back. The number of computers on a bus network will affect network performance, since only one computer at a time can send data, the more computers you have on the network the more computers there will be waiting send data. A line break at any point along the trunk cable will result in total network failure.A break anywhere in the cable will usually cause the entire segment to be inoperable until the break is repaired. networks implement a bus topology. Computers on a bus only listen for data being sent they do not move data from one computer to the next, this is called passive topology. 
Star configuration: topology is a LAN architecture in which the endpoints on a network are connected to a common central hub, or switch, by dedicated links. The primary advantage of this type of network is reliability - if one "point-to-point" segments has a break, it will only affect the nodes on that link; other computer users on the network continue to operate as if that segment were non-existent. | 
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| 2 | When categorizing a network by size there are two main categories: - LANs (local area network) is network confined to a small geographic such as a building or a group of buildings within a small defined area.
- WANs (wide area network) is a network spread over a large dispersed geographic area where 2 or more LANs are networked together.
There are other categories of networks such as CANs and MANs. A CAN (campus area network) is a network within a university campus and can be seen as being the extreme end of a LAN. While it really too large to be called a LAN it is too small to be called a WAN. A MAN (metropolitan area network) is really at the extremely small end of WANs and in a sense is too small to be a true WAN. |
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| 3 | Network AddressingEach network will have an IP address granted by the ISP (internet Service Providor) and each machine on that network will also have address inside that network. The ip address will be listed in an ARP Table (address Resolution Protocol) which is a table that the router will use to send packages to machines. Press <WIN+R> to reach the command line At the prompt type
arp -a to see the arp table for that router. Blow is a screen dump showing the arp table egenrated by the above command. 
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| 5 | Examples of Networks
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