Friday, June 20, 2008

Computer & network

Computer & network
A computer network is an interconnection of a group of computers. Networks may be classified by what is called the network layer at which they operate according to basic reference models considered as standards in the industry such as the four-layer Internet Protocol Suite model. While the seven-layer Open Systems Interconnection (OSI) reference model is better known in academia, the majority of networks use the Internet Protocol Suite (IP) as their network model.

By scale

Computer networks may be classified according to the scale: Personal area network (PAN), Local Area Network (LAN), Campus Area Network (CAN), Metropolitan area network (MAN), or Wide area network (WAN). As Ethernet increasingly is the standard interface to networks, these distinctions are more important to the network administrator than the end user. Network administrators may have to tune the network, based on delay that derives from distance, to achieve the desired Quality of Service (QoS). The primary difference in the networks is the size. Controller Area Networks are a special niche, as in control of a vehicle's engine, a boat's electronics, or a set of factory robots.

By connection method

Computer networks can also be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fiber, Ethernet, Wireless LAN, HomePNA, or Power line communication. Ethernets use physical wiring to

connect devices. Often, they employ the use of hubs, switches, bridges, and routers.

Wireless LAN technology is built to connect devices without wiring. These devices use a radio frequency to connect.

Home and Small Office computer Networking

If you have two or more computers and a wired/wireless router, you can easily set up a network that will allow you to do things like print wirelessly from your laptop to a printer hooked up to your network (the printer can be connected to another computer or a print hub). You can also access and transfer files from computer to computer. Personally, I find wireless networking really useful on my laptop. My laptop can still print and access data on my desktop anywhere in my home. Below is an example of a home network consisting of both wired and wireless computers.

There are five things you must do to each computer that will be on the network:

1. Give each computer on your network a unique name.

2. Set the Workgroup of each computer on your network to the same name (the Workgroup name can be anything but it has to be the same on all computers on your network). The Workgroup name is the name of your network.

3. Enable File and Printer Sharing.

4. Configure your firewall to allow File and Print Sharing.

5. Once File Sharing has been activated you can share files within a given folder by right clicking on the folder and then select “Sharing and Security...”. Then put a check in the box “Share this folder on the network” and optionally “Allow network users to change my files.”

The first 3 tasks can be accomplished with the Network Setup Wizard in Windows XP and the Network and Sharing Center in Windows Vista. The Network Setup Wizard is located in the control panel. Here are videos on using the Network Setup Wizard in Windows XP and in Windows Vista. In Windows 2000 you have to do this manually (Start->Setting->Control Panel->System->Network Identification->Properties).

For some online applications it may be useful to edit the settings on your router so that static DHCP is enabled for each computer on your network. Setting up static DHCP for each computer will allow port forwarding to work. In general, port forwarding will be required for all application that allow remote computers to connect to your computer. Editing settings on your router is done by typing your routers IP address into your web browser's address field