Monday, October 9, 2000		On Hardware

LAN administrator — server’s sentry
By Vipul Verma

Networking is the lifeline of the computer world. No networking, no IT revolution. While working on a computer, no matter wherever the work is done and whatever is done, it is most likely to be a part of some network.

The Internet itself is a big network scattered across the globe to which millions of computers are linked. Whenever you connect to the Net, you actually join a network of computers to upload/download information from it. Clearly, today computer means a network.

Basically, networking means connecting two or more computers in such a way that the resources of all computers are available to each other without losing the properties as a standalone computer. As the first step, it is essential for network to have more than two computers to connect. Now, the method to connect these computers could be same in all cases.

In case of two computers, you can use several software in place of a normal system of using LAN.

For connecting two computers to each other, there are two methods.

1) Direct cable connection

2) Dial-up networking

Under the direct cable connection, a connection is established between two computers, either by serial port to serial port, or parallel-to-parallel port. By enabling sharing on the resources of your computer, you can create a network between two computers. The resources here refer to the hard disk, including partition, CD-ROM and floppy disk. You can enable sharing on all these resources by clicking right mouse button on their icon and then enabling sharing in the sharing sub-menu.

However, if you do not have direct cable connection installed on the computer, then it will have to be installed from the add/ remove program> Windows set up, Tab in control panel. (It should be noted that there could be some changes in the procedure and terminology of various versions of Windows and this article has been written on the basis of Windows95/97.)

For direct cable networking, no specialised software is required as it is in-built in Windows. However for dial-up networking, if you do not have Hyper Terminal, software like PC anywhere, Remotely anywhere and Reach out may be required.

We have discussed dial-up networking and also this software in the previous issues. So, for making a network using this software, you need a telephone line and a modem. Once two computers are connected, you cannot only share the resources, but can also actually control it from any remote place.

However, dial-up networking has certain limitations. For example, you get low bandwidth in dial-up connections using normal telephone lines; thus the actual data transfer rate is very slow. Moreover, the cost associated with it is also high. Therefore for occasional networking requirement, this may prove useful, but or regular networking requirements, it may not be the viable option.

For all kind of networking requirements, LAN is the universally accepted best option. The Local Area Network, more popularly known as LAN, is actually a high-speed network of computers, which is a fault-tolerant data network and covers a relatively small area. Typically, local area networks are installed to connect personal computers, workstations, servers, peripherals like printers and modem. Using LAN, a person can have shared access to the resources available on the network and can use the devices and applications. Using a LAN, all connected computers can interchange files and also e-mails. Using a LAN, you can also share the Internet connection with other computers on LAN, with a single modem, telephone line and the Internet connection.

Since, LAN is a hardware-related terms, so for installing it you require LAN cards or the Ethernet cards, repeaters, hubs, LAN extenders, bridges, LAN switches, and routers. The LAN cards are attached on the motherboard of the computer in the PCI slot and have the capacity to transfer data at a blistering speed.

A repeater is referred to a physical layer device used to interconnect the media segments of an extended network whereas a hub is a physical-layer device that connects multiple user stations, each via a dedicated cable. A LAN extender is referred to a remote-access multilayer switch that connects to a host router.

Normally, LAN servers are put for the purpose of installing a LAN system and all computers are connected to the server. The computers, which are connected to the LAN servers, are called nodes and they also perform the function of stand-alone computers. Thus, the users who need an application quite frequently can download it once from the server and then run it from their local hard disk. Users can also order printing and other services as needed through applications run on LAN server.

A user can share files with others at the LAN server; though the rights related to the read and write access is being maintained by a LAN administrator. Thus, LAN administrator may provide access to a specific part of the server to particular notes only and at the same time may restrict the access to others. This is one of the biggest advantages of LAN, besides networking. The information can be channelised yet controlled depending upon its criticality.

For example, if the data related to accounts is on the LAN server, it would be required by the accounts department and some other departments like audit. In this case, the marketing and sales department is not concerned with the accounts data, thus their access could be restricted to the accounts data. Similarly, the accounts people have not much to do with data related to sales and marketing, thus their access could be restricted to that extent. In a way, channelisation of data this way can prove to be very helpful and effective.

The LAN servers can also be used for the Internet-based applications as a Web server. However, this is sometimes risky because, the hackers on the Internet can substantially cause damage, if they manage to break into a company’s Web servers. If proper safe guards, like the use of Firewalls are taken to secure internal applications and data from outside access, then even a LAN server can efficiently work as a Web server.

For putting up a LAN system, there are many types of networking technologies like Ethernet, token ring, attached resource computer network, fibre distributed-data interface. Similarly, there are three major LAN transmission methods, which can be classified as unicast, multicast, and broadcast. In each type of transmission, a single packet is sent to one or more nodes. Normally, in a unicast transmission, a single packet is sent from the server to the node on a network.

As the first step, the server addresses the packet by using the address of the node. The package is then sent onto the network, and finally, the network passes the packet to that particular node.

In the multicast transmission, a single data packet is copied and sent to specific nodes on the network.

First, the server sends the packet by using a multicast address. The packet is then sent into the network, which makes copies of the packet and sends a copy to each node that is part of the multicast address, whereas in a broadcast transmission a single data packet that is being copied and sent to all nodes on the network. In these types of transmissions, the server sends the packet by using the broadcast address. The packet is then sent into the network, which makes copies of the packet and sends a copy to every node on the network.