There are several ways to connect to the Internet. the more expensive services provide more features, more flexibility, and greater data transfer capacity. larger companies choose dedicated internet access or LAN dial-up. Smaller organizations are happy with PC dial-up access and terminal emulation, which provides E-mail and other services through a service provider’s computer.
Dial-up and Terminal Emulation
This is the simplest and cheapest type of connection to the Internet. all you need is a computer with a modem (attached to a phone line) and any of the popular telecommunications packages. Windows XP and other OS have bulletin facilities. the individual user dials into an internet service provider. each user has an account on the provider’s internet services host computer to the Internet. the given below image shows this facility through VSNL in India.
When you use PC dial-up (also called a terminal account), your computer runs a terminal emulation program to communicate with the service provider’s host computer, and you ask the host computer to go out onto the internet to do what you want to be done. Most host providers will send and receive an e-mail, transfer files from a remote Internet computer to the host which you can then download to your local computer, and provide access to USENET (the typical bulletin boards/newspaper/discussion groups on the Internet).
Many internet access providers also allow dial-up users to interactively roam the internet in real-time logging on to remote hosts with TELNET, searching indexed databases with WAIS, and locating esoteric information with Gopher. the equipment and software for PC dial-up are essentially the same whether the user is dialing from a stand-alone computer at home, from a networked computer equipped with a local modem, or from a networked computer using a communications server and a shared pool of network modems.
The computer uses terminal emulation software, and not TCP/IP to talk to the Internet host computer. the internet host computer uses TCP/IP to talk to the rest of the internet. Ordinary modems and telephone lines provide adequate throughput for PC dial-up access, though fast modems make the experience more pleasant.
Dedicated Internet Access
The most popular Internet access for companies and institutions is a dedicated phone line connecting your LAN to the Internet 24 hours a day. However, dedicated internet access requires a substantial initial investment in equipment. the main continuing cost is a flat monthly fee for the use of the line. it varies with line capacity, and line capacity determines how many users can connect to the internet simultaneously.
An inexpensive modem-based connection, which is set up only when it is needed, is the ideal solution for occasional use on the Internet. running a Web server, handling a large volume of mail, connecting an entire network of users, or, offering other information services require a permanent connection to the Internet and higher bandwidth than a normal modem can deliver. the solution is a leased line connection to the internet which is fast and permanent. depending on your bandwidth requirements ISPs can provide leased lines ranging from 24 kbps to 2 Mbps or more.
The minimum requirement for accessing the Terminal account is Windows 9. X machines or higher versions running on P4. A P2 processor machine with an adequate hard disk and 28.8 Kbps error-correcting modem server is enough for a good connection in India.
The minimum requirement for accessing a TCP/IP account, which requires graphics capability, is a P2 processor machine with 128MB (preferably 256MB) RAM, or one having similar processor power, such as an Apple MAC. at least a 28.8 Kbps modem is needed. for an IBM-compatible machine, either Windows 98, XP, or Windows 2000 server operating system is required for the TCP/IP account.
If you are using Windows 98 or XP system software, appropriate 16-bit TCP/IP stack software will be required. most of these have an auto-install program, which, during installation will ask for two IP addresses for the DNS service, one primary and one secondary. if you are also installing e-mail software such as Eudora, then one more IP address, for an SMTP server, needs to be entered.
For a TCP/IP account, in addition to the browser and e-mail applications, you may need software for other applications, like Telnet and FTP. Internet software such as “Chameleon” and “Internet in a Box“, usually, have many of these applications bundled in. application software packages for networking employ a design called client/server architecture, where the software sitting on the PC, i.e, your software packages, are optimized for ease-of-use and may be referred to as the “Client”. for Windows 9. X and XP, the TCP/IP stack software supplied with it has to be installed.
VSAT stands for Very Small Aperture Terminal. it can be described technically as an intelligent earth station connected to a geosynchronous satellite suitable for supporting a variety of two-way telecommunication and information services such as voice, data, and video.
These tiny terminals have 1-meter antennas and can put out about 1 watt of power. the uplink is generally good for 19.2 kbps, but the downlink is more, often 512 kbps. in many VSAT systems, the micro-stations do not have enough power to communicate directly with one another. instead, a special ground station, the hub, with a large high gain antenna is needed to relay traffic between VSATs as shown in the below image.
Hub equipment is the center of all activity during satellite communication among the various VSAT locations on the earth. it carries out health checks on all VSATs and undertakes all kinds of configurations for the VSAT at each station to introduce different types of multiple access techniques. it controls the traffic, depending on the user’s requirement in terms of bandwidth, and allocates resources.
the hub also monitors the VSATs. it carries out the billing. the hub located at NOIDA in U.P., owned and operated by HCL Comnet, works on an inbound of 192 kbps and outbound of 1024 kbps. the main function of the hub equipment is to receive inbounds and formulate outbounds.