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Different types of Internet connections

The options for providing user connectivity to the Internet are given below:

1. Terminal Dialup/Modem (Shell connection)



    • Most common option
    •  User requirements limited to modem and communications software



  • Text-only access

 



  • Shell accounts were more popular before the advent of the Web. A shell account lets you use your computer much as if it were a virtual console associated with a remote computer. You can type commands, which are interpreted by the remote computer, and view the resulting output on your computer. Although a few web browsers, such as Lynx, can operate via a shell account, they don’t generally support the highly graphical, multimedia pages which web surfers have come to expect.

 

2. SLIP (Serial Line Internet Protocol)



    • Computer is treated as though it were directly connected for the period it is online
    •  Utilizes telephone lines



  • User must have modem, TCP software, SLIP software, & software for Internet applications

 



  • Multimedia access

 

3. PPP (Point-to-Point Protocol)



    • Computer is treated as though it were directly connected for the period it is online



  • Utilizes telephone lines
  •  User must have modem, TCP software, PPP software, & software for Internet applications
  •  Multimedia access
  •  While your computer is connected to the Internet, you can use it to surf the
    Web with your favorite browser. If your ISP allows, you can even run a
    web server, providing pages that can be viewed by others around the
    world.

 

4. ISDN (Integrated Services Digital Network)



    • Most often used to connect remote telecommuters to office LANs



  • Requires ISDN phone line access
  •  Faster than analog terminal dialup/modem service

 



  • User must have ISDN phone line, ISDN card, communications software,
    TCP software & SLIP or PPP software multimedia connectivity

 

5. DIAS



  • The DIAS offers a wire-line solution for high speed symmetrical Internet
    access on the existing telephone lines. It provides an “always on” internet
    access that is permanently available at customer’s premises. DIAS
    combines voice and internet data packets on a single twisted pair wire at
    subscriber premises that means you can use telephone and surf internet at
    the same time.

6. Cable Modem



    • The term “Cable Modem” is quite new and refers to a modem that operates over the ordinary cable TV network cables. Basically you just connect the Cable Modem to the TV outlet for your cable TV, and the cable TV operator connects a Cable Modem Termination System (CMTS) in his end (the Head-End).



  • Actually the term “Cable Modem” is a bit misleading, as a Cable Modem works more like a Local Area Network (LAN) interface than as a modem.

 



  • In a cable TV system, signals from the various channels are each given a 6-MHz slice of the cable’s available bandwidth and then sent down the cable to your house. When a cable company offers Internet access over the cable, Internet information can use the same cables because the cable modem system puts downstream data – data sent from the Internet to an individual computer – into a 6-MHz channel. On the cable, the data looks just like a TV channel. So Internet downstream data takes up the same amount of cable space as any single channel of programming. Upstream data – information sent from an individual back to the Internet – requires even less of the cable’s bandwidth, just 2 MHz, since the assumption is that most people download far more information than they upload.
  •  Putting both upstream and downstream data on the cable television system requires two types of equipment: a cable modem on the customer end and a cable modem termination system (CMTS) at the cable provider’s end. Between these two types of equipment, all the computer networking, security and management of Internet access over cable television is put into place.

 

7. Digital Subscriber Line (DSL) connection.

 DSL is a very high-speed connection that uses the same wires as a regular telephone line.
 Here areare some advantages of DSL:

1. You can leave your Internet connection open and still use thephone line for voice calls.
2. The speed is much higher than a regular modem
3. DSL doesn’t necessarily require new wiring; it can use the phoneline you already have.
4. The company that offers DSL (e.g. BSNL) will usually provide themodem as part of the installation.

 But there are disadvantages:
1. A DSL connection works better when you are closer to theprovider’s central office.
2. The service is not available everywhere. Other types of DSL include:
1. Asymmetric DSL (ADSL) line – The connection is faster for receiving data than it is for sending data over the Internet
2. Very high bit-rate DSL (VDSL) – This is a fast connection, but works only over a short distance.
3. Symmetric DSL (SDSL) – This connection, used mainly by small businesses, doesn’t allow you to use the phone at the same time, but the speed of receiving and sending data is the same.
4. Rate-adaptive DSL (RADSL) – This is a variation of ADSL, but the modem can adjust the speed of the connection depending on the length and quality of the line.

8. Direct Connection (Leased circuit)

 Most often used to connect sites within a specific organization; such as a university or business requires owning or leasing of cable (from 64 kbps to 1345 Mb) users typically connected via Ethernet LANs multimedia connectivity at its fastest.

9. Satellite connections

 This connection allows you to download Internet files via a satellite connection. This is an efficient method for receiving large Web graphics and other items, but you still need a modem connection for other features. You must purchase the connection hardware as well as subscribe to the service.

10. Wireless connections

 Pagers, cellular phones and personal digital assistants (PDAs) now allow varying levels of Internet access, from notification of E-mail to limited Web connections. Many of these services remain in the experimental stage.

The PPP connection is called as TCP/IP connection or PSTN dial-up connection. ISDN connection is called as ISDN dial-up connection. Cable Modem, DSL and Direct Connection are always-on connection.

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