Internet connectivity
- 2. As technology grows, so does our need for bigger, better and faster Internet connections. Over the years the way content is presented via the Web has also changed drastically. Ten years ago being able to center, bold, and produce text in different colors on a webpage was something to admire. Today, Flash, animations, online gaming, streaming video, database-driven websites, ecommerce and mobile applications (to name but a few) are standards.
- 3. There are various type of connectivity to get hook on to Internet. They all can be broadly classified into following category. Gateway Access Dial-up Connection Leased Connection DSL Cable Modem Connection VSAT
- 4. Gateway Access is also known as Level-One connection. It is the access to the Internet from a network, which is not on the Internet. The gateway allows the two different types of networks to “talk” to each other. But the users of the Gateway Internet have limited access to the Internet. They might not be able to use all the tools available on Internet. The local Internet Service Provider (ISP) normally defines this limitation. eg : VSNL (Videsh Sanchar Nigam Limited). All access to Internet from India are through VSNL gateway.
- 5. ‘Dial-up’ connection is also known as Level Two connection. This provides connection to Internet through a dial-up terminal connection. The computer, which provides Internet access is known as ‘Host’ and the computer that receives the access, is ‘Client’ or ‘Terminal’.
- 7. The client computer uses modem to access a “host” and acts as if it is a terminal directly connected to that host. This type of connection is also known as ‘Remote Modem Access’ connection. In dial-up connection to Internet, Host carries all the command that are typed on a client machine and forward them to Internet. It also receives the data or information from the Internet on behalf of the ‘Client’ and passes it to them. The client computer acts as a ‘dumb’ terminal connected to remote host. Dial-up connection uses either of the following protocols: Serial Line Internet Protocol (SLIP) Point to Point Protocol (PPP)
- 8. This type of connection can further be divided into three categories. Shell Connection In this type of Internet Connection, the user will get only textual matter of a Web Page. This connection does not support Graphics display. Shell Accounts were the only type of Internet access available for many years before the Internet entered in to the world of graphics and became more users friendly. TCP/IP Connection Today’s graphical World Wide Web browsers provide easier access with multimedia sound and pictures. TCP/IP can display both text and graphics. ISDN ISDN (Integrated Services Digital Network) offers Internet connectivity at speeds of up to 128 Kbps through the use of digital phone lines. ISDN is a dial-up service that has been provided by telephone companies for many years.
- 9. Leased connection is also known as direct Internet access or Level Three connection. It is the secure, dedicated and most expensive, level of Internet connection. With leased connection, your computer is dedicatedly and directly connected to the Internet using highspeed transmission lines. It is on- line twenty-four hours a day, seven days a week.
- 10. Digital Subscriber Line (DSL) is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line (ADSL), the most commonly installed DSL technology. DSL service is delivered simultaneously with wired telephone service on the same telephone line. This is possible because DSL uses higher frequency bands for data separated by filtering. On the customer premises, a DSL filter on each outlet removes the high frequency interference, to enable simultaneous use of the telephone and data.
- 11. Following are the several versions of DSL technique available today: Asymmetric DSL (ADSL) Symmetric DSL (SDSL) High bit-rate DSL (HDSL) Rate adaptive DSL (RDSL) Very high bit-rate DSL (VDSL) ISDN DSL (IDSL)
- 12. ADSL - Asymmetric Digital Subscriber Line ADSL is the short for asymmetric digital subscriber line ADSL supports data rates of from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and from 16 to 640 Kbps when sending data (known as the upstream rate). ADSL requires a special ADSL modem. ADSL+2 - ADSL Extension ADSL2+ service is most commonly offered in highly-populated metropolitan areas and subscribers must be in close geographical locations to the provider's central office to receive ADSL2+ service.
- 13. SDSL - Symmetric Digital Subscriber Line Short for symmetric digital subscriber line, SDSL is a technology that allows more data to be sent over existing copper telephone lines (POTS). SDSL supports data rates up to 3 Mbps. SDSL works by sending digital pulses in the high-frequency area of telephone wires and cannot operate simultaneously with voice connections over the same wires. SDSL requires a special SDSL modem. SDSL is called symmetric because it supports the same data rates for upstream and downstream traffic. VDSL - Very High DSL Very High DSL (VDSL) is a DSL technology that offers fast data rates over relatively short distances — the shorter the distance, the faster the connection rate.
- 14. Advantages: • Security: Unlike cable modems, each subscriber can be configured so that it will not be on the same network. In some cable modem networks, other computers on the cable modem network are left visibly vulnerable and are easily susceptible to break in as well as data destruction. • Integration: DSL will easily interface with ATM and WAN technology. • High bandwidth • Cheap line charges from the phone company. • Good for “bursty” traffic patterns Disadvantages • No current standardization: A person moving from one area to another might find that their DSL modem is just another paperweight. Customers may have to buy new equipment to simply change ISPs. • Expensive • Distance Dependence: The farther you live from the DSLAM (DSL Access Multiplexer), the lower the data rate. The longest run lengths are 18,000 feet, or a little over 3 miles.
- 15. A cable modem is a type of Network Bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high bandwidth of a HFC and RFoG network. They are commonly deployed in Australia, Europe, Asia and Americas.
- 16. Short for very small aperture terminal, an earthbound station used in satellite communications of data, voice and video signals, excluding broadcast television. A VSAT consists of two parts, a transceiver that is placed outdoors in direct line of sight to the satellite and a device that is placed indoors to interface the transceiver with the end user’s communications device, such as a PC. The transceiver receives or sends a signal to a satellite transponder in the sky. The satellite sends and receives signals from a ground station computer that acts as a hub for the system. Each end user is interconnected with the hub station via the satellite, forming a star topology. The hub controls the entire operation of the network. For one end user to communicate with another, each transmission has to first go to the hub station that then retransmits it via the satellite to the other end user’s VSAT.
- 17. Advantages Satellite communication systems have some advantages that can be exploited for the provision of connectivity. These are: • Costs Insensitive to Distance • Single Platform service delivery (one-stop-shop) • Flexibility • Upgradeable •Low incremental costs per unit. Disadvantages However like all systems there are disadvantages also. Some of these are • High start-up costs (hubs and basic elements must be in place before the services can be provided) • Higher than normal risk profiles • Severe regulatory restrictions imposed by countries that prevent VSAT networks and solutions from reaching critical mass and therefore profitability • Some service quality limitations such the high signal delays (latency) • Natural availability limits that cannot be mitigated against • Lack of skills required in the developing world to design, install and maintain satellite communication systems adequately
- 18. Wireless Internet Connection makes use of radio frequency bands to connect to the internet and offers a very high speed. The wireless internet connection can be obtained by either WiFi or Bluetooth.
- 19. Satellite Internet connection offers high speed connection to the internet. There are two types of satellite internet connection: one way connection or two way connection. In one way connection, we can only download data but if we want to upload, we need a dialup access through ISP over telephone line. In two way connection, we can download and upload the data by the satellite. It does not require any dialup connection.
- 20. Internet access is ability of individuals and organizations to connect to the Internet using computer terminals, computers, mobile devices; and to access services such as email and the World Wide Web. Various technologies, at a wide range of speeds have been used by Internet service providers (ISPs) to provide this service. Internet connection options vary by Internet Service Provider and by region. Technology changes at a rapid pace and so do Internet connection speeds.