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| Please note that bandwidths are approximate. Read a comparison between internet connections or return to the Download Time Calculator. |
What are the differences between various internet connections?
- Dialup is naturally the slowest type of connection to the Internet. It runs over analog telephone lines, and its speed is limited by the quality of these lines, which were designed for low-quality voice calls, not data transmissions. Dialup relies on modems (modulator-demodulators), which max out at 57600 bps (in practice, 53000 bps).
- ISDN (Integrated Services Digital Network) is a digital connection over a conventional telephone line. It is not in common use, because it has been supplanted by DSL. ISDN offers speeds up to twice as fast as dialup.
- DSL, or digital subscriber line, sends signals on a higher frequency than voice signals over telephone lines. It offers high speeds, but bandwidth degrades as the length of the telephone line increases from the modem to the telephone company's central office. DSL connections are point-to-point - they are not shared in a neighbourhood. A DSL household has a dedicated connection to the telephone central office, which means if your neighbours are surfing, they will not slow you down.
DSL comes in two flavours:- ADSL - Asynchronous DSL means that uploading is much slower than downloading. Internet service providers (ISPs) adopt this technology so that they can spend less on bandwidth and so that they discourage users from running bandwidth-intensive servers.
- SDSL - Synchronous DSL provides equally fast upstream/downstream bandwidth. SDSL is expensive and generally used by businesses hosting web servers.
- Cable uses television coaxial cable to connect to the Internet. Cable has the potential to offer very high speeds, but is limited because cable is shared in a neighbourhood. If the aggregate bandwidth being used by customers exceeds the bandwidth of the physical cable connection in a neighbourhood, then slowdowns are observed.
- Satellite also comes in a couple of flavours:
- Modem-Satellite - A modem is used to send upstream data requests, while a dish receives data from a satellite. This method is plagued by latency, as it takes a long time for a request to travel via dial-up to the web server in question, and for the response to arrive through the satellite system.
- Satellite two-way - The satellite dish sends and receives data. This technology is more recent, but still suffers from latency problems, simply because satellites are far away.
- Corporations may use T1, T3, and above for hosting web servers, serving office users, and so forth. These lines are dedicated digital trunks, reliable, and fast, but prohibitively expensive for home users.