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Internet Access Guide

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Internet Access Guide : ADSL

Full Rate ADSL maximum downstream rate is 8 Mbps and upstream rate is 1 Mbps. ADSL Lite maximum downstream rate is 1.5 Mbps and upstream rate is 512 kbps. The real-world performance (rate) depends on the distance from the DSLAM (at the Central Office or in a neighborhood access node) to the subscriber site, the telephone line condition, connection to backbone network, and Internet traffic load. An ISP usually offers ADSL connection service in several performance (downstream and upstream rates) levels to make it easier for its subscribers to choose rates that fit their needs.

You don't have to buy an ADSL modem because the ISP usually provides an ADSL modem for free as part of your subscription plan or for a fixed monthly rental fee. But if you think it is cheaper to buy than to rent an ADSL modem or if you need an ADSL modem with additional requirement, you can buy it at almost any computer or electronics retailer.

Internet access over ADSL is an always-on connection, that's every time you turn on your computer you are connected to the Internet without dialing a number and logging in to the ISP. However, nowadays most ISPs offer a type of ADSL connection that requires log-in such as in dial-up Internet access. This is implemented using PPPoE or PPPoA. The purpose of applying a user log-in technique is to ensure the ADSL connection security using a point-to-point link and to enable traffic metering. ADSL Internet subscription fee is mostly a flat monthly rate but it may also be charged based on the number of bytes downloaded and uploaded or connection time.

Internet Access over ADSL
User Equipment ADSL modem, splitter, Ethernet card (if the ADSL modem connects through Ethernet port)
Operator Equipment DSLAM
Modem Standard G.dmt (G.992.1), G.lite (G.992.2)
Maximum Downstream Data Rate 8 Mbps (Full Rate), 1.5 Mbps (G.Lite)
Maximum Upstream Data Rate 1 Mbps (Full Rate), 512 kbps (G.Lite)
Connection always-on; log-in (PPPoE/PPPoA)
Charging Flat monthly rate plus (optional) ADSL modem rental fee or usage-based (transferred bytes / connection time).
Simultaneous Service Telephone (lifeline POTS)

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