依照文中的資訊向 Google 求教得來的相關資料，提供各位大大參考~

感覺 ADSL2/ADSL2+ 用了更多的技術在裡面...

ADSL2 AND ADSL2plus - THE NEW ADSL STANDARDS (From: DSL Forum 的白皮書)
http://www.dslforum.org/aboutdsl/ADSL2_wp.pdf


ITU-T Study Group 15 - Table of Draft New/Revised Recommendations under AAP (From: ITU)
http://www.itu.int/ITU-T/studygroup...le-sg15aap.html





ADSL2 (ITU G.992.3 and G.992.4) adds new features and functionality targeted at improving performance and interoperability, and adds support for new applications, services and deployment scenarios. Among the changes are improvements in data rate and reach performance, rate adaptation, diagnostics and stand-by mode, to name a few.



ADSL2plus (ITU G.992.5) doubles the bandwidth used for downstream data transmission, effectively doubling the maximum downstream data rates, and achieving rates of 20 Mbps on phone lines as long at 5,000 feet. ADSL2plus solutions will most commonly be multimodal, interoperating with ADSL and ADSL2, as well as with ADSL2plus chipsets. More detail about ADSL2plus is included later in this paper.