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Why Can't ADSL Be Reversed?
John Macdonald asks: "An ADSL connection uses the asymmetric (that's the A in ADSL) bandwidth to provide much larger download than upload capacity. That's great for many situations, where people browse and collect, importing data far more than they export to the world at large. But there are some sites that could use the asymmetry more effectively the other way - with a large upload capacity and small download. This would work well for ftp and web servers, for example. So, why don't telcos provide this inverse capability? Is the hardware more expensive to run the other way? Is there just too little demand? Has nobody thought of it before? I'd guess that there is small enough demand that they prefer to only offer a symmetric, higher-speed, but also higher-priced, connection for such sites."
This is absolutely WRONG!
Even though there are separate physical lines that each ADSL user would be using to connect back to the CO, the lines eventually get bundled together. So, while they are still "separated", the fact that they are close together means that there is alot of cross-talk between the different lines. Therefore, for it to work like it does all of the "loud" signals need to be on one end. You can't have the "loud" signals on both ends at the distances ADSL is designed to use. So, reverse ADSL may be possible at the current speeds, but only if EVERYONE used reverse ADSL. You really cannot mix the asymmetry for different lines connected through the same community.