Why different upload/download speeds?

It just dawned on my that my new Covad account has an upload speed of 128k and a download speed of a thousand-and-something k.

There's got to be a business reason, but what?

Reply to
(Pete Cresswell)
Loading thread data ...

It is in the design of the ADSL protocols. The theory was that most users would want more download speed. If the protocol allowed more upload, that would reduce the capacity of the line for download speed.

The SDSL protocol has the same speed in both directions. But the download speed is typically lower than for ADSL.

Reply to
Neil W Rickert

Hi Pete,

Its to do with the signaling technology employed for ADSL. The general idea is that Home users will want to download more data faster than they will want to upload, so the service is "Asymmetric" in that regard, big download bandwidth and small upload bandwidth as the user sees it.

Now it just so happens that this also fits well with transmission line theory that is present with the physical wiring of telephone exchanges (the CO buildings in North American speak). There is a great density of Copper going into ONE building, so the chance of "cross-talk" or interference between the copper pairs is much higher at the exchange, while each Home end has only a small amount of copper so cross-talk is low. That means it is easier to "read" a weak signal at the Home, than it is to "read" the same signal at the exchange building. If the signal heading into the exchange is only low speed (relative to the outbound signal), its easier to read than a high speed signal.

If you want equal speed connections, then you need an SDSL service, where both directions are the same speed or are symmetrical. Needless to say, many providers don't like doing SDSL because they can't put too many SDSL services in one copper cable, they end up swamping each other out...


Reply to

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.