Why are DSL uploads slower than downloads? Does it have something to do with the infrastructure or system architecture or is it managed that way? If managed that way, how does it benefit the ISP?

Thanks,
Sixto
87 300D

ISP's throttle upstream bandwidth because under most circumstances you don't need a large upstream pipeline...and its not limited by DSL.

ISP's benefit by preserving bandwidth.

It has something to do with data buffers needing to be filled up before being transmitted. If there aren't many uploads goin on, there are fewer packets of data being sent over the link, so it seems slow due to the delay between bursts. It can actually get faster the busier it gets.

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DSL may not be slower for uploading. SDSL is the same speed both ways. The first "S" is for "Symmetric." Contrast with ADSL, for "Asymmetric," specifically meaning that the upload speed differs from the download speed. There's also IDSL, for "ISDN DSL" but I don't know if anyone sells that these days.

You can buy symmetric links, but they are sold at business rates. I can almost guarantee that the business rate is a lot more than you're paying now for your current service, much less an increased tier.

Its not really "slower" its just capped at a lower potential maximum speed. The average home user doesn't need nearly as much outbound bandwidth as they do inbound. For instance....I have DSL running at 5Mbit inbound and 1Mbit outbound. If I pay more, I can get them to raise that to 8.5Mbit inbound and about 2-2.5Mbit outbound.

Outbound speed is most important when uploading lots of data, or using a VPN for heavy file transfers/connections, or running web/game servers....I run a server over my DSL, and the 1Mbit...(100k or so) is generally plenty.

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Thanks for the responses.

I should have been specific - our home service is stated to have an upload rate about a quarter of the download rate. What I meant to ask is whether ADSL and SDSL use different systems or just different rules applied to similar infrastructure.

Sixto
87 300D

I am pretty sure that they are similar interfaces, but increasing the upload rate means decreasing the download rate.