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Originally Posted by kustard
Yeah. Upload speeds are annoyingly slow here. What most people may not realise is that for every bit of data you download there is some form of data upload, most often ACK/NAK transactions for file transfers.
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TCP doesn't do NAKs, only ACKs.
The upload speed doesn't matter much if you are only downloading.
Read Stevens "TCP Illustrated: Volume 1". Run wireshark for a while and see what traffic a single download generates. There is an exponential backoff in ACK packets until it can reach one ACK per window (probably 64K bytes). That's one 40 byte packet up for multiple 1492 byte packets (assuming LLC/SNAP encapsulation) down. Selective ACK can reduce that even further.
Unless of course you get lost packets when duplicate ACKs trigger retransmissions. The protocol aims to minimise the number of retransmissions and stop the pipe from draining.
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We host our own servers here at work and have to pat extra to get a fast upload speed which really sucks.
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Now that does require upload bandwidth, and you will pay a lot more for SDSL. At least it's a deductable business expense.