said by redgrandam:A better question then is why are uploads so limited in speed then? Just to limit home servers?
There are technical reasons.. No commonly used data communication protocol is inherently full duplex. I must be forgetting something fundamental, because I know full duplex on a single link is possible (by subtracting the transmitted signal from the total measured on the receiver), some other factor makes it impractical. Whatever, it is never done.
Copper Ethernet gets around this by having extra wires, a pair for each direction, basically. DSL and Docsis get around this by frequency division multiplexing. Downloading on some frequencies, uploading on others. That means the provider has to make a decision about how to allocate upload and download bandwidth.
Here's a chart of how spectrum is allocated in DSL:
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en.wikipedia.org/wiki/As ··· plan.svgI believe that DSL could theoretically reverse the speed split pretty easily, but Docsis has other issues. Upload on Docsis is limited to the lowest frequencies due to power output of the modem--it would have to be much beefier, and expensive, to output enough power to make use of high frequency channels. Docsis has further problems with interference at some frequencies:
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Re: Cisco DPC3848 - Modem gatewayGPON, for FTTH, uses wavelength division multiplexing--different colours of light for upstream vs downstream, essentially. That relaxes the trade off a lot, it is a lot like copper Ethernet having wires dedicated for each direction. It still seems like there is some asymmetry in upstream and downstream data rates though.. Maybe somebody can add some details on this..
