OT: Re: How does gigabit ethernet work?

From: Arfon Gryffydd <arfonrg_at_texas.net>
Date: Thu Feb 11 10:32:51 1999

>> Let me push the question a bit more....
>> -How do they squeeze that much data down the line? Fiber-optics cabling
>> only? Data multiplexing?
>
>What about trying to think ? How do they squeze some 160+ MBit, as needed
>for a simple TV chanel within a cable (~512x625x25x16) - and they put not
>only one one, but rather some dozends of _uncompressed_ chanels within one
>cable, one simple copper cable as installed in hundreds of million places
>and they do it since 40+ years .... much data come on - if you would ask
>for 1,000 GBit connections maybe :)

        Well, within a cable signal, it's analog (you can therefore relate that to
a parallel digital signal), it's also multiplex using different frequencies...
        So, I assume that the answer is, gigabit ethernet uses some local
oscillators and modulates a butt-ton of frequencies using many parallel
bits. That would be the closest correlation to how cable TV works.

>> -How do they discriminate the beginning of one packet from the end of
>> another when running at such high speeds?

        Well, I was assuming that gigabit ethernet was a single serial connection
and that the packet header detector has to operate at frequencies several
multiples faster than the incomming data stream to detect new packets then
send a complete packet to a processor for address resolution. But, I take
it this is not the case. So, how do they do it?

>
>How can they seperate even a single Byte from each other at the ridicoulous
>speed of 300 Bd - even more, how they seperate two bits ?
>
>C'me on - it's the same water than ever - and it boils still at the same
>pressure/temperature combination.
>
>Gruss
>H.
>
>
>--
>Ich denke, also bin ich, also gut
>HRK
>
>
Received on Thu Feb 11 1999 - 10:32:51 GMT

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