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The Road To Terabit Ethernet
stinkymountain writes "Pre-standard 40 Gigabit and 100 Gigabit Ethernet products — server network interface cards, switch uplinks and switches — are expected to hit the market later this year. Standards-compliant products are expected to ship in the second half of next year, not long after the expected June 2010 ratification of the 802.3ba standard. Despite the global economic slowdown, global revenue for 10G fixed Ethernet switches doubled in 2008, according to Infonetics. There is pent-up demand for 40 Gigabit and 100 Gigabit Ethernet, says John D'Ambrosia, chair of the 802.3ba task force in the IEEE and a senior research scientist at Force10 Networks. 'There are a number of people already who are using link aggregation to try and create pipes of that capacity,' he says. 'It's not the cleanest way to do things...(but) people already need that capacity.' D'Ambrosia says even though 40/100G Ethernet products haven't arrived yet, he's already thinking ahead to terabit Ethernet standards and products by 2015. 'We are going to see a call for a higher speed much sooner than we saw the call for this generation' of 10/40/100G Ethernet, he says."
That's a bit hard to say. But here's a way of thinking about it:
The Shannon-Hartley theorem states that the channel capacity (e.g. the data bandwidth, measured in bits per second) is related to the channel bandwidth (measured in hertz). If we assume a very pessimistic signal to noise ratio of 1:1, the SH theorem says that the cable's bandwidth in hertz will be the same as the cable's bandwidth in bps.
So if we want a cable capable of transmitting information at 1tbps, the cable will need a bandwidth of roughly 1000 GHz. That means that it would be impossible to carry that amount of information using even microwaves. We're talking about at minimum infrared light. Or in other words -- we're talking about fiber optics, not cat5.