Thursday, March 29, 2007

10 Gigabit Ethernet "Crossover"

I just saw this article comparing Fibre Channel, 10Gb Ethernet, and InfiniBand, and I thought it was interesting.

It points out information from the Dell'Oro consulting firm showing Gigabit Ethernet ports first outshipped Fast Ethernet ports in 2004, some seven years after GigE was introduced, and five years after the 1000BASE-T spec was introduced in 1999. (There is a good article here on the 1000BASE-T PHY.)

So if it took five years from the 1000Base-T release until 1000BASE-T ports exceeded 100BASE-T ports, despite backwards compatibility.

"Crossover", as this point is known, is very important in for a new replacement technology. Once a new standard or product reaches crossover, the second half of market penetration typically occurs quickly. Backwards compatibility helps, but realize a compatible 100/1000BASE-T port does not mean a switch blade with 48 of those ports will be compatible with an older blade chassis. Also, the increased cost of the new technology causes some resistance.

Today, there is a much bigger challenge for 10GBASE-T: Power consumption. From the article on the 1000BASE-T PHY I linked to earlier:

"Because of the complexity of the signal-processing task, a 10/100/1000Base-T copper PHY is the dominant consumer of power in essentially all gigabit switch designs supporting copper media. First-generation 1000Base-T copper PHYs introduced in 1999 in 0.35-micron CMOS consumed well over 5 watts of power-too high for widespread use in high-density Gigabit Ethernet switch form factors."
With 10GBASE-T, the power required is much higher. Chelsio's new 10GBASE-T NIC requires 24 watts of power, and can only drive a signal over 50 meters of the 100 meter distance of the 10GBASE-T spec. Now some of the NICs power is the supporting TCP Offload Engine (TOE) and other circuitry. But it is probably safe to say 15 watts for each 10GBASE-T switch or NIC port is currently required.

So while some say the promise of consolidated I/O will drive the transition from Gigabit Ethernet to 10 Gigabit Ethernet faster than the transition from Fast Ethernet to Gigabit Ethernet, power consumption will likely slow this transition significantly.

So indeed the transition from Gigabit Ethernet to 10 Gigabit Ethernet may follow the transition from Fast Ethernet to Gigabit Ethernet. In that case, if 1000BASE-T is a gauge, and the 10GBASE-T spec was just approved in 2006, it could take until 2011 before 10GBASE-T ports outnumber 1000BASE-T ports.

What is good about this is the software (iWARP, iSER, NFSoRDMA, pNFSoRDMA, etc.) and supporting networking protocols for this new generation of Ethernet will have plenty of time to catch up. This means once crossover does happen, it should have a very strong impact on the market.

Meanwhile, it appears there continues to be plenty of opportunity for Fibre Channel for storage and InfiniBand for low-latency IPC.

Related posts:
Predictions for the future of low-latency computing, it's not where you think it is
Part 1 | Part 2 | Part 3

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