10Gbase-T doesn't make much sense for a new virtual environment. Once you factor in the cost of the cabling and power, you probably would have been better off with DAC or FET interconnects. Also 10Gbase-T does not necessarily work with Legacy wiring, depending upon how it was run. Large bundles of wire cause crosstalk issues on legacy cabling, this is the reason for large jackets on 6A. http://www.siemon.com/us/learning/alien-crosstalk-guide.asp I'm not saying it won't work for your scenario as I am not familiar with your environment, just keep it in mind that with most environments, DAC is a cheaper and provides better latency for your storage traffic. -----Original Message----- From: Jima [mailto:nanog@jima.tk] Sent: Monday, October 01, 2012 3:33 PM To: nanog@nanog.org Subject: Re: So what's the deal with 10Gbase-T Gotcha. With SFP+ I think the only nod to backward compatibility would be 1gbit RJ-45 SFPs, which can get a little spendy in large numbers (although so can DACs). As for distance, I admit I haven't encountered any DACs longer than 15 meters (~49 feet) -- not that I'm positive they don't exist. Jima On Mon, Oct 1, 2012 at 2:10pm, Andreas Echavez wrote:

Mostly backwards compatibility; simplicity. We're planning for some super-high-density virtualization/storage projects mixed in with lower bandwidth gear, and sticking to one type of cable for everything would be convenient. I thought DAC had some distance limitations as well.

This is all speculation though, I don't have any personal experience with the 10Gbase-T stuff either. I have no idea what to expect performance-wise.

-A

On Mon, Oct 1, 2012 at 12:58 PM, Jima <nanog@jima.tk> wrote:

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Does anyone here have experience running copper 10Gbase-T networks? It seems like the standard just died out. For us it would make a lot of sense for our applications -- even if throughput and latency aren't as great. If anyone out there knows of any *copper* 10 gig-t switches (48 port?), I'd be interested to hear your experiences. I can't seem to find any high-density ones from major vendors.

Is there something unique about your environment that wouldn't allow you to use 10gbit SFP+-based switches with DAC (Direct Attach Copper) cables? Those seem fairly well supported.

Jima

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