[c-nsp] disable NEXT(Near end crosstalk) cancellation on 1000BASE-T port in Catalyst or Nexus brand switch

[Gert Doering]

Hi,

On Fri, Oct 24, 2014 at 01:49:53PM +0300, Martin T wrote:
> according to Cisco documentation(for example
> http://www.cisco.com/c/en/us/td/docs/routers/access/interfaces/nm/hardware/installation/guide/conntge.pdf)
> 1000BASE-T ports can not be looped back through use of an external
> loopback cable. This should be because of NEXT cancellation
> implemented in 1000BASE-T phy. Is there a way to disable this on newer
> Catalyst or Nexus brand switches so that one could use RJ45 loopback
> cable on 1000BASE-T ports?

The main reason why this isn't working is that there are no "send" and
"receive" lines you could loop - everything is used bidirectionally.

gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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