Testing Ethernet Ports

Barney Wolff barney at databus.com
Thu Sep 1 15:27:19 GMT 2005

On Thu, Sep 01, 2005 at 09:58:14AM -0500, Will Maier wrote:
> On Thu, Sep 01, 2005 at 10:36:04AM -0400, Ames, Jonathan (N-ENSCO) wrote:
> > Can someone give me a hand with this?
> Here goes...
> > A PC has two ethernet ports, both directly on the motherboard.
> > Can I connect them externally with an ethernet cable and ping from
> > one port to the other to test them both?  How?
> Lemme see if I parsed your question correctly:
>     * box.A.nic.1 --cable--> box.A.nic.2
> Is that what you're talking about? Sure. Use a crossover cable,
> assign each interface a different IP on the same subnet (eg
> and and ping from one to the other:

I don't believe this will do what's wanted - the packets will not actually
go thru the NICs, as the OS is smart enough to realize that the dest is
internal.  With a crossover cable (not required with gigabit nics) you
can't tell, so if you try it use a switch and look at the lights.

Barney Wolff         http://www.databus.com/bwresume.pdf
I never met a computer I didn't like.

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