RE: Output Drops on Gig Interface

Hey Marko,

> -----Original Message-----
> Sent: Tuesday, May 04, 2010 2:16 PM
> To: Narbik Kocharians
> Cc: itguy.pro_at_gmail.com; Kambiz Agahian; naman sharma; Cisco certification
> Subject: Re: Output Drops on Gig Interface
>
> On Tue, May 4, 2010 at 17:39, Narbik Kocharians <narbikk_at_gmail.com> wrote:
> > That is true, the end that is in half Duplex mode should get "late
> > collisions" and the end that is in full duplex mode should get "CRC checks",
> > whereas, a mismatch in Speed (Which i don't think that could be the problem
> > that you are experiencing) should show as "NOTCONNECTED".
>
> Quite right, however, if duplex is not hardcoded, but speed is, it
> would not be negotiated in most cases. Cisco used to default to
> half-duplex in this case. I've seen quite a few issues caused by
> configuring only parts of the speed/duplex pair.
>
> If any of them is set manually, negotiation is disabled. To negotiate
> speed and duplex, both need to be set to auto.
>

It was my understanding that by default, all devices are supposed to perform autonegotiation as 802.3z does not specifically define a way to turn it off. Also, Cisco devices do not support half-duplex Gig and the standard does not have support for it either. With link negotiation turned off, the device with autonegotiation turned off will report up and the other side will be down.

I have not tested all of these scenario's in great detail, so in practice it might differ slightly.

-ryan

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Received on Tue May 04 2010 - 18:32:22 ART