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Date:      Mon, 11 Jul 2011 22:52:39 -0700
From:      Doug Barton <dougb@FreeBSD.org>
To:        Charles Sprickman <spork@bway.net>
Cc:        YongHyeon PYUN <pyunyh@gmail.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, David Christensen <davidch@broadcom.com>, David Christensen <davidch@freebsd.org>
Subject:   Re: bce packet loss
Message-ID:  <4E1BE127.9060200@FreeBSD.org>
In-Reply-To: <alpine.OSX.2.00.1107120143390.1070@freemac>
References:  <alpine.OSX.2.00.1107042113000.2407@freemac> <20110706201509.GA5559@michelle.cdnetworks.com> <alpine.OSX.2.00.1107070121060.2407@freemac> <20110707174233.GB8702@michelle.cdnetworks.com> <alpine.OSX.2.00.1107072129310.2407@freemac> <5D267A3F22FD854F8F48B3D2B523819385C32D96B7@IRVEXCHCCR01.corp.ad.broadcom.com> <alpine.OSX.2.00.1107082009350.1070@freemac> <5D267A3F22FD854F8F48B3D2B523819385F12FE86B@IRVEXCHCCR01.corp.ad.broadcom.com> <alpine.OSX.2.00.1107112234460.1070@freemac> <4E1BDD3F.4090607@FreeBSD.org> <alpine.OSX.2.00.1107120143390.1070@freemac>

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On 07/11/2011 22:47, Charles Sprickman wrote:
> On Mon, 11 Jul 2011, Doug Barton wrote:
> 
>> On 07/11/2011 21:09, Charles Sprickman wrote:
>>> I've had it hammered into my brain over the years that for servers it's
>>> always best to set link speed and duplex manually at both ends to remove
>>> any possible issues with link negotiation.
>>
>> That hasn't been the right thing to do for at least 8 years or so,
>> probably 10 or more.
>>
>> Yes, back in the 90's when all of this stuff was still new it was not
>> uncommon to have autonegotiation issues, but any even sort of modern
>> hardware (on either side of the link) will do better with auto than not.
> 
> Some of us still work at places where the hardware is 10 years old, you
> know. :)

True ... hence my careful specification of "sort of modern." :)

> I do still see fixed setups in service provider handoffs - for example
> this colo, Level3 and Hurricane.  Also all our metro ethernet stuff
> specifies a fixed configuration.
> 
> From what I can gather, this seems to be the standard practice in that
> space, but then again you're supposed to be plugging into equipment that
> wouldn't have the buffer issues that a $450 Dell switch would have.

Well one could also say that this sort of thing tends to result from
the, "There is a knob, I MUST twist it!" syndrome.

> The rule I recall is never do autoneg on one side and fixed on the
> other, that more often than not will end up in a duplex mismatch.

Yes, that's definitely true, and I should have mentioned it. Whatever
you do on one side (auto/manual) you must also do on the other.


Doug

-- 

	Nothin' ever doesn't change, but nothin' changes much.
			-- OK Go

	Breadth of IT experience, and depth of knowledge in the DNS.
	Yours for the right price.  :)  http://SupersetSolutions.com/




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