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Re: Turning off CRC check in NIC

To: chuckw@xxxxxxxx
Subject: Re: Turning off CRC check in NIC
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Tue, 13 Nov 2001 20:17:01 -0700
Cc: netdev@xxxxxxxxxxx
Organization: Candela Technologies
References: <20011110134559.A19083@ratula.moonlight.se> <20011113212805.C2841@ieee.org>
Sender: owner-netdev@xxxxxxxxxxx
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chuckw@xxxxxxxx wrote:

On Sat, Nov 10, 2001 at 01:45:59PM +0100, Carl-Johan Bostorp wrote:

Hello,

I want to turn off the CRC check on ethernet frames and pass every packet up to 
the kernel. I have an eepro100, so I mailed Intel about it and asked for specs. 
The reply I got was that the kernel may actually rely on the NIC doing this 
check.

So, what's the deal? What effects will there be if the NIC starts passing 
everything up to the kernel?


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I would think there would be many problems with this. One being
that the protocol field may be mangled, then the kernel wouldn't know what to do with the packet.


So the kernel drops it if that is the case, and you are no worse off
than before (not counting processing time).  No protocol should ever
assume it will not be sent shitty packets of every imaginable type:
the protocols must be able to handle such things gracefully, though
they can surely toss the packet away or otherwise ignore it...

Enjoy,
Ben



Chuck




--
Ben Greear <greearb@xxxxxxxxxxxxxxx>       <Ben_Greear AT excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear



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