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Re: Turning off CRC check in NIC

To: Donald Becker <becker@xxxxxxxxx>
Subject: Re: Turning off CRC check in NIC
From: Carl-Johan Bostorp <ctor@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Sun, 11 Nov 2001 18:56:44 +0100
Cc: netdev@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.10.10111101829280.686-100000@vaio.greennet>; from becker@scyld.com on Sat, Nov 10, 2001 at 06:31:37PM -0500
Mail-followup-to: Carl-Johan Bostorp <ctor@xxxxxxxxxxxxxxxxxxx>, Donald Becker <becker@xxxxxxxxx>, netdev@xxxxxxxxxxx
References: <20011110134559.A19083@ratula.moonlight.se> <Pine.LNX.4.10.10111101829280.686-100000@vaio.greennet>
Sender: owner-netdev@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
On Sat, Nov 10, 2001 at 06:31:37PM -0500, Donald Becker wrote:

> > I want to turn off the CRC check on ethernet frames and pass every
> > packet up to the kernel.
> 
> Why?

The network I'm on is built with 3 24-port hubs in serial, who is then 
connected to a switch. But the hubs use some kind of encryption for the 
packets. Recently I was at a friends place to check out his net (same thing 
there) and on his PPC with Linux, all frames were passed to the kernel. It was 
possible to see the source MAC on the packets. The NIC was a 3Com of some sort.

It seems some people on the net has full duplex turned on which of course ruins 
performance pretty badly (ping varying between <1ms and 1000ms with packet 
loss). The landlord who provides the connection doesn't really care, but if I 
can view the source MAC of every packet I could view the amount of traffic from 
each host and when ping suddenly starts going weird simply see who started 
sending large amounts of packets.


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