[OT] Ethernet Auto Protocol Negotiation ?

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I am asking in this group, since it is a group I read most often, and
I expect that people that contribute to this group might actually know
the answer.

I have a small home PC network with 2x Win2K machines and one Linux
(RH 9) machine. I have 10/100 el-cheapo Accton Ethernet cards in one
W2K machine and in the Linux machine connected via a 8 port 10/100
switch. The third machine uses the nVidia nForce2 onboard ethernet.
On both w2k machines the protcol is set to auto. I presume it would be
the same on the RH9 machine, but at the moment I am not sure where to
verify this.

I am experiencing that sometimes the comms between the machine with
the nVidia machine and the others is extremely slow. I have to
poweroff the machine, and restart (Sometimes a number of times) before
the speed is back to what it should be.

I expect somthing is probably going wrong during the protocol
negotiation phase.
Is there some way to check what protocol has been negotiated by the
different machines ?
Is there some way to force all the machines to use a specific
protocol. ?

   Anton Erasmus

Re: [OT] Ethernet Auto Protocol Negotiation ?
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Mis-matched duplex can be a source of performance problems, particularly
when the traffic volume is high on the link.  One end is observing
CSMA/CD (half duplex mode) and the other is ignoring it (full duplex
mode).  This causes the half duplex device to incur a high volume of
collisions, which could be noticable under heavy volume.

When using a 10/100 switch, there's rarely a reason not to use full
duplex for best performance.  The exception is when the connected device
is a shared (half duplex) hub.  All this is normally negotiated
automatically; it *usually* works fine in 100Mb (and 10/100 auto) mode;
it's not reliable in 10Mb mode.

Suggested NIC driver settings, in order of preference:
10/100 auto w/ auto duplex
10/100 auto w/ full duplex
100 w/ full
10 w/ half

Re: [OT] Ethernet Auto Protocol Negotiation ?

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Check for a duplex mismatch (mii-tool is the tool in Linux). If a controller
is set to full duplex, it's no more listening to the other traffic before
sending, so in a half duplex network leg it will cause plenty of collisions
(check with ifconfig).


Tauno Voipio
tauno voipio @ iki fi

Re: [OT] Ethernet Auto Protocol Negotiation ?
On Wed, 17 Dec 2003 17:12:33 GMT, "Tauno Voipio"

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Thanks for the replies. I have googled for mii-tool, which seems to be
part of a "net tools" package. I have however been unable to find the
home page for this particular project. Do you maybe have an URL where
I can get the source for this tool.

   Anton Erasmus

Re: [OT] Ethernet Auto Protocol Negotiation ?

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A quick google-search gave this link ;-)

http://freshmeat.net/projects/net-tools /


Re: [OT] Ethernet Auto Protocol Negotiation ?
On Thu, 18 Dec 2003 21:16:12 +0100, Jan-Hinnerk Reichert

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I also eventually found the URL:
http://www.tazenda.demon.co.uk/phil/net-tools /

I also found a RH9 rpm version, but when I tried to install,
I was informed that net-tools are already installed.
It seems I have version 1.55 of net-tools on RH9, but
mii-tool seems to be missing.


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