eepro100 confusion

Florian Gabriel fgp at pcnet.ro
Mon Nov 11 12:36:39 EST 2002


Donald Becker wrote:

>On Thu, 24 Oct 2002, Michael Stein wrote:
>
>  
>
>>>I recently had two IBM Linux clusters installed at my work site. Due to
>>>certain customer issues, our cisco switches have all ports set to 100Mbits
>>>Full Duplex for all server connections.
>>>      
>>>
>>My understanding is that setting ports to 100 Mbits/full duplex will
>>PREVENT the NICs from negotiating thus requiring specifying the matching
>>values on every server NIC.
>>    
>>
>
>Correct.  To repeat the point: forcing full duplex will turn off
>autonegotiation, and often link speed sensing.
>
>  
>
>>If not specified on the server the server should, without negotiating,
>>default to half-duplex, thus resulting in a duplex mismatch.
>>    
>>
>
>Correct.
>
>  
>
>>There might have been a time years ago when FE negotiating was a problem,
>>but shouldn't we be way past that by now?
>>    
>>
>
>I answer questions relating to this issue every day.
>The problem sites are those with Cisco switches and administrators with
>Cisco training.
>
>Cisco switches had a broken autonegotiation implementation.  Rather than
>fix the deployed hardware, Cisco taught that autonegotiation was
>unreliable and should be turned off.  OK.  But they went further and
>recommended forcing full duplex.
>  
>
A new document ( http://www.cisco.com/warp/public/473/46.html ) can make
some light here.

>>This maximizes the effort/support needed on each and every server.
>>    
>>
>
>That's the big problem.  The result is that every connected machine must
>now be specifically configured.  Rather than having plug-and-play
>computing resources that work out of the box, you need installation
>people that understand the configuration specifics of each device.
>
>  
>

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