HP3000-L Archives

May 2007, Week 3

HP3000-L@RAVEN.UTC.EDU

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Subject:
From:
Jeff Kell <[log in to unmask]>
Reply To:
Jeff Kell <[log in to unmask]>
Date:
Mon, 21 May 2007 09:52:17 -0400
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Tom Hula wrote:
> The switch still thinks the
> connection is Half, even with recycling the power and changing
> ports on the switch. I'm not sure what the problem is...or if there
> is a problem, but again, thank you all. 
Short answer...

* turn off negotiation at the switch and hard code it at 100/full, *or*
* turn ON negotiation at the 3000

Longer answer...

Older hardware and negotiation schemes were somewhat optimistic.  
Autonegotiation is supposed to work according to a standard (eventually 
802.3u clause 28, later extended in 802.3ab) where there is an actual 
exchange of data between both ends of the connection.  If both ends 
don't fully support autonegotiation, some implementations would be 
"optimistic" and try to detect the link characteristics on their own to 
try to provide full-duplex if it appears to be allowed. 

Most current schemes are instead pessimistic and will "fall back" to 
half-duplex when in doubt (which is according to standard).  So a 
"standard" device set for autonegotiation will only speak full-duplex if 
both ends establish mutually agreeable autonegotiation.

Jeff

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