[Bioclusters] Xserve going full duplex

andy law (RI) bioclusters@bioinformatics.org
Tue, 12 Aug 2003 11:40:04 +0100

Donald Becker wrote:

> That is a very bad solution.  If you must must disable autonegotiation
> because of flawed hardware, disable the broken end and allow 
> the link to
> use half duplex.
> Auto-negotiation is reliable, and failure is always because of flawed
> hardware.  In the past there were several switch vendors that didn't
> want to acknowledge problems with what they were shipping, 
> and therefore
> implied that auto-negotiation was flawed as a concept.  
> Modern products
> almost universally implement it correctly, and there is now a quiet
> restatement of recommended practices.
>   http://www.cisco.com/warp/public/473/46.html
> A quick background on autonegotiation is available at
>   http://scyld.com/expert/NWay.html
> Bottom line: Auto-negotiation works.  If you turn it off because of
> broken switches, never set the port forced-full-duplex mode.

But from reading Table 1 in the article on the cisco site, if the problem is at the switch end, the *ONLY* way to get a 100MB connection is to manually configure both ends. Now I'm not au-fait with the reasons to choose half-duplex or full-duplex so I could be missing the point, but I do know that if it comes to a choice between a 10MB link, a 100MB link with a mismatched duplex or a working 100MB link then I'll choose the 'bad solution' of manual configuration.



Dr. Andy Law
Head of Bioinformatics - Roslin Institute

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