Re: Auto-sensing for IPS devices

[Joel M Snyder <Joel.Snyder () Opus1 COM>]

> Setting a switch port to 100-TX will force any decent NIC on a
> host to link up at that setting.  I would trash any NIC that
> doesn't.  It's not necessary to force the link mode of the NIC
> if the switch doesn't auto-negotiate - the host NIC will find
> the desired link setting.

No, that's not the way it works.  What you're doing is forcing the NIC 
to go into fallback mode, and what you're hoping is that it will be 
100Mbit/Full Duplex.  It happens that most NICs do that, and this is why 
the results you're seeing are as favorable as they are.  If you picked a 
different speed or duplex, you'd have a bunch of NICs that would 
suddenly stop working.

However, with the world of 1000Mbit pushing 10/100 out of the way, your 
technique is going to result in much lower success rate and much higher 
customer support calls and problems.

If you want reliable operation, you must set speed and duplex settings 
on both ends.  There is no concept of a NIC "figuring it out" or being 
able to be "forced." If you turn off autonegotiate, there is no way in 
the standard for the NIC to sense what the speed & duplex settings are.

jms

--
Joel M Snyder, 1404 East Lind Road, Tucson, AZ, 85719
Phone: +1 520 324 0494 (voice)  +1 520 324 0495 (FAX)
jms () Opus1 COM    http://www.opus1.com/jms    Opus One

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