On Tuesday, March 22, 2005 6:12 PM Les Mikesell wrote: >On Tue, 2005-03-22 at 16:43, Shawn Iverson wrote: >> On Tuesday, March 22, 2005 9:00 AM Les Mikesell wrote: >> > >> >Note that if you start down this route you must forever >> >manually set *every* piece of equipment plugged into your >> >network to full duplex. The problem is that setting one end >> >turns off autonegotiation so if the other end is left at auto >> >it must assume half duplex. Now that most equipment gets it >> >right I'd recommend loading the latest IOS on your cisco >> >equipment and throw away anything that still doesn't do the >> >negotiation correctly when both ends are set to auto. >> >> My experiences have shown this not to be the case. The clients are >> properly setting themselves to 100/Full, even though the >switches are >> forced to 100/full, yet the clients are left on autonegotiate. > >The negotiation process may be smarter now, but I know a few >years back setting a router/switch port to full duplex turned >off any negotiation with the connected device and any device >that did not offer to negotiate was assumed to be half duplex >by it's partner. Either that situation has changed or your >clients are doing the wrong thing even though the result is >what you want. Anyway, these days I try to leave everything >on auto unless I know that even with the latest >firmware/drivers it still won't work. > I am making a correction here for archiving purposes. I just found out that Les is correct: both sides must be auto or both sides must be forced, or else at the minimum duplex mismatches may occur. I have discovered after looking more closely in my work environment that if only one side is set to auto while the other is forced that approximately half of the ports will end up with a duplex mismatch, and the other half will end up with "late collisions" regardless of duplex (wierd...full duplex should never have collisions anyway!). Definitely leave both sides on auto unless you have a very good reason not to. I recommend these links to anyone who needs further information on this subject: http://www.cisco.com/warp/public/63/eth_collisions.html#topic4 http://www.sun.com/blueprints/0704/817-7526.pdf -- Shawn
