Date: Fri, 28 Feb 2003 23:38:42 +0100 From: Cliff Sarginson <cls@raggedclown.net> To: questions@freebsd.org Subject: Re: full/half duplex Message-ID: <20030228223842.GA81663@raggedclown.net> In-Reply-To: <20030228212700.GA83015@constans.gldis.ca> References: <1046381078.2126.19.camel@ka0ttic> <001201c2deb9$2b29a220$1508060a@furrie.net> <20030228192335.GA10452@raggedclown.net> <20030228212700.GA83015@constans.gldis.ca>
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On Fri, Feb 28, 2003 at 04:27:00PM -0500, Jeremy Faulkner wrote: > On Fri, Feb 28, 2003 at 08:23:35PM +0100, Cliff Sarginson wrote: > > On Thu, Feb 27, 2003 at 11:37:19PM -0000, Chris Phillips wrote: > > > Aaron wrote: - > > > I have a 3Com 3c900-Combo and ifconfig is reporting that it was in > > > half-duplex mode, so I booted up my 3com dos utility book disk and > > > checked and it was at half-duplex so I changed it to full. ifconfig is > > > still reporting it being half-duplex. Do I need to reinstall the driver > > > or something? How would I go about it? > > > > > > Chris Phillips wrote: > > > > Is it plugged into a hub or a switch? > > > > A hub will only do half duplex. > > > > A switch will do full duplex. > > > > Worth mentioning... > > > > > I don't know what the problem is but I do not think what you say is > > correct. A hub can do full duplex, at least in my previous experience. > > A hub most certainly can not run full duplex. In order to run at full duplex > the tx and rx lines have to be separate. > > A hub is simply connecting all of the tx and rx lines in the ethernet cable > together w/ some amplification. Since all of the tx and rx lines are connected > a packet transmitted from one machine will be received by all machines on > the network. > > A switch can do full duplex because each port is essentially its own nic > card. The switch segments the network and only traffic that needs to go > through a specific segment will go to that segment. This division of > traffic is decided based on the mac address of the destination. Well, that is true as far as it goes, but there are a few other considerations being skated over here with regard to switches. > Well, before I started using switches my eyes must have been deceiving me, because I built a small hub-based network, which was most definitely running full duplex. So it either must have been some kind of super-hub ..:) or my eyes deceived me, or one of us is wrong. Or perhaps it was a switch in a box marked hub. Or maybe the O/S was lying. Well I don't have the device anymore, so I can't try it out. This argument has been on this list once before btw, a long time ago, I don't think I participated in it, but I do recall dissent on this very topic...even among experts. Still I am not an electrical engineer, I only believe what I see with my own eyes :). -- Regards Cliff [ This mail has been checked as virus-free ] To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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