Skip site navigation (1)Skip section navigation (2)
Date:      Fri, 28 Feb 2003 16:27:00 -0500
From:      Jeremy Faulkner <gldisater@gldis.ca>
To:        Cliff Sarginson <cls@raggedclown.net>
Cc:        questions@freebsd.org
Subject:   Re: full/half duplex
Message-ID:  <20030228212700.GA83015@constans.gldis.ca>
In-Reply-To: <20030228192335.GA10452@raggedclown.net>
References:  <1046381078.2126.19.camel@ka0ttic> <001201c2deb9$2b29a220$1508060a@furrie.net> <20030228192335.GA10452@raggedclown.net>

next in thread | previous in thread | raw e-mail | index | archive | help
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.

-- 
Jeremy Faulkner			http://www.gldis.ca

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030228212700.GA83015>