Yes guys, okay it makes sense.
But this means if you have a half duplex connection between the host and the
switch , the contention will be between the host from one side and on the
other side is what ever data goining to the direction of the switch.
sense ?
On Tue, 26 Dec 2000 19:26:56 -0500, Bowen, Shawn wrote:
> Yup, makes sense. I can only speak for 3Com on this one, but I believe
> Cisco implements similar features. On a 3Com Corebuilder (as well as
their
> Workgroup Switches) they use fake collisions as a flow control mechanism.
> In other words if there was contention at the server or switch and they
> couldn't handle the load then a collision (a JAM) will be sent. Now,
that
> said after we all just agreed that collisions can not happen on a full
> duplex Ethernet segment:) If you notice in Cisco texts that Collision
> Detection is disabled on full duplex links, this is not true. Collision
> detection is still there, at least on a 5000 and can be simulated by
loading
> up a server at 10MB FD with a few 100MB FD clients on the other end of
the
> Cat, you will see this in action. 3Com does the same thing, I thought
this
> was kinda interesting.
>
> Shawn
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> Priscilla Oppenheimer
> Sent: Tuesday, December 26, 2000 2:06 PM
> To: Andy Walden; John lay
> Cc: [EMAIL PROTECTED]
> Subject: Re: Confused (was Re: is this statement true ??)
>
> I think what John is getting at is that there is still contention. In his
> example with two clients trying to reach one server, there's contention
at
> the switch, and at the server possibly. There's no contention on the
medium
> itself. There's only one device trying to send at any one time. The
switch
> has its transmit pair and the server has its own transmit pair. If the
> switch has two frames to send to the server, the backup happens at the
> switch. Does that make sense?
>
> Priscilla
>
> At 08:33 AM 12/26/00, Andy Walden wrote:
>
> >This is correct. You don't use full duplex if you are competing for
> >bandwidth, ie, plugged into a hub. But if you are plugged into a switch,
> >there is only one bandwidth domain between the device and switch and
> >with nothing competing for the bandwidth on that link so you can go full
> >duplex.
> >
> >andy
> >
> >On Tue, 26 Dec 2000, John lay wrote:
> >
> > > Priscilla, everybody,
> > >
> > > I am confused. Ethernet and FastEthernet uses the CSMA/CD as a
channel
> > > allocation techinque in a shared media access envoiroment.
> > > Here it comes the confusion, when you are saying that the Full-duplex
> does
> > > not support CSMA/CD because the transmit and receive are on different
> > wires.
> > > This implies that in this case there is no shared media, how come if
> you
> > > have two clients competing to talk to the same server
> simultaneously....!!
> > >
> > > Thanx
> > >
> > >
> > > On Mon, 25 Dec 2000 16:36:11 -0800, Priscilla Oppenheimer wrote:
> > >
> > > > It's true for Ethernet because Ethernet's CSMA/CD media access
> control
> > > > method has strict timing requirements, which result in strict
length
> > > > restrictions. Half-duplex uses CSMA/CD. Full-duplex does not.
> > > >
> > > > I wouldn't say it's true in general, however.
> > > >
> > > > Priscilla
> > > >
> > > > At 05:32 PM 12/25/00, Li Song wrote:
> > > > >"full-duplex can be used over longer distance than
> > > > >half-duplex" ??
> > > > >what 's your opinion ??
> > > > >
> > > > >
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> ________________________
>
> Priscilla Oppenheimer
> http://www.priscilla.com
>
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