When Cisco says "Full Duplex", they typically refer
to the MAC layer function of transmitting and
receiving at the same time.
This is accomplished on ethernet by uncoupling the
Collision Detection circuit, and buffering TX and RX
in separate queues.
There is no internal 'CSMA/CD' in Cisco switches .
flem
--- woody <[EMAIL PROTECTED]> wrote:
> Further to my original post...
>
> It is possible to get collisions on a Full Duplex
> segment. Transmission
> from the switch towards the destination is a shared
> bandwidth domain (with
> other originating hosts transmitting towards the
> same destination). As such
> collisions may occur on the transmit from the switch
> towards the
> destination. CSMA/CD is used to overcome this.
> This may be done internally
> within the switch (buffering of frames etc) but it
> is still there...
>
> Keith
>
> ""Joe Martin"" <[EMAIL PROTECTED]> wrote in message
> 8fbq4s$80t$[EMAIL PROTECTED]">news:8fbq4s$80t$[EMAIL PROTECTED]...
> > Full duplex transmission requires a point to point
> connection between two
> > devices. This is achieved using a switch. Since
> the connection is
> between
> > two and only two devices at a time, this allows
> them to transmit and
> receive
> > at the same time. Thus a collision would never
> occur and CSMA/CD is
> > unnecessary.
> >
> > JOE
> > CCNP, CCDP, and a few other things...
> >
> >
> > "Dan West" <[EMAIL PROTECTED]> wrote in message
> >
>
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > Sorry to ask such a simple question--but the
> CCNA book
> > > is still unclear as to what's going on.
> > >
> > > Half-duplex ethernet uses CSMA/CD for
> arbitration on
> > > the link. Does full duplex use it as well for
> > > arbitration? The book makes it sound like if you
> are
> > > running full-duplex that the CSMA/CD is not
> necessary.
> > > It mentions half-duplex looping a duplicate
> frame onto
> > > the recieve wire from the transmit wire.
> > >
> > > Thanks.
> > >
> > >
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