At 07:41 AM 2/28/01, anthony kim wrote:
>Neil is correct. Fast ethernet can be used in a shared medium environment
>(repeaters, fast hubs) that don't support full-duplex.
>
>http://www.cisco.com/warp/public/cc/so/neso/lnso/lnmnso/feth_tc.htm
Nice paper. I just wanted to add my $.02 after seeing some of the other
messages that garbled the issue. The speed of the connection (10Mbps,
100Mbps, 1000Mbps) is not relevant to the question of whether one can use
half or full duplex. IEEE standardized full duplex in 1997 for a variety of
speeds and media.
If there are multiple stations sharing a medium (cable or hub), then you
can't use full duplex. You must use CSMA/CD, which is also called
half-duplex to distinguish it from the newer full duplex method. In a
shared network, receiving while you're sending is normal, but it is also
considered a collision. All stations must recognize the collision and the
senders must back off, wait a random amount of time and resend.
If there are just two stations sharing the medium, you can usually use full
duplex. For full duplex to work, each station must have a distinct transmit
and receive path. (It wouldn't work on coax cable, for example, but it can
work on UTP). In this case, receiving while you're sending is normal and is
not a collision. The stations are connected back-to-back. The medium is not
really shared, so collisions are not an issue. Examples include two
switches connected together and a single end-station connected to a single
port on a switch.
Regarding the original question, though I couldn't find a URL to confirm
this, I don't think the Ethernet AUI port on the 2500 series Cisco router
supports full duplex. I think the 2500 routers came out before full duplex
Ethernet existed for one thing. Also, I doubt that it is possible to
support full duplex with an AUI attachment. You would need a way to tell
the transceiver to ignore collision detection, and that's probably not
supported.
Hope that clear things up a bit.
Priscilla
>--- SAIF <[EMAIL PROTECTED]> wrote:
> > 100mbps is not ethernet be sure its fast ethernet ,also their is no
> > collisions in fast
> > ethernet ,its colliision free and this is only possible if u have one
> > way to send and
> > one way to recieve data simultaneously :) i am sure u got the idea
> > secondly in ethernet there are collisions and if there are colliisions
> > Can u use one to
> > send and one way to recieve simultaneously with collisions so if u cant
> > the result is
> > ethernet works in half duplex mode and fast ethernnet works in full
> > duplex
> > if u have any thing different than me plz share with us
> > waiting ur reply
> > Saif
> >
> > Neil Schneider wrote:
> >
> > > It is NOT true that ethernet is half and fastethernet is full duplex.
> > > Either 10Mbps or 100Mbps ehternet can be run in half or full duplex
> > mode.
> > > And offhand I don't know if the 2500 AUI port will do full ethernet.
> > >
> > > --
> > > Neil Schneider
> > > MCT MCSE CCSI CCNP
> > >
> > > "SAIF" <[EMAIL PROTECTED]> wrote in message
> > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > > NO ITS ETHERNET PORT AND WORKING HALF DUPLEX ONLY ,U SEE CISCO GIVES
> > > FASTETHERNET PORTS
> > > > SPECIALLY IN THEIR ROUTERS SPECIALLY IN 4XXX SERIES AND U KNOW
> > ETHERNET
> > > WORKS IN HALF
> > > > DUPLEX AND FASTETHERNET WORKS IN FULL DUPLEX SO THE RESULT IS AUI
> > PORT IS
> > > HALF DUPLEX
> > > > ETHERNET NOT AUTO SENSE AND IF U WANT AUTOSENSE 10/100 BASE T GO TO
> > ANY
> > > OTHER ROUTER
> > > > ,CHECK THE ROUTER;S MANUAL :)
> > > > HOPT IT WILL HELP
> > > > IS IT ?
> > > >
> > > > Turfis wrote:
> > > >
> > > > > Is the Ethernet AUI port on the 2500 series Cisco routers Full
> > Duplex
> > > > > compatible? Does it autonegoiate? Can you hard code the
> > interface for
> > > > > half/full/auto? Thanks!
________________________
Priscilla Oppenheimer
http://www.priscilla.com
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