The question was whether full-duplex can be longer than half-duplex. This
is only an issue for Ethernet CSMA/CD and it has nothing to do with
attenuation.
Priscilla
At 01:31 PM 12/26/00, Tony van Ree wrote:
>Hi,
>
>Be aware that the are two points here one is the collision type argument
>that is we need to be sure all have seen the pulses on the line prior to
>themselves transmitting. The other is pure attenuation that is the
>weakening of the signal as it attempts to change the state of the
>line. (Assuming electricity does not really travel along the wire but
>does indeed change its state the same could be said for fibre.)
>
>So there are a number of factors that come into it.
>
>Teunis
>Hobart, Tasmania
>Australia
>
>
>On Monday, December 25, 2000 at 04:47:24 PM, Priscilla Oppenheimer wrote:
>
> > At 01:07 PM 12/25/00, Bowen, Shawn wrote:
> > >According to IEEE NO, 100 Meters is the max cable distance for Half or
> Full
> > >100MB Ethernet over TP. In reality, Yes it will extend the range, The
> > >reason why is that at full duplex you can not have collisions, and
> > >collisions are the main reason for the distance limitation (Cross Talk
> comes
> > >into play as well). The reason behind this is that in the original IEEE
> > >spec the distance limitation was set so that a single 64Byte packet (the
> > >smallest) could be transmitted down the line and would collide with
> another
> > >packet before the 64Byte packet header had been completely
> transmitted, when
> >
> > Minor correction: The distance limitation is defined so that if a station
> > is transmitting a minimum-size frame (64 bytes) and a collision occurs at
> > the other end of the network, the collision will reflect back to the
> sender
> > while the sender is still sending. If this didn't happen, the sender would
> > have stopped monitoring for a collision with its transmission, and would
> > not automatically retry. An upper layer would have to retransmit, which
> > takes a lot longer.
> >
> > >this does not happen properly you see late collisions, these indicate a
> > >collision past the preamble header of the packet and indicate a cable
> length
> > >that is to long.
> >
> > A late collision is one that happens past the preamble and past the first
> > 64 bytes of the frame. A collision within the first 64 bytes is legal,
> > normal, and not late.
> >
> > Priscilla
> >
> > >If you need to even go close to the 100 Meter mark you
> > >should consider 100BaseFX or similar.
> > >
> > >Shawn
> > >
> > >-----Original Message-----
> > >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Li
> > >Song
> > >Sent: Monday, December 25, 2000 4:33 AM
> > >To: [EMAIL PROTECTED]
> > >Subject: is this statement true ??
> > >
> > >"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
> >
> > _________________________________
> > FAQ, list archives, and subscription info:
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> >
>
>
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Priscilla Oppenheimer
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