You mean 512 bits or 64 bytes. A single collision domain must be limited in
size to make sure that a station sending a minimum-sized frame (512 bits)
can detect a collision reflecting back from the opposite side of the
network while the station is still sending a frame. The time is 51.2
microseconds for 10-Mbps Ethernet and .512 microseconds for 100-Mbps Ethernet.
Priscilla
At 04:11 PM 12/26/00, leonz wrote:
>or more precisely, it's the 52 bit-time rule. Where the maximum round-trip
>time
>in a segment can not exceed the time needed to transmit 52 bits. Ie, if it's
>a 10M
>network, it has to take less than 5.2 us, if it's 100Mb network, then it'll
>be 0.52 us
>
>Leon Chang
>CCNP, CCDA
>
>
>----- Original Message -----
>From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]>
>To: "Bowen, Shawn" <[EMAIL PROTECTED]>; "Li Song" <[EMAIL PROTECTED]>;
><[EMAIL PROTECTED]>
>Sent: Tuesday, December 26, 2000 1:47 PM
>Subject: RE: is this statement true ??
>
>
> > 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 ??
> > >
> > >
> > >_________________________________
> > >FAQ, list archives, and subscription info:
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> > >
> > >_________________________________
> > >FAQ, list archives, and subscription info:
> > >http://www.groupstudy.com/list/cisco.html
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> >
> >
> > ________________________
> >
> > Priscilla Oppenheimer
> > http://www.priscilla.com
> >
> > _________________________________
> > FAQ, list archives, and subscription info:
>http://www.groupstudy.com/list/cisco.html
> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
> >
> >
>
>_________________________________
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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