Ooops, I meant 5.12 microseconds for 100-Mbps. I was rushing off to go
skiing! This has been a good discursion. Thanks to everyone who
participated. I don't think Cisco spends enough time teaching people the
basics of Ethernet. I'm glad to see people are still interested (well, sort
of interested, anyway.)
Priscilla
At 10:55 AM 12/26/00, Priscilla Oppenheimer wrote:
>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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> > >
> > >
> > > ________________________
> > >
> > > 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
>
>_________________________________
>FAQ, list archives, and subscription info:
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>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
________________________
Priscilla Oppenheimer
http://www.priscilla.com
_________________________________
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