At 03:37 PM 1/22/01, Jack Williams wrote:
>The propagation delay for Ethernet must not be greater than 512 bit times or
>you'll get late collisions (as Tim said). Since the speed of light is
>constant and 10-baseT bits last 10 times longer than 100-baseT bits, that
>directly influences how long of a cable you can run!
>
>That sounded like Nonsense, didn't it?
It doesn't sound too much like nonsense. :-) I think the part that people
miss when they read the jargon in some books is the relationship between
512 bit times and 64 bytes. 64 x 8 = 512. The minimum size frame is 64
bytes. It takes 512 "bit times" to send it. Sounds obvious, but I think we
miss the obvious sometimes....
The physical size of the network is limited so that a station is still
sending the minimum size frame (64 bytes) if a collision occurs and
reflects back to the sender. If the sender were not still sending, the
frame would have to be retransmitted by a higher layer. For an upper layer
to notice that the frame needs retransmitting takes much more time.
Ethernet retransmissions occur within nanoseconds usually.
Priscilla
>------Original Message------
>From: [EMAIL PROTECTED] (Timothy Metz)
>To: Alvarado Jesus <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
>Sent: January 22, 2001 7:43:48 PM GMT
>Subject: RE: EASY ?? FOR MOST OF YOU
>
>
>It's B.
>
>I think we just had this discussion not too long ago, it was quite a long
>thread with a lot of discussion on slot time (or the Cisco equiv term).
>
>Tim
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> > Alvarado Jesus
> > Sent: Monday, January 22, 2001 8:11 PM
> > To: '[EMAIL PROTECTED]'
> > Subject: EASY ?? FOR MOST OF YOU
> >
> >
> > The network span of a 100Base-T Network (205) meters is approx. 10 times
> > smaller than the network span of a 10Base-T network (2500) meters Because
> > ....
> >
> > A) , Higher speed data signals attenuate more quickly and so cannot be
> > transmitted that far
> >
> >
> > B) . Both Networks have minimum frame sizes of 64 bytes and the network
> > spans must be tied directly to the minimum frame transmission
> > time to avoid
> > collisions.
> >
> > _________________________________
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Priscilla Oppenheimer
http://www.priscilla.com
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