10Base5/Thicknet (was Re: SUN networking problems)

From: Dwight Elvey <elvey_at_hal.com>
Date: Sat Mar 24 17:07:13 2001

On Sat, 24 Mar 2001, Tony Duell wrote:

> >
> > On Mar 23, 17:42, Bill Gunshannon wrote:
> > >
> > > Two points.
> > >
> > > First, "a piece" of yellow cable won't work. The lengths were part of
> > the
> > > spec and very important. Having to do with reflections and such (anybody
> > > here still have a TDR??)
> >
> > I've not seen anything about lengths, except of course for the maximum
> > length and multiple-of-2.5m tap separation. I'm told the standard
> > specifically allows for lengths to be joined at intervals which are *not*
> > multiples of 2.5m, and the overall length does not have to be an exact
> > multiple either.
>
> Correct (I've read the standard). And the terminators don't have to be a
> multiple of 2.5m from the tranceiver postiion either.
>

Hi
 I haven't been following this thread as close as I should.
I was working at Intel during the period when ether net was just
being defined. The reason for the 2.5m spacing was to insure that
any collision was detected by all of the unit on the wire.
The idea was that the pulses would be exactly overlapped. This was
also the reason for the maximum length without repeaters. The
packet size was such that any collision was sure to be detected,
regardless of where one was along the cable.
 It doesn't make any difference where the end terminations are
placed but both ends need to be terminated.
Dwight
Received on Sat Mar 24 2001 - 17:07:13 GMT