Network problem

[bscott at ntisys.com]

On Thu, 28 Aug 2003, at 8:56pm, cbrenton at chrisbrenton.org wrote:
> Since a hub is little more than a line amplifier, it does not "transmit"
> per CSMA/CD, and thus has no way of detecting collisions. If a hub had
> this type capability, we really would not need switching as it would be
> trivial to retime the circuit as well.

  I'm pretty sure that's wrong.  Repeaters are more then just simple
amplifiers.  They also retime the signal and do some other magic that I
don't understand.  I also believe they are required to detect collisions and
generate a jam signal if one occurs.  I'm not an EE, so I don't really
understand the whys and hows, but that's my understanding of the concepts.  
I've actually gone so far as to look it up in IEEE 802.3-2002, and the parts
that I understand seem to corroborate this.

  I'm interested in improving my understanding of this stuff, so if you (or
anyone else) would like to discuss this further, please contact me off-list.  
In particular, your description of collision detection does not seem to
match what's described in 802.3-2002.  On the other hand, I can't seem to
find any explicit mention of collision detection for the transmitter at all.

-- 
Ben Scott <bscott at ntisys.com>
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