27 Jun
2018
27 Jun
'18
10:45 a.m.
On Wed, Jun 27, 2018 at 10:59 AM, Paul Koning <paulkoning at comcast.net>
wrote:
Interesting! I won't disagree with what you're saying, since I'm ignorant
of these details, but in my experience 10BASE-2 networks usually had far
_more_ nodes on a network than any 10BASE-5 network I saw. I routinely saw
over 100 nodes on a 10BASE-2, but I never saw more than 20 or so on a
10BASE-5. (There certainly may have been larger 10BASE-5 networks; I only
ever saw about a dozen 10BASE-5 networks.)
On Jun 27,
2018, at 12:36 PM, Eric Smith via cctalk <
cctalk at classiccmp.org> wrote:
Collision detection was the reason (or at least
_a_ reason) why the
spacing
of taps on the 10BASE-5 "thick"
Ethernet cable was required to be an
exact
multiple of 2.5m. It was never clear to me why
this was not also a
requirement for 10BASE-2 "thin" Ethernet.
Yes, to avoid false alarms. The purpose of the spacing rule is to ensure
that there is enough signal integrity that you do not get spurious
collision indications due to reflections off the impedance variations along
the cable. On a segment with few transceivers, there is enough margin that
the rule doesn't matter. This is why 10Base-2 doesn't have that rule: the
station count limit is low enough that it isn't needed.