On Jul 15, 2009, at 5:41 PM, Michael Powell wrote:
David Kelly wrote:
Not directly FreeBSD related, but how much of a chance is there
that two
machines could communicate directly over 5,000 feet of cat5 with no
special hardware?
IIRC the classic ethernet problem limiting the distance between the
farthest points on a network had to do with timing and collisions. If
these two NICs are configured full duplex then it seems one would
have
no idea how far away the other was due to timing issues.
No. Ethernet uses a protocol design called Carrier Sense Multiple
Access
with Collision Detect, or CSMA/CD. The maximum lengths are indeed
related to
timing and the timing is a direct result of the propagation delay
in the
medium. The velocity factor will be some percentage of the speed of
light.
Since when does one have CSMA/CD when configured as full duplex? All
full duplex ethernet connections are point to point, machine to
machine, or machine to switch. There is no multiple access on full
duplex. No chance of collision.
So I'm thinking at 5,000' the problem is one of echo cancelation and
signal loss, not one of ethernet protocol.
--
David Kelly N4HHE, dke...@hiwaay.net
========================================================================
Whom computers would destroy, they must first drive mad.
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