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Posted by glen herrmannsfeldt on September 12, 2007, 9:53 pm
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vlsidesign wrote:
> I've heard that repeaters don't amplify a signal, but that they
> recreate it.
More or less, the bits are decoded, including reclocking, and then
recreated on the other side.
> Are they only used on Ethernet networks and deal only with Ethernet
> frames? Does recreate the signal mean they repeat the 0's and 1's and
> have no idea about actual frames?
There might be some that don't know about frames, but none that
are part of the standard (that I know of).
> I've also read that you can connect two Ethernet network segments to
> repeaters, especially in the older technologies (10base2, 10base5?).
> And that when one segment has a break and gets reflection and brings
> down this segment that it doesn't affect the other segment. How does
> this happen?
In many cases, such as a break in the cable, a large number of
collisions will be generated. Repeaters detect this and stop repeating
the data until the problem is fixed. A short in the cable (shield to
center conductor) will result in no data and no collisions. In that
case, there is nothing to repeat.
> It would seem like it would simply repeat the reflections/
> collisions to the other segment and bring down the other segment, it
> would seem to have some sort of intelligence, even though it is
> sometimes referred as a dumb device.
It doesn't take much to realize that the collision rate is high.
There is also jabber detection, when a sender sends much more than
one packet without stopping.
-- glen
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