So collisons are head on wrecks and if  serial could have  a wreck it would
be just a rear end deal .. LOL I bit at one time

Re the cable stuff
The Media Access Control mechanism is normally implemented in hardware or in
a combination of hardware and software. The primary purpose of the MAC is to
share the media in a reasonable way. Both the CMTS and the Cable Modem
implements protocols to do

Ranging to compensate for different cable losses. It is essential that the
upstream bursts from all Cable Modems are received in the Head-End at the
same level. If two Cable Modems transmit at the same time, but one is much
weaker than the other one, the CMTS will only hear the strong signal and
assume everything is okay. If the two signals are same strength, the signal
will garble and the CMTS will know a collision occurred.

Ranging to compensate for the different cable delays. The size of a CATV
network calls for fairly large delays in the millisecond range.

Assigns frequencies etc. to the Cable Modems. The Cable Modem first listens
to the downstream to collect information about where and how to answer. The
it signs on to the system using the assigned upstream frequency etc.

Allocate the time-slots for the upstream.

It is impossible to give more detailed information about the MAC, without
going into the specific standards. This is one of the areas that are most
closely tied to the specific standard.

Stolen from here
http://www.cable-modems.org/

Oz


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