Re: Signatures and Authentication information must go at end of meesage.

Phil, this statement is incorrect.

Even a VERY heavily loaded ethernet if properly configured sees low
collision rates.

Ethernet does carrier sense; i.e. you don't start to send anything unless
you detect the cable is idle, so the only time collisions occur
is when two stations attempt to transmit at almost the same instant
(determined by the propogation time of the transmission line).

Note that some people's ethernet segments are improperly configured,
losing carrier sense (by chaining too many levels of repeaters).  Such a
network may have a non-trivial collision rate.  This is a 
violation of the ethernet spec, and you deserve what you get.  If you
see a significant collision rate on an ethernet, it is a VERY strong
indication that your network is actually broken.
				- Jim