rc(8) script -- waiting for the network to become usable

[Phil]

Jeremy, 
A good proposal to improve start-up robustness. If I may suggest, 
waitnetwork_ip should include a short list of alternate IP's in 
the event of a local network outage, or DOS, etc.  Something like:
waitnetwork_ip="IP1 IP2 IP3"

Having multiple target IP's will improve the likelihood of timely 
booting when silly/nasty things happen on the wider network.

Good idea to have incorporated into the base system.

Andrew, 
I agree that the problems should be corrected at the source;
and my preference is to fail properly (b) so that other mitigation
may occur.  Done in parallel, would eventually provide a belts 
and braces start-up: wait for the network, and fail properly for 
network dependent processes.  
(I can't speak to desktops that resume from a suspend when the 
network has changed state.)
Regards, Phil