broken updates

Heyas,
        I updated from the bell replica today and,
as has happened several times before, the successive
build fails with errors. Most of the time its a 
'name not declared', etc. It would be nice to have
replica branches (e.g. CVS -current -stable) so I
can still track the "bleeding edge", yet, maintain
a stable environment. Any ideas on this?
Don
p.s. I went to a lecture, recently, on the analysis
of TCP based on fractal patterns. The speaker was
from AT&T Labs. I am wondering if any of that 
research was initiated before the split with Lucent
(I havent had time to read the .ps...), and, if so,
is there any theoretical application for generating
new calculations and improvements to streamline
cross-network communications?