Using diffserv for signalling whether rewriting is allowed doesn't get too much in the way of regular diffserv use.
I think it does. There are moves afoot to define recommended service classes and recommended DSCP mappings (for example draft-baker-diffserv-basic-classes-**.txt)
and overloading these bits within a mere 6 bit code space seems to me to be one bridge too far.
I'd much rather
look at using two different flow labels, where we have a much larger code
space and no suggestion of pre-existing semantics.
And I wish people would think about routers that will be shipped ten
or fifty years from now. If the solution is sub-optimal for today's hardware, that should not in itself be a show-stopper.
Interesting point. I sort of agree. I don't think it applies here,
though. Using the diffserv bits is the most logical and cleanest choice
if we can make it work, and I believe we can.
My point is that even if people think it is slow to look at an extra header
today, this is probably irrelevant in the long term.