Alex, perhaps I was unfair about the c) option.
I understood that you'd like to replace the MF classifier on
the 5/6 tuple (adresses, DS field, protocol, ports) which I'll call
the 5F classifier by a simpler MF classifier with the flow label
in place of protocol and ports. This cancels the efficiency issue
of the extension header chain of IPv6.
My first concern is the 5F reclassification is a bad idea because
an ACL-like classifier will never give what I want as an user.
This is too rigid, not real-time, ...
The second concern is with ESP: the 5F classifier wants to look at
bits I want to hide. No conciliation is possible, IPsec people
(like Michael) will *never* accept to reveal transport layer or
payload details for a 5F classifier.
This point raises a real question about the c) option: what will
be the content of a flow label with a diffserv semantic? There are
two kinds of proposals:
- to pack some bits from protocol/ports into the flow label
(A.1 or A.2 appendix of your I-D). This will make mapping
of a 5F classifier to a flow label based one easy but
the two previous concerns apply. I vote no for this
interpretation of c).
- to use an opaque value (a PHB ID as in 7.1.1 of your I-D
is an obvious candidate) but this doesn't work if a ISP
doesn't trust you:
- there is no easy map from a 5F classifier
- or the PHB is standard and doesn't provide more information
than the DSCP, or it is not and only some ISPs can interpret it.
This kind of flow label is an extension of the DS field, it doesn't
match the requirements for the (broken) MF reclassification and
is too short for advanced features (for instance a ISP should not
rewrite it because it is hard to restore it).
I don't vote for or against the second interpretation of c) because
something is clearly broken somewhere. Tony claims that Diffserv is
broken and I believe he is right: at least the MF classifier stuff
has to be more understable... This is a ISP requirement, can ISP people
explain what they need?
Regards
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