[Babel-users] [babel] source sub-tlv

[Juliusz Chroboczek]

> Thoughts ?

I agree with all of the technical points in your mail.

Your point about combining extensions is correct, but the issue is pretty
much unavoidable now that we've committed to compositionality (the ability
to add multiple sub-TLVs to a single TLV) -- we'll unavoidably run into
the issue of what it means for an update to carry sub-TLVs from two
different extensions.  For example, we've never defined the specificity
ordering for TOS- and source-specific routes, and that's something we'll
need to do if anybody ever decides to implement doubly-specific routing.
In other words, compositionality only goes so far when total orderings and
acyclicity are involved.

From a word-smithing point of view, there are two approaches we can
consider.  Either we say nothing in the base spec, and delegate these
choices to individual extensions, or we give some guidelines for
extensions in Appendix C of the base spec.  I'll see what I can do.

-- Juliusz