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RE: Source address selection insufficient?
> Correct. If the only thing you do is try the four pairs, it may happen
> that no pair works. It is somewhat unlikely in practice, since sites
> tend to have a "default" provider, and the pair default-default ends up
> working. But it is definitely a possibility, in a "shoot your-self in
> the foot" kind of way.
Does this mean that we can remove the two solutions in your draft
(solution 2 and 7) which use source address selection as the means
to avoid ingress filtering issues?
> Locator rewriting supposes that both sites (X and Y) cooperate. If that
> is the case, you can also implement an end-to-end solution, e.g. X sends
> "A:X-C:Y", Y replies A:X-D:Y, and both decide to agree on the result.
Not only that - it also assumes that the peer host has been modified
to be able to handle locators that are rewritten.
Thus it would take longer to deploy etc. etc.
> Relaxed filtering and source-based routing are "local" solutions: they
> make no hypothesis on the behavior of the remote site.
> Source based routing is trivial to implement in single-subnet sites.
Yep. But it becomes a lot more complex as the site grows.
If we decide that source-based routing only applies to a subset of the sites,
e.g. due to large sites being able to use relaxed filtering, then the incentive
for wide-spread implementation of these more complex techniques might be a