Focussing:
> In particular, the benefits would be the capability of establishing > new communications through the alternative paths.
Well, that is an intrinsic property of IPv6 surely - if a host has two addresses, and one fails, you can try the other. But since we can only get ULID to locator translation with a shim at both ends, I just don't see what is brought to this property by the shim; both ends will have to use the new locators at the ULP interface, so the shim has no work to do.
I guess Marcelo is talking about the logic to try another source address. The actual shim6 protocol would not be of use here.
So, the question we have now is whether the SHIM6 WG's RFCs should specifically deal with the source address selection problem when the other end is plain old IPv6 node. Or not.
--Jari