> From: Harald Tveit Alvestrand <[EMAIL PROTECTED]>

> every time we come across a case where complexity is increased by 
> considering how to use site-local concurrently with global addresses (my 
> favourite list starts with source address selection and DNS lookup, but 
> does not end there.....), 

1. There is NO PROBLEM with source address selection. 

 - if your destination is site local, your source address is
   site-local,

 - if your destination is global, your source is global,

If there are any changes in source address selection, I would
actually wish that it is always required that source source and
destination are always same scope. (Now it is apparently allowed to
use higher scope source address).

Because IPv6 has link local addresses, the source address selection
machinery with scopes must be done anyway, and supporting site locals
does not bring in any extra complexities.


2. I accept that DNS-issue needs some discussion and defintion.

My view on this is that you need the "scoped DNS" architecture, which
can be seens as extension to "two-faced DNS". You can have
  
 a. global DNS service (the current)
 b. site local DNS service
 c. link local DNS service

and you have the normal search order policy inside your resolver, for
example

   1. look hosts file
   2. look global dns service
   3. look site local service
   4. look link local service (LLMNR)

the proces stops when answer is found from any level (e.g. if global
service gives positive answer, site and link local are not
queried). "Not found" answer is trickier: continue to next level or
not? (probably needs to be somewhat configurable).

Not all levels need to be present always.

---

Stacks have already been implemented and delivered with support for
site locals. The support stays in, and it's up to users and site
admins to decide whether they are used or not.
 
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