RE: address selection and DHCPv6

["Durand, Alain" <Alain_Durand at cable.comcast.com>]

I like your rule7bis algorithm.
When RFC3484 was discussed, it was clear that it will need to be
revisited
over time to cover new types of addresses or new use cases.

   - Alain.


> -----Original Message-----
> From: James Carlson [mailto:james.d.carlson at sun.com] 
> Sent: Tuesday, October 24, 2006 3:52 PM
> To: ipv6 at ietf.org
> Subject: address selection and DHCPv6
> 
> I've done quite a bit of searching over the archives and over 
> various web resources, but I haven't seen this issue 
> addressed directly.
> Apologies if I've just missed it.
> 
> RFC 3484 ("Default Address Selection for Internet Protocol version 6
> (IPv6)") section 5 gives a set of ordered comparisons for 
> source address selection.  However, missing from this list is 
> a distinction implied by RFCs 2461 and 2462: some systems may 
> have a mix of addresses acquired by stateless address 
> autoconfiguration, stateful
> (DHCPv6) configuration, and manual addressing.  How are these 
> distinguished?
> 
> Rule 7 does address the temporary (RFC 3041) addresses, but 
> what about these other flavors of addresses?  Are they 
> distinguished only by scope?
> 
> Was this issue addressed and intentionally omitted from the 
> RFC?  (If so, I don't see it in the archives.)
> 
> I suspect that some clients may need to distinguish among the 
> various flavors here.  I'd suggest amending Rule 7 to read:
> 
>    Rule 7:  Prefer stable, public addresses.
>    If SA is a manually-configured address and SB is automatic or
>    temporary, then prefer SA.  If SA is automatically configured via
>    stateful (DHCPv6) methods and SB is automatically configured via
>    stateless methods or temporary, then prefer SA.  If SA is
>    automatically configured via stateless methods and SB is temporary,
>    prefer SA.
> 
>    Similarly, if SB is a manually-configured address and SA is not,
>    then prefer SB.  If SB is stateful and SA is stateless or
>    temporary, prefer SB.  If SB is stateless and SA is temporary,
>    prefer SB.
> 
>    When the application has the "prefer temporary address" flag
>    enabled, all temporary addresses are (within this rule) elevated in
>    preference above manually-configured addresses.  The other
>    preferences are unaltered.  (In other words, the preference order
>    with this flag set becomes temporary first, then manual, stateful,
>    and stateless last.)
> 
> ... or, to simplify, defining a "stability_of_address(A)" 
> function that can work here.
> 
> -- 
> James Carlson, KISS Network                    
> <james.d.carlson at sun.com>
> Sun Microsystems / 1 Network Drive         71.232W   Vox +1 
> 781 442 2084
> MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 
> 781 442 1677
> 
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