On 04  Mar 2011, at 13:10 , Mikael Abrahamsson wrote:
> SLAAC is by definion host-controlled.  

Existing RA flags control whether SLAAC is allowed
or DHCP is required, so this proposal is not a significant 
architectural change either to IPv6 or to RA flag use.

Any proposal to the WG might or might not meet one's 
personal definition of "sufficient need to justify 
changing/adding specs" -- I gather you think it does not 
meet your definition of sufficient need (jhw and some others 
seem to have a similar view :-).

> You use the term "audit" in a way I don't really understand 

At least for these users, "audit" has a meaning quite similar
to the ordinary business usage (e.g. when a CPA or Chartered Accountant 
audits a public firm's financial records).  

In many countries, public firms aren't required to have 
flawless financial records, merely "good enough" (reportedly
this is often expressed as a sufficient "confidence interval").

> If you want to be sure who did what when, you need centrally
> controlled IPv6 address hand-out plus something that makes sure
> user can't source any other traffic, such as the SAVI-WG
> functionality IP/MAC address verification schemes.

My apologies if I was unclear.  
This is NOT access-control, but instead merely audit.  

As with audits of financial records, perfection is not required,
but a certain confidence interval IS desired/required/needed.

As near as I can  tell, different user organisations target 
different confidence intervals.  

If a significant number of systems use the "privacy-mode" addressing, 
that confidence interval is not achievable.  If a tiny number use 
that mode, a large deployment reportedly can meet the required 
confidence interval.

Again, this is audit, not access control, and absolute perfection
is not a requirement.

> If you need to know what host had what IP address at what time,
> disallow SLAAC and run DHCPv6.


I'm told that some users already are using implementation-specific
configuration mechanisms (e.g. apparently a MS-Windows "Registry"
setting) that allow SLAAC, but disallow the privacy extension.

I'm further told that when configured to disable "privacy-mode",
such hosts then create the EUI-64 based on some MAC address 
in the host.  

I'm told that outcome is quite sufficient for audit purposes, 
but is expensive and tedious to deploy -- primarily because
the configuration is platform-dependent.

This proposal would provide an platform-independent way 
to configure that sort of knob, which knob apparently exists 
now within an interesting number of deployed end systems. 

I hope the situation is more clear now.  Thanks for your
follow-up questions and comments.

Cheers,

Ran

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