Re: [v6ops] M/O flags and PD

[Brian E Carpenter <[e-mail]>]

On 31/10/2015 21:46, Tore Anderson wrote:
> * Brian E Carpenter
> 
>> On 31/10/2015 04:24, Sander Steffann wrote:
>>
>>> I always understood this bit from RFC 3633 to mean that any host
>>> configuration flags (such as M/O) are not relevant to DHCPv6-PD:
>>> "Note that this use of DHCP is not bound to the assignment of IP
>>> addresses or other configuration information to hosts".	
>>
>> The phrase "is not bound to" is rather unclear, don't you think? It
>> neither says nor implies that routers are thereby exempt from issuing
>> correct RAs.
> 
> Agreed.
> 
> Also, note that RFC 3633 did *not* update RFCs 2461/2462, which at the
> time defined the meaning of the O/M flags to be essentially the same as
> what RFC 4861 defines them to be today.
> 
>> Even if you accept that, in the case that you *don't* know that such
>> information is available, you physically cannot set the M or O flag.
>> So in the real world, a node that is interested in IA_PD had better
>> go fishing for it, whatever the MO bits say. So I retract all the if
>> statements in the pseudocode that I sent. The only robust
>> implementation is one that always looks for DHCPv6 information.
> 
> That might indeed be the case - but it's not what the standards are
> currently telling the implementers to do. Furthermore, accepting this
> would mean that the M/O flags are essentially pointless. In that case,
> deprecating the flags would be the logical thing to do.

I know. It's a bit depressing.

> (You explicitly called out IA_PD, but as your argument applies equally
> well to any other DHCPv6 option I'm going to assume you meant IA_PD
> just as an example.)

Yes, although it's the example that led to this thread.

  Brian