Re: I-D Action: draft-ietf-6man-ipv6only-flag-03.txt

[Joel Jaeggli <[e-mail]>]

> On Oct 20, 2018, at 10:34, Ola Thoresen <[e-mail] <mailto:[e-mail]>> wrote:
> 
> On 20/10/2018 00:12, Ole Troan wrote:
> 
>> 
>> 
>> In my view, I don’t see much purpose in the bit unless it’s prescriptive. As in the last category. 
>> 
> 
> On this, we can agree. Having a flag as a "hint" does not make much sense.  You can't trust it, so you would STILL need to verify if the flag is actually telling the truth, or if it is just set - either malicious, or by mistake.  
> 
I can’t really trust (ND, RAs, ARP, DHCP, DHCPv6, MDNS). Lack of trust here extends to most of the signals one might receive in the process of bootstrapping. Of those signals some of them I accept because as part of a faustian bargain I made when attaching to the network, I actually need some of that information. The stuff that I don’t have to accept in order to achieve basic functionality I ignore.

As  case in point all the operating systems I use allow me to specify my own nameserver despite receiving such information  via DHCP/DHCPv6, doing so may come at the expense of some local funcationality but it’s worth it as far as I’m concerned.
> 
> On the other hand, I do not see how this can be a hard requirement.  Or at least I can not see operating systems actually obyeing such a flag.  IF the client administrator has configured IPv4 dhcp client settings, why should the OS trust a flag in an RA-packet more than the OS-admins configuration?
> 
> Just look at the already defined flags "O" and "M" - which are not even breaking the barrier between the IP-protocols.  I know at least a couple of implementations which will send a DHCPv6-request no matter what the RA is signaling in its M and O-flags.  And I know implementations that will not automatically send dhcp-requests no matter what flags are set in the RA-packets.  
> 
> We don't need even more flags that might or might not be ignored by the operating systems.  And which have a somewhat vague definition.
> 
And which is not absolutely necessary for bootstrapping.
> 
> We don't have a flag to tell the OS to not run DECnet, Appletalk or IPX.  We simply disable these on the clients.  And even if we had such a flag in DHCPv4 or RA, I - as an admin - would prefer the clients to not rely on such a flag, but try to get some kind of network access on any enabled network protocol in the client.
> 
> 
> 
> Rgds.
> 
> Ola (T)
> 
> 
> 
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