Re: Running code (Was: I-D Action: draft-ietf-6man-ipv6only-flag-03.txt)

[Simon Hobson <[e-mail]>]

Mark Smith <[e-mail]> wrote:

>> > Which says, I have no peripherals configured which require IPv4
>> 
>> how do you know in advance that there are no peripherals that the user might want to connect to which are IPv4 only ?
> 
> Because the network operator has actively asserted that there aren't, by actively choosing to set this flag.

I agree - that would be the case using the flag. But Albert (to whom the question was asked) asserts that heuristics such as "IPv6 appears to work and we have no active IPv4 connections" is sufficient to determine whether or not to enable IPv4.

> If any such devices attached to an IPv6 only link, they shouldn't have been, and it is a network connection policy violation for the link. They'll fail to work and should fail to work, because they don't talk IPv6.

Yes

> If IPv4 only devices can be legitimately connected to this link, then clearly it isn't an IPv6 Only link, and the flag shouldn't be set.
> 
> We're getting into trying to prevent insanity territory with these sorts of corner cases. 

I agree. Setting the flag where IPv4 is expected to continue working would be a configuration error - and one that the network admin can fix by unsetting the flag.
Doing it by heuristics is prone to soft errors that would be hard to diagnose and harder to fix. But I don't seem to be getting through to Albert on this one.