Re: you have running code ... I-D Action: draft-ietf-6man-ipv6only-flag-03.txt

["Bjoern A. Zeeb" <[e-mail]>]

On 31 Oct 2018, at 9:24, Nick Hilliard wrote:

> Job Snijders wrote on 30/10/2018 22:27:
>> Can you (or others running FreeBSD EXPERIMENTAL) share reports on how
>> this pans out in practise?
> Looking at the code, it acts by blocking outbound ipv4 frames from 
> being transmitted on ethernet interfaces.

and wifi and all other kinds that use the common code.  Yes.

> This would mean - for example - that if there were a default route 
> already configured on the receiving device, any userland code 
> attempting to use ipv4 services would block until ARP times out for 
> the default route (default 20 minutes on freebsd).

That would have to be a manual configuration as on an IPv6-only link you 
would not have that at the time the flag turns up; otherwise it is a one 
time event and the admins  could do a better job.

And no an app wouldn’t block; it gets an immediate EAFNOTSUPPORT when 
it tries to send something and can got into normal error handling as for 
any socket code, try another address, or core dump if it’s that kind 
of software quality.

The point is: the noise is contained and not spread.

/bz