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

[Nick Hilliard <[e-mail]>]

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.  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).

The only part of the ipv6only discussion that was uncontroversial was 
implementation of the kernel processing side of this flag - there's very 
little to go wrong when toggling a single flag.

The problem area is how to handle the interpretation of this flag in 
userland and in the kernel, which is a much more difficult problem. 
This in turn depends on consensus in 6man about what the flag actually 
means, and there doesn't seem to be much consensus on that.

This also disregards the issue of whether the flag was either necessary 
or a good idea to start with, and nearly 700 emails into this 
discussion, the WG seems to be hopelessly divided on these issues.

Nick