On Mon, 13 Nov 2017 23:52:26 +0900 Maciej Żenczykowski <m...@google.com> wrote:
> >> Should we consider rolling back the patch that caused this? > >> "accept_dad = 1" is the proper IETF-expected default behaviour. > >> > >> Alternatively, if we really want to make all, default, and ifname > >> useful perhaps we need to investigate a tristate option (for currently > >> boolean values, at least). -1 could mean no preference, for example. > > > > I haven't checked how ugly it would be, yet. But another way to restore > > the previous behaviour, while keeping the new functionality, would be > > to keep the global default as 1 and instead set the per-interface > > accept_dad default value to 0. What do you think? > > The default out-of-the-box behaviour should definitely be to do DAD. > > You can achieve this in 4 ways: > > [A] all=1, default=1, AND --> the OLD pre-patch behaviour Old pre-patch behaviour simply ignored the 'all' value though. > [B] all=1, default=1, OR --> the NEW post-patch behaviour - problematic > [C] all=1, default=0, OR --> problematic for same reason: iface=0 is a no-op But this way you could still globally disable DAD, starting from default values, by simply setting 'all' to zero, which is what Nicolas wanted. > [D] all=0, default=1, OR > > Note that: > AND == (all < 1 || interface < 1) > OR == (all < 1 && interface < 1) > > [C] requires one to set all but one interface (incl. default) to 1, > then set all=0, > just to disable a single interface's dad > > [D] is weird, because with the default already being dad enabled, there's > really > no reason to ever set all=1 > > Being able to disable either for all interfaces (via all=0) or for a > specific interface (via iface=0) seems > the most useful. > > Setting all=1, default=0, specific_interfaces=1, AND-logic also seems useful. > > Hence my vote to rollback a2d3f3e33853. We're mostly talking about 35e015e1f577 here. -- Stefano
