Date: Fri, 22 Jun 2018 21:17:03 +0300 From: "Andrey V. Elsukov" <bu7cher@yandex.ru> To: freebsd-net@freebsd.org, Viktor Dukhovni <freebsd@dukhovni.org> Cc: "Bjoern A. Zeeb" <bz@FreeBSD.org>, Mark Johnston <markj@freebsd.org> Subject: Re: [PATCH]: The 6to4 stf0 interface flapping in/out of tentative in FreeBSD 11 Message-ID: <964bd37c-fe7b-1a99-6c5e-9a367cfad29f@yandex.ru> In-Reply-To: <D77DB9CD-3197-4963-95AA-CB863E0246B6@dukhovni.org> References: <CEBB4E6F-4D5F-491F-8C81-C9F81325078B@dukhovni.org> <20171106042248.GL3322@mournblade.imrryr.org> <20180622163812.GA17559@mournblade.imrryr.org> <8fe71247-a9a4-e3cb-3e4a-03852307f080@yandex.ru> <D77DB9CD-3197-4963-95AA-CB863E0246B6@dukhovni.org>
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From: "Andrey V. Elsukov" <bu7cher@yandex.ru>
To: freebsd-net@freebsd.org, Viktor Dukhovni <freebsd@dukhovni.org>
Cc: "Bjoern A. Zeeb" <bz@FreeBSD.org>, Mark Johnston <markj@freebsd.org>
Message-ID: <964bd37c-fe7b-1a99-6c5e-9a367cfad29f@yandex.ru>
Subject: Re: [PATCH]: The 6to4 stf0 interface flapping in/out of tentative in
FreeBSD 11
References: <CEBB4E6F-4D5F-491F-8C81-C9F81325078B@dukhovni.org>
<20171106042248.GL3322@mournblade.imrryr.org>
<20180622163812.GA17559@mournblade.imrryr.org>
<8fe71247-a9a4-e3cb-3e4a-03852307f080@yandex.ru>
<D77DB9CD-3197-4963-95AA-CB863E0246B6@dukhovni.org>
In-Reply-To: <D77DB9CD-3197-4963-95AA-CB863E0246B6@dukhovni.org>
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On 22.06.2018 21:08, Viktor Dukhovni wrote:
>> Your change looks reasonable due to IPv6 DAD procedure does check for
>> presence of IFF_DRV_RUNNING flag. But actually it seems the right
>> solution should be disabling DAD for if_stf(4) interface.
>> IPv6 DAD requires that given interface should be multicast capable, bu=
t
>> for if_stf(4) it is not true.
>> Will it help if you use `ifconfig stf0 inet6 no_dad` before assigning
>> IPv6 address?
>=20
> stf_up() in /etc/rc.d/stf has:
>=20
> ifconfig stf0 create >/dev/null 2>&1
> ifconfig stf0 inet6 2002:${ipv4_in_hexformat}:${stf_int=
erface_ipv6_slaid:-0}:${stf_interface_ipv6_ifid} \
> prefixlen ${stf_prefixlen}
>=20
> Are you suggesting to add the:
>=20
> ifconfig stf0 inet6 no_data
Yes, but "no_dad", not "no_data".
> right under "ifconfig stf0 create"? I'd have to find a convenient time=
to
> reboot to the stock kernel, so this will take O(12 hours) before I can =
re-test.
>=20
> Perhaps the fix should be belt-and-suspenders? Both set IFF_DRV_RUNNIN=
G
> and disable DAD automatically for lack of multicast support? Setting
> the flag bit might avoid other future issues. Avoiding needless DAD
> polling sounds sensible.
We have already one tweak for if_stf(4) in in6_ifattach(), that disables
automatic LLA creation. I think we can also add disabling DAD there.
Something like:
Index: in6_ifattach.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
--- in6_ifattach.c (revision 335361)
+++ in6_ifattach.c (working copy)
@@ -683,6 +683,7 @@ in6_ifattach(struct ifnet *ifp, struct ifnet *alti
* it is rather harmful to have one.
*/
ND_IFINFO(ifp)->flags &=3D ~ND6_IFF_AUTO_LINKLOCAL;
+ ND_IFINFO(ifp)->flags |=3D ND6_IFF_NO_DAD;
break;
default:
break;
--=20
WBR, Andrey V. Elsukov
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