[Devel] Re: [Users] 2.6.18-ovz028test015 and 2.6.18-ovz028test018 break IPv6

Kirill Korotaev dev at sw.ru
Mon Mar 5 00:38:27 PST 2007


Michael,

Can you please check that the patch from bug
http://bugzilla.openvz.org/show_bug.cgi?id=476
helps you?

Thanks,
Kirill


> Hello,
> 
> 	Introduction...  I've been on the users list for a while and just
> joined the developers list.  Excuse the cross post but I'm not sure
> which would be most appropriate.
> 
> 	I work extensively with IPv6.  All of my devices are configured for
> IPv6 and I actively participate in the global IPv6 network and have for
> over 5 years.  I'm a member of the North American v6 Task Force,
> NAv6TF.org.  My name servers, ntp servers, smtp servers, and web servers
> all show active IPv6 traffic and have for years.  I'm also a big user of
> VMware and I'm also the author of an IPv6 paper that's up on their site
> somewhere.
> 
> 	So, I'll prefix this with a bit of a rant.
> 
> 	<Rant>
> 
> 	I don't use venet.  The way it's implemented, especially vis-a-vis
> IPv6, it makes no sense to me at all.  the venet0 devices have no
> hardware / mac layer addresses so how is IPv6 neighbor discovery and
> autoconfiguration protocols suppose to work?  These are really
> fundamental to the nature of IPv6 and, unless you want to use IPv6
> purely like it just IPv4 with fat addresses (which it is NOT) and live
> entirely in an IPv4 mind-think cocoon when working with IPv6, how can
> you expect this to work with fully implemented IPv6?
> 
> 	The bridged networking of the veth devices seem to be the only viable
> way to deal with this.  I HAVE tried using venet for IPv6 and failed
> miserably.
> 
> 	This is also how I deal with IPv6 on VMware.  I never use the local
> networking (host local or NAT) devices and only use the bridged devices
> there.  In the case of VMware, the bridged devices are the default and
> you can add the routed or nat'ed devices.  That makes a lot more sense
> to me.
> 
> 	So IPv6 HAS to work for me.  Consequently, I have to work with
> everything running over the veth devices.  The venet devices just do not
> cut it at all with IPv6, so are totally useless to me for both IPv4 as
> well as IPv6 (why split the network two ways).
> 
> 	Funny thing is, if you "turn on" IPv6 in the vz configuration files, it
> dicks things up royally by trying to force IPv6 routes out through the
> venet0 interface, which can't work, and interferes with stateless
> autoconfiguration and router discovery configuration.  Leaving IPv6 off
> in the config, then it doesn't insert bogus routes and everything
> configures properly on the veth devices and IPv6 works like a charm.
> Interestingly enough, the veth devices DO get their proper link-local
> and global-unicast addresses while vnet0 sits there with not even a
> link-local address (of course - it has no mac address so how could it
> possibly have a link-local address - duh...).
> 
> 	</Rant>
> 
> 	Now...  Onto the problem.  IPv6 is working sweet with
> 2.6.18-ovz028test010 on Fedora Core 6.  It would be nice to get it up to
> the FC6 2.6.19 (soon to be the 2.6.20) rebase but that's ok for now.
> When I tried 2.6.18-ovz028test015 and subsequently 2.6.18-ovz028test018,
> I found that IPv6 was totally broken.  While all my interfaces properly
> autoconfigure on test10, stateless autoconf appears to be totally broken
> on test15 and test18 and even manual configuration doesn't work (hints
> strongly at broken neighbor discovery there).
> 
> 	This may not be an OpenVZ problem, per se, though.  Some time in the
> very later part of the 2.6.18 kernel.org release updates, a problem was
> introduced that broke IPv6.  Some patch or another caused nodes to fail
> to join the "all nodes multicast" (ff02::1) address.  This is critical
> to IPv6 router discovery and advertisement, neighbor discovery, and
> autoconfiguration.  All fall down go boom.
> 
> 	This actually wasn't "discovered" until 2.6.19 but it seems to have
> been introduced in a couple of late clicks of 2.6.18 and is not fixed in
> the kernel.org tree until 2.6.20-rc5 or so.  Fedora Core seems to have
> retrofitted the fix into the last couple of clicks of the FC6 2.6.19
> (currently 2.6.19-2911) but the stock kernel.org kernels have been
> broken in a couple of 2.6.18 releases and, AFAICT, all of the 2.6.19
> releases.
> 
> 	This is re-enforced by checking the group memberships on test010 vs
> test018 in both host and guest (netstat -g).
> 
> Host test010:
> 
> IPv6/IPv4 Group Memberships
> Interface       RefCnt Group
> --------------- ------ ---------------------
> lo              1      ff02::1
> eth0            1      ff02::fb
> eth0            1      ff02::1:ff10:f84d
> eth0            1      ff02::1
> veth0           1      ff02::fb
> veth0           2      ff02::1:ff10:f84d
> veth0           1      ff02::1
> veth1           1      ff02::fb
> veth1           1      ff02::1:ff3a:e3e2
> veth1           1      ff02::1
> veth1006.0      1      ff02::fb
> veth1006.0      1      ff02::1:ff01:6
> veth1006.0      1      ff02::1
> veth1010.1      1      ff02::fb
> veth1010.1      1      ff02::1:ff01:100a
> veth1010.1      1      ff02::1
> veth1026.0      1      ff02::fb
> veth1026.0      1      ff02::1:ff01:1a
> veth1026.0      1      ff02::1
> 
> Host test018:
> 
> IPv6/IPv4 Group Memberships
> Interface       RefCnt Group
> --------------- ------ ---------------------
> eth0            1      ff02::fb
> eth0            1      ff02::1:ff10:f84d
> veth0           1      ff02::fb
> veth0           1      ff02::1:ff10:f84d
> veth1           1      ff02::fb
> veth1           1      ff02::1:ff3a:e3e2
> veth1006.0      1      ff02::fb
> veth1006.0      1      ff02::1:ff01:6
> veth1010.1      1      ff02::fb
> veth1010.1      1      ff02::1:ff01:100a
> 
> 	Yeah, that would be a problem and is the symptoms reported on lkml.
> 
> 	Here's one of the guest systems (1006 above):
> 
> Guest 1006 test010:
> 
> IPv6/IPv4 Group Memberships
> Interface       RefCnt Group
> --------------- ------ ---------------------
> lo              1      ff02::1
> eth0            2      ff02::1:ff01:106
> eth0            1      ff02::1
> eth1            1      ff02::1:ff01:1106
> eth1            1      ff02::1
> 
> Guest 1006 test018:
> 
> IPv6/IPv4 Group Memberships
> Interface       RefCnt Group
> --------------- ------ ---------------------
> eth0            1      ff02::1:ff01:106
> eth1            1      ff02::1:ff01:1106
> 
> 	Same problem.  Missing the ff02::1 address on every interface.  Bad
> juju.
> 
> 	I suspect that test15 and test18 picked up the bad IPv6 patch and broke
> IPv6.  We need a rebase to a working kernel or a retrofit of the patch
> from 2.6.20.  I have not been able to get the oz patch to patch into the
> 2.6.19 FC6 kernels, but that would be a good place to start since they
> are no have IPv6 working.  You might examine those retrofit patches.
> Better yet would be to rebase the test series up to 2.6.20.
> 
> 	Mike
> 
> 
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> 
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