netdev - Re: bonding and IPv6 "doesn't work"?

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Message-ID: <4E1C756C.2010700@wpkg.org>
Date:	Tue, 12 Jul 2011 18:25:16 +0200
From:	Tomasz Chmielewski <mangoo@...g.org>
To:	David Lamparter <equinox@...c24.net>
CC:	netdev@...r.kernel.org
Subject: Re: bonding and IPv6 "doesn't work"?

On 12.07.2011 18:14, David Lamparter wrote:
> On Tue, Jul 12, 2011 at 06:05:41PM +0200, Tomasz Chmielewski wrote:
>> I make a bond0 of two interfaces, eth0 and eth1.
>
> What kind of device do you have on the other side of those links?

It's a virtual machine.
So, a bridge of the host.

I know it doesn't make much sense to set up bonding in a virtual 
machine, but I'm trying to determine what possible problems I might have 
in a production environment (and got stuck at the very beginning).

IPv4 bonding works fine in this setup.

>> bond0: IPv6 duplicate address 2a01:4f8:120:14c4::1247 detected!
> [...]
>> However if I start bonding with just one interface, add IPv6 address to
>> it, then use ifenslave to add a second interface, I'm able to reach the
>> hosts in the internet.
>
> Yeah, when you add the IPv6 address, IPv6 ND does its job and announces
> your presence/does DAD.

Shouldn't this disable DAD? Or am I confusing something here?

net.ipv6.conf.eth0.accept_dad = 0
net.ipv6.conf.eth1.accept_dad = 0

> Your bonding peer is probably looping those
> packets back on the other link, most likely because...
>
>> Bonding Mode: load balancing (round-robin)
>
> ... most likely because you maybe have a switch on the other side, and
> that switch expects you to do 802.3ad?

It's a virtual machine, so the host shouldn't know or care much about 
802.3ad (I think!).

-- 
Tomasz Chmielewski
http://wpkg.org
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