----- Original Message -----
> From: "Dan Kenigsberg" <dan...@redhat.com>
> To: "Antoni Segura Puimedon" <asegu...@redhat.com>, "Igor Lvovsky" 
> <ilvov...@redhat.com>
> Cc: "Mark Wu" <wu...@linux.vnet.ibm.com>, vdsm-devel@lists.fedorahosted.org
> Sent: Tuesday, December 11, 2012 7:44:05 PM
> Subject: Re: [vdsm] Fwd: Bonding, bridges and ifcfg
> 
> On Tue, Dec 11, 2012 at 11:42:49AM -0500, Antoni Segura Puimedon
> wrote:
> > 
> > 
> > ----- Original Message -----
> > > From: "Mark Wu" <wu...@linux.vnet.ibm.com>
> > > To: "Antoni Segura Puimedon" <asegu...@redhat.com>
> > > Cc: vdsm-devel@lists.fedorahosted.org
> > > Sent: Tuesday, December 11, 2012 6:42:45 AM
> > > Subject: Re: [vdsm] Fwd: Bonding, bridges and ifcfg
> > > 
> > > On 12/10/2012 08:24 PM, Antoni Segura Puimedon wrote:
> > > > Hello everybody,
> > > >
> > > > We found some unexpected behavior with bonds and we'd like to
> > > > discuss it.
> > > > Please, read the forwarded messages.
> > > >
> > > > Best,
> > > >
> > > > Toni
> > > >
> > > > ----- Forwarded Message -----
> > > >> From: "Dan Kenigsberg" <dan...@redhat.com>
> > > >> To: "Antoni Segura Puimedon" <asegu...@redhat.com>
> > > >> Cc: "Livnat Peer" <lp...@redhat.com>, "Igor Lvovsky"
> > > >> <ilvov...@redhat.com>
> > > >> Sent: Monday, December 10, 2012 1:03:48 PM
> > > >> Subject: Re: Bonding, ifcfg and luck
> > > >>
> > > >> On Mon, Dec 10, 2012 at 06:47:58AM -0500, Antoni Segura
> > > >> Puimedon
> > > >> wrote:
> > > >>> Hi all,
> > > >>>
> > > >>> I discussed this briefly with Livnat over the phone and
> > > >>> mentioned
> > > >>> it to Dan.
> > > >>> The issue that we have is that, if I understand correctly our
> > > >>> current
> > > >>> configNetwork, it could very well be that it works by means
> > > >>> of
> > > >>> good
> > > >>> design with
> > > >>> a side-dish of luck.
> > > >>>
> > > >>> I'll explain myself:
> > > >>> By design, as documented in
> > > >>> http://www.kernel.org/doc/Documentation/networking/bonding.txt:
> > > >>> "All slaves of bond0 have the same MAC address (HWaddr) as
> > > >>> bond0
> > > >>> for all modes
> > > >>> except TLB and ALB that require a unique MAC address for each
> > > >>> slave."
> > > >>>
> > > >>> Thus, all operations on the slave interfaces after they are
> > > >>> added
> > > >>> to the bond
> > > >>> (except on TLB and ALB modes) that rely on ifcfg will fail
> > > >>> with a
> > > >>> message like:
> > > >>> "Device eth3 has different MAC address than expected,
> > > >>> ignoring.",
> > > >>> and no
> > > >>> ifup/ifdown will be performed.
> > > >>>
> > > >>> Currently, we were not noticing this, because we were
> > > >>> ignoring
> > > >>> completely
> > > >>> errors in ifdown and ifup, but
> > > >>> http://gerrit.ovirt.org/#/c/8415/
> > > >>> shed light on
> > > >>> the matter. As you can see in the following example (bonding
> > > >>> mode
> > > >>> 4) the
> > > >>> behavior is just as documented:
> > > >>>
> > > >>>      [root@rhel64 ~]# cat /sys/class/net/eth*/address
> > > >>>      52:54:00:a2:b4:50
> > > >>>      52:54:00:3f:9b:28
> > > >>>      52:54:00:51:50:49
> > > >>>      52:54:00:ac:32:1b <-----------------
> > > >>>      [root@rhel64 ~]# echo "+eth2" >
> > > >>>      /sys/class/net/bond0/bonding/slaves
> > > >>>      [root@rhel64 ~]# echo "+eth3" >
> > > >>>      /sys/class/net/bond0/bonding/slaves
> > > >>>      [root@rhel64 ~]# cat /sys/class/net/eth*/address
> > > >>>      52:54:00:a2:b4:50
> > > >>>      52:54:00:3f:9b:28
> > > >>>      52:54:00:51:50:49
> > > >>>      52:54:00:51:50:49 <-----------------
> > > >>>      [root@rhel64 ~]# echo "-eth3" >
> > > >>>      /sys/class/net/bond0/bonding/slaves
> > > >>>      [root@rhel64 ~]# cat /sys/class/net/eth*/address
> > > >>>      52:54:00:a2:b4:50
> > > >>>      52:54:00:3f:9b:28
> > > >>>      52:54:00:51:50:49
> > > >>>      52:54:00:ac:32:1b <-----------------
> > > >>>
> > > >>> Obviously, this means that, for example, when we add a bridge
> > > >>> on
> > > >>> top of a bond,
> > > >>> the ifdown, ifup of the bond slaves will be completely
> > > >>> fruitless
> > > >>> (although
> > > >>> luckily that doesn't prevent them from working).
> > > >>
> > > >> Sorry, thi is not obvious to me.
> > > >> When we change something in a nic, we first take it down
> > > >> (which
> > > >> break
> > > >> it
> > > >> away from the bond), change it, and then take it up again (and
> > > >> back
> > > >> to
> > > >> the bond).
> > > >>
> > > >> I did not understand which flow of configuration leads us to
> > > >> the
> > > >> "unexpected mac" error. I hope that we can circumvent it.
> > > I get the same question.  The warning message should be only seen
> > > when
> > > you run ifup on bonding or its slave, which is already up,
> > > otherwise
> > > the slave nic's mac address should hold its own permanent mac
> > > address.
> > > If the bonding is down before, you shouldn't see this message
> > > because the nic is not enslaved.
> > 
> > It's easy enough to reproduce. To the current HEAD do:
> > 
> > vdsClient 0 addNetwork bridge=kaboom bonding=bond0 nics=eth1,eth2
> > bridged=True
> > 
> > Go to /var/log/vdsm/vdsm.log and you'll see that:
> > http://pastebin.com/09eRNzv6
> > 
> > On line 33 you'll see that the ifup of eth2 is FAILED.
> 
> Ok, I think this is a bug in the sequence of our ifup'ing. Reviewing
> ifup-eth I see that in its "if bonding device" stanza there's
> 
> if [ "$ISALIAS" = no ] && is_bonding_device ${DEVICE} ; then
> ...
>     for device in $(LANG=C egrep -l
>     "^[[:space:]]*MASTER=\"?${DEVICE}\"?[[:space:]]*$"
>     /etc/sysconfig/network-scripts/ifcfg-*) ; do
>             is_ignored_file "$device" && continue
>             /sbin/ifup ${device##*/}
> ...
> 
> meaning that if we prepare ifcfg-eth* files on time, the interfaces
> would be
> brought up by means of `ifup bond??`; and it seems that there is no
> need
> for a specific `ifup eth0` at all.

Yes this is the same conclusion I arrived when I looked at it earlier,
Basically on bonding case we can just not do the ifups of the underlying
devices.
> 
> Regards,
> Dan.
> 
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