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.
Regards,
Dan.
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