Re: [Xen-users] unpredictible multiple bridge behaviour.

["Chris Fanning" <christopher.fanning@xxxxxxxxx>]

Hi,

> you can work around the problem by specifying static mac addresses
> and using a bit of udev magic in domU.
Yep, that did it.
Still, I wonder why this had never been a problem before upgrade.

Thanks,
Chris.

On 3/21/07, jez <jez@xxxxxxxxxx> wrote:
> On Wed, Mar 21, 2007 at 04:41:30PM +0100, Chris Fanning wrote:
> > Hi,
> >
> > I'm using two bridges.
> > Since upgrading from 3.0-2 to 3.0-4 the vif's are randomly
> > interchanged when passed to domU.
> >
> > sometimes vif1.0 gets assigned to eth0 and vif1.1 to eth1 on domU
> > sometimes vif1.1 gets assigned to eth0 and vif1.0 to eth1 on domU
> >
> > I've tried two 'my-network-bridge' scripts.
> >
>
> Hi Chris
>
> Assuming that the output of "brctl show" (ignoring the bridge-id
> field), looks like this:
>
>    bridge name     bridge id               STP enabled     interfaces
>    xenbr0          8000.feffffffffff       no              vif0.0
>                                                            peth0
>    xenbr1          8000.feffffffffff       no              vif0.1
>                                                            peth1
>
> then you don't need to worry about the bridge building script you are
> running.
>
> I have no idea why your vif interfaces are being assigned randomly to
> eth interfaces in your domUs, but a quick test here suggests that
> you can work around the problem by specifying static mac addresses
> and using a bit of udev magic in domU. The following are instructions
> on how to acheive this.
>
> 1. In the configuration file for a domU, specify a static mac address
>    and a bridge for each interface as follows:
>
>    vif = [ 'mac=00:16:3e:00:00:11, bridge=xenbr0',
>            'mac=00:16:3e:00:00:22, bridge=xenbr1' ]
>
>    Make sure you put commas in all the right places.
>
> 2. Then inside the domU create a file called /etc/udev/vm-local.rules
>    and put the following in it:
>
>      SUBSYSTEM=="net", ATTRS{address}=="00:16:3e:00:00:11", NAME="eth0"
>      SUBSYSTEM=="net", ATTRS{address}=="00:16:3e:00:00:22", NAME="eth1"
>
> 3. Now just add a symlink to the udev rules directory so that your
>    rules file, vm-local.rules, is processed before all the other rules
>    files. The following works on my distro:
>
>       cd /etc/udev/rules.d
>       ln -s ../vm-local.rules  010_vm-local.rules
>
>    Make sure that your symlink ends in ".rules" or it will be ignored.
>
> Now, every time you start this domU, udev should ensure that eth0 and
> eth1 are always the same devices.
>
> Probably not the answer you were hoping for, but hopefully it helps.
>
> jez
>
>
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