Xen users - Apr 2009 - Problem with Xen bridge on Debian Lenny

Hello Xen-Users,

I am trying to make Xen work on Debian Lenny and I''m getting pretty
desperate... I am trying to install Xen on a battery of Dell Optiplex''s
755.
I am using Debian Lenny because I am rather familiar with it and Debian Etch
doesn''t work (no network drivers and no CD-ROM drivers).

I have installed Xen many times on Debian Etch with binaries and source and
it has worked wonderfully. But today''s matter is quite different.

I have tried installing Xen 3.2.1 from Debian repos and Xen 3.3.1 from
source. Both installs go smoothly. Yet the problem is the same on both.

Now the killer problem... When I boot into Xen everything works fine
except... the networking. The interface that was recognized as eth0 when I
was with Debian (no Xen) now become eth1 for some unknown reason. The line
responsible for this is the following :

*tpxen kernel: udev: renamed network interface eth0 to eth1*

So in Xen I have eth1. I enabled *(network-script network-bridge) *as well
as *(vif-script vif-bridge)*. No bridge appears and no vif interfaces, no
nothing except eth1 and lo.

My dom0 has network connectivity but when I start my VM they do not start
correctly since Xen cannot find the bridge. When I do *brctl show*, the
bridge does not appear either. Nothing about the bridge in the dmesg ou in
the kernel messages.

There is something in the xend.log but I don''t know what it means:

*INFO (XendNetwork:114) Not recreating missing unmanaged network xenbr0*

Could anyone help me out with this ?

Thank you very much in advance for your help,

Antoine Benkemoun


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Bonjour Antoine,

Antoine Benkemoun wrote:
> Now the killer problem... When I boot into Xen everything works fine 
> except... the networking. The interface that was recognized as eth0 when 
> I was with Debian (no Xen) now become eth1 for some unknown reason. The 
> line responsible for this is the following :
> 
> /tpxen kernel: udev: renamed network interface eth0 to eth1/
I guess that xend does reconfigure your network during the boot sequence 
and the new interface might be detected as different. You can probably 
deal with this in:
/etc/udev/rules.d/70-persistent-net.rules
> So in Xen I have eth1. I enabled /(network-script network-bridge) /as 
> well as /(vif-script vif-bridge)/. No bridge appears and no vif 
> interfaces, no nothing except eth1 and lo.
I personnaly prefer not to change anything in xend-config.sxw in order 
to ease future dist-upgrade.

Actually, there is -- in my knowledges -- at least two ways to get the 
domUs bridged to the dom0 interface with Debian. The one you describe 
(which I faced many times problems with) is one of them. Another one is 
to let xend-config as is it (aka /(network-script network-dummy)/ and 
/(vif-script vif-bridge)/) and to configure the bridges at the network 
level. Here is my /etc/network/interface:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto xenbr0
iface xenbr0 inet static
         address 192.168.98.96
         netmask 255.255.255.0
         network 192.168.98.0
         gateway 192.168.98.1
         bridge_ports eth0
         bridge_stp off
         bridge_maxwait 0
         # dns-* options are implemented by the resolvconf package, if 
installed
         dns-nameservers 192.168.97.3 192.168.97.9
         dns-search my-domain.tld


When you boot your dom0, it will have xenbr0 instead of eth0. DomUs will 
work as usual and the "eth0" of each domU will be bridged to xenbr0. 
This is *IMO* the best way to configure Xen in bridge-mode on Debian.

HTH

Regards,
-- 
Olivier Le Cam

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Thank you very much for your help.

For the network interface renaming, I checked out that file. If i deleted it
gets recreated and if I comment out the line that renames my interface, it
adds the line to rename it.

I''ll try out the method you are mentionning as it sounds really good.

Antoine Benkemoun

On Wed, Apr 22, 2009 at 12:44 PM, Olivier Le Cam <
Olivier.LeCam@crdp.ac-versailles.fr> wrote:
> Bonjour Antoine,
>
> Antoine Benkemoun wrote:
>
>> Now the killer problem... When I boot into Xen everything works fine
>> except... the networking. The interface that was recognized as eth0
when I
>> was with Debian (no Xen) now become eth1 for some unknown reason. The
line
>> responsible for this is the following :
>>
>> /tpxen kernel: udev: renamed network interface eth0 to eth1/
>>
>
> I guess that xend does reconfigure your network during the boot sequence
> and the new interface might be detected as different. You can probably deal
> with this in:
> /etc/udev/rules.d/70-persistent-net.rules
>
>  So in Xen I have eth1. I enabled /(network-script network-bridge) /as well
>> as /(vif-script vif-bridge)/. No bridge appears and no vif interfaces,
no
>> nothing except eth1 and lo.
>>
>
> I personnaly prefer not to change anything in xend-config.sxw in order to
> ease future dist-upgrade.
>
> Actually, there is -- in my knowledges -- at least two ways to get the
> domUs bridged to the dom0 interface with Debian. The one you describe
(which
> I faced many times problems with) is one of them. Another one is to let
> xend-config as is it (aka /(network-script network-dummy)/ and /(vif-script
> vif-bridge)/) and to configure the bridges at the network level. Here is my
> /etc/network/interface:
>
> # This file describes the network interfaces available on your system
> # and how to activate them. For more information, see interfaces(5).
>
> # The loopback network interface
> auto lo
> iface lo inet loopback
>
> # The primary network interface
> auto xenbr0
> iface xenbr0 inet static
>        address 192.168.98.96
>        netmask 255.255.255.0
>        network 192.168.98.0
>        gateway 192.168.98.1
>        bridge_ports eth0
>        bridge_stp off
>        bridge_maxwait 0
>        # dns-* options are implemented by the resolvconf package, if
> installed
>        dns-nameservers 192.168.97.3 192.168.97.9
>        dns-search my-domain.tld
>
>
> When you boot your dom0, it will have xenbr0 instead of eth0. DomUs will
> work as usual and the "eth0" of each domU will be bridged to
xenbr0. This is
> *IMO* the best way to configure Xen in bridge-mode on Debian.
>
> HTH
>
> Regards,
> --
> Olivier Le Cam
>

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