Re: [Xen-users] Bonding â dom0 or dom1 ? and why is vif1.1 missing in DomU?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I have a machine with two different nics (sis900 and dmfe).
> I am trying bonding in Xen. (on FC6, intel x386, para virtualization).
>
> In the past  I did successfully configured and used bonding on non-Xen
> Linux machines.
>
> I saw some posts in this list and in other sites regarding Xen
> bonding, but I am a little bewildered
> so I want to verify something:
>
> I am using the default /etc/xen/xend-config.sxp config file, which
> means I am using
> bridging (ifconfig can show xenbr0).
>
> When booting into domain 0 both nics are recognized (as I can see from
> dmesg), also "ifconfig -a" from  dom0 shows eth0 and eth1.

The default config bridges eth0, so you'll need to tweak things a bit to get 
both eth0 and eth1 working as a bonding device on that bridge...

> Now when I boot into domain U , "ifconfig -a" shows only eth0.
> /etc/modprobe.conf has a line saying "alias eth0 xennet" (but eth1
> does not appear in /etc/modprobe.conf).

That's fine - domUs just see a virtual ethernet device.  There's probably not 
much point in exposing the two real ethernet devices to guests.  If you 
configure bonding in dom0 you should be able to hide this detail completely 
from the guests - they'll just see their virtual network going faster.

> Now I have two questions:
> 1)I want to configure bonding through the initscripts
> (namely , create /etc/sysconfig/network-scripts/ifcfg-bond0 and add
> MASTER/SLAVE entries in /etc/sysconfig/network-scripts/ifcfg-eth0 and
> /etc/sysconfig/network-scripts/ifcfg-eth1 ,
> etc.) Where should I do it ? In dom 0 ? or in dom U ? I saw somewhere
> in xen-user mailing list that it should be done in dom U ; but as I
> said, ifconfig -a does not show eth1 in dom U .
> Any tips or guidance as to what should I do or pointers to bonding on
> Xen that worked for you will be helpful.

If you edit the config you could pass it through, but I think it would be 
better to try and do it in dom0 so that the guests don't need to be configured 
individually.

>
> 2)
>  After boot of domain U , I ran ifconfig -a ***in domain 0***, and I
> saw only ONE vif1.* instance (vif1.0) I expected to see also vif1.1
> for the second nic.
> The XenNetworking wiki page says : "If you create multiple network
> interfaces for a domU, it's ends will be eth0, eth1, etc, whereas the
> dom0 end will be vif<id#>.0, vif<id#>.1, etc."
> (http://wiki.xensource.com/xenwiki/XenNetworking). Did I misunderstood
> something ?
> Am I wrong somewhere?

Unless you explicitly specified two virtual network interfaces in the domain's 
config, you won't get two appearing there.  This is probably fine for you;

I'd be inclined to try bonding eth0 and eth1 in the normal way in dom0 then 
arranging for the bonding device to be added to the bridge instead of either 
eth0 or eth1...  I'm not sure if there would be any nasty interactions with 
the bridging and bonding code here.  If you have any problems, you could also 
try using a routed rather than bridged setup.

Solutions to this will probably involve some fiddling with the dom0 config 
and / or the networking setup scripts used to configure vifs.

Hope this clears up some things for you!

Cheers,
Mark


-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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