Re: [Xen-users] bonding + VLANs -> Oops/panic, no VLAN on 100 Mbit cards [SOLVED]

[Tomasz Chmielewski <mangoo@xxxxxxxx>]

Fajar A. Nugraha schrieb:
> Tomasz Chmielewski wrote:
> > As the issue concerns both the -user (configuration) and -devel
> > (OOPS), I'm sending this message to both lists.
> >
> > Some time ago I complained about two problems:
> >
> > - VLANs are not working on machines with 100 Mbit cards
> > - I get a kernel Oops (sometimes panic) when I try to use bonding and
> > VLANs with Xen
> >
> >
> > The root of the issue is the same in both cases: VLAN interfaces must
> > *not* be brought up before we start our Xen network scripts.
> And why not?
Because then, either bonding doesn't work with VLANs, or VLANs don't 
work with 100 Mbit cards...

> I've been using vlan interfaces with xen since the days of xen-2.
> Then again, I don't use xend's network-bridge to create xenbr0. I use
> RedHat's network config to craete the necessary vlans and assign each to
> their own bridge.
>
> > So have four cases with Xen:
> >
> > 1. Bonding + VLAN leads to an Oops
> > 2. Bonding + VLAN works
> I haven't been able to get bonding to work reliably though,
> I doubt it would work as expected anyway, since the only way to get
> bonding and vlan in domU is to detect line status (which would be rather
> useless if the network problem happens anywhere other than the switch).
No - I'm setting up bonding in dom0. I doubt setting up bonding within 
domU would make much sense...
But in dom0, it works reliably.

Certainly, the machine shouldn't Oops/panic as a result of network setup 
- and it's a bug either in Xen, or in the fact that Xen does with 
networking - which does something that "bonding" driver doesn't expect.

> > 3. VLANs don't work with 100 Mbit cards
> > 4. VLANs work with 100 Mbit cards
> In my experince the problem comes from network card drivers. Some
> boradcom network cards on Dell servers wouldn't work with xen-3.0.2 (or
> to be more specific, the kernel that comes with xen-3.0.2) but works
> with xen-3.0.4.
> > I use network-bridge script shipped with Xen 3.1.
> My advice :
> - Dont't use network-bridge script. Change the entry on xend-config.sxp
> from network-bridge to /bin/true
> - Don't use bonding in dom0
Why not? It's needed for failover.


> - It will help A LOT if you have at least two interfaces on dom0: one
> for dom0 management, one (or more) for domU's traffic.
True, but that's not what bonding was invented for.


> - Create vlans and bridges in dom0 using your distro's network config.
> - If you need bonding and have more than two dom0 interface handling
> domU's traffic, do the bonding in domU.
Doesn't make much sense to me to do bonding in domU.
What if you want to live migrate the guest to a host which doesn't have 
two cards?
Also you wrote it earlier ("I doubt it would work as expected anyway, 
since the only way to get bonding and vlan in domU is to detect line 
status (which would be rather useless if the network problem happens 
anywhere other than the switch)") - so I'm not sure what you mean.

--
Tomasz Chmielewski
http://wpkg.org

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