Re: Xen3 + VLANs + multiple DOM0s cause loss of connectivity?

[Johan Ihren <johani%autonomica.se@localhost>]

Hi Pavel,

On 26 Jan 2008, at 14:04, Pavel Cahyna wrote:

> On Thu, Jan 24, 2008 at 12:26:52PM +0100, Johan Ihren wrote:
> > Hi,
> >
> > I have a complex Xen setup that utilizes VLANs to instantiate a  
> > virtual
> > network topology on top of a physical infrastructure with several  
> > DOM0s
> > connected through a single physical switch.
> >
> > This has worked just fine with Xen2 for a long time. But now I've  
> > upgraded
> > to Xen3 and unfortunately I've started having severe problems.
> >
> > This doesn't seem to work:
> >
> > * Two DOMUs running on separate DOM0s, communicating over IPv6  
> > inside a VLAN.
> >  I.e. a setup like the following doesn't work for me:
> >
> >        domu1# ifconfig vlan0 create
> >        domu1# ifconfig vlan0 vlan 10 vlanif xennet0
> >        domu1# ifconfig vlan0 inet6 2001:1:1::1 prefixlen 32
> >        domu2# ifconfig vlan0 create
> >        domu2# ifconfig vlan0 vlan 10 vlanif xennet0
> >        domu2# ifconfig vlan0 inet6 2001:1:1::2 prefixlen 32
> >        domu2# ping6 2001:1:1::1                **** Doesn't work
> >
> >  Note that if the DOMUs are on the *same* DOM0 then everything is ok.
> >
> > * Two DOMUs running on separate DOM0s, communicating over IPv4  
> > inside a VLAN
> >  where at least one of the DOMUs is using *several* IP v4 addresses  
> > (i.e.
> >  IP aliases) on the same interface.
> >
> >        domu1# ifconfig vlan0 create
> >        domu1# ifconfig vlan0 vlan 10 vlanif xennet0
> >        domu1# ifconfig vlan0 inet 10.1.0.1/24
> >        domu1# ifconfig vlan0 inet 10.1.0.2/24 alias
> >        domu2# ifconfig vlan0 create
> >        domu2# ifconfig vlan0 vlan 10 vlanif xennet0
> >        domu2# ifconfig vlan0 inet 10.1.0.10/24
> >        domu2# ping -n 10.1.0.1                 **** May work
> >        domu2# ping -n 10.1.0.2                 **** Usually doesn't  
> > work
>
> You should also show the configuration of network in the dom0s and the
> type of their network cards.

Sorry. Should have thought about that.

This happens across all systems I've tested this on and that includes  
wm(4), fxp(4), bge(4) and nfe(4). The DOM0s basically have no network  
config, i.e. I cannot use VLANs on them to communicate with my DOMUs  
(because I'm aware since a long time that simply doesn't work for a  
DOM0) and hence their config is typically just

dom0-1# ifconfig wm0 inet 192.168.100.1/22
dom0-1# ifconfig bridge0 create
dom0-1# brconfig bridge0 add wm0
dom0-2# ifconfig wm0 inet 192.168.100.2/22
dom0-2# ifconfig bridge0 create
dom0-2# brconfig bridge0 add wm0

and then the two interfaces are connected through a physical switch.

Johan