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Re: [Xen-users] Xen4.4 HVM domains and routed setups

On 27/05/14 04:50, Steffen Heil (Mailinglisten) wrote:

can you elaborate a bit more on what you actually want to do? Cause I guess you 
are trying to do something I've got working with a
modified vif-nat setup and can be of help, but I would like to take the 
guesswork out of the equation first..
I have a server and I want to run several vms on it.
The server itself has one public ip (say and a whole additional 
network (say is routed to that server.

All my vms are running with a point-o-point setup, that is the vm knows it's 
own ip (say and the hosts ip ( and
routes every packet that is not for itself to the host.
The vif-route and network-route scripts are active and the configuration file 
has a line like the following:

vif = [ 'mac=00:16:3e:01:02:05,vifname=vm-fifth,ip=' ]   // works for 
linux pv

vif = [ "mac=00:16:3e:01:02:06,vifname=vm-sixth,ip=,model=e1000" ]
   // used to work for hvm on modified 4.1, does not on unmodified 4.4

ip_forwading is enabled in the host.

That works for linux clients (there are actually two already running), but I 
cannot get it to work with my windows HVM guest.
Note that that worked with xen 4.1 and modified scripts and I still have that 
server running, so I can compare network settings but I
did not find the source of the problem.

What more details can I supply?

Maybe I'm missing something here, but perhaps this will help...

On dom0, create a second bridge with no interfaces in it, perhaps something like this:
auto xenbrdomU
iface xenbrdomU inet static

In the domU config, specify this second bridge:

vif = [ 
"mac=00:16:3e:01:02:06,vifname=vm-sixth,ip=,model=e1000,bridge=xenbr5" ]

Then just use the normal bridged configuration, so all domU's are talking together on bridge xenbrdomU and dom0 is talking to the rest of the net on eth0 or whatever interface you have. You will need to enable IP forwarding, and configure routing as per normal, including the default route. All the domU's will use IP's on the subnet and have default route set to

The only downside to this is that each domU can talk directly to another domU without the dom0 seeing that (not sure if you could setup some filtering rules on the bridge or similar).

If you really needed to, create a separate bridge for each domU... only then you will waste 3 IP's for each domU (one network, one broadcast, one for dom0).

As far as vif-route, sorry, never tried it so can't help there.


Adam Goryachev Website Managers www.websitemanagers.com.au

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