[libvirt] Network Configuration question

Remko Nolten remko at nolten.nu
Tue Feb 17 00:17:19 UTC 2009


On 09 Feb 2009, at 17:00, Paul de Weerd wrote:

> On Mon, Feb 09, 2009 at 04:51:34PM +0100, Remko Nolten wrote:
>> Thanks for your response. I'm afraid this will not work since the ip-
>> addresses for the VM's have a /32 netmask and no default gateway  
>> which
>> is required when you create a interface using a bridge.
>>
>> This how it works in a (non-virtualized) system at our hosting
>> organization:
>> For example, my server has one main ip-address, 10.255.255.0 on eth0,
>> and our hosting organization gives us 3 extra ip-addresses (so our  
>> range
>> is 10.255.255.0/30) which are routed to 10.255.255.0. On our  
>> server, we
>> can add the ip-addresses using:
>>
>> 	ip addr add 10.255.255.1/32 dev lo
>> 	ip addr add 10.255.255.2/32 dev lo
>> 	ip addr add 10.255.255.3/32 dev lo
>
> This is not quite correct. The physical interface (eg. eth0 in the
> case of linux) has an IP address in a different network (say, for
> example, 192.168.0.1/24). The /32's are routed to this address. Since
> the machine has a default route (eg. to 192.168.0.254), this works
> fine.
>
> Cheers,
>
> Paul 'WEiRD' de Weerd
>
>> So, our server gets the routed packages and will recognize them as  
>> one
>> of his own which enables us to add listeners to the ip-addresses like
>> Apache or a mail-server.
>>
>> In our case, we don't want the server to route the packages to the
>> loopback interface (so that services can listen to it), but we want  
>> the
>> server to route the traffic to the virtual machine. The more I  
>> think of
>> it, I suspect we need the "route" network option like this:
>>
>> <network>
>> 	<name>local</name>
>> 	<bridge name="virbr%d" />
>> 	<forward mode="route" dev="eth0"/>
>> 		<!-- dev is the device which is directly connected to the network  
>> and
>> has ip 10.255.255.0-->
>> 	<ip address="10.255.255.0" netmask="255.255.255.4">
>> 	  <dhcp>
>> 	    <range start="10.255.255.1" end="10.255.255.3" />
>> 	  </dhcp>
>> 	</ip>
>> </network>
>>
>> Is this correct?
>>

I got a short response from our hosting association. With this, I will  
bump this discussion one last time with the hope that somebody can  
give us a definitive answer for this problem.

Best regards,

-- 
Remko Nolten
Tel: 		06-45600767
E-mail: 	remko at nolten.nu






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