[Users] Networking problem inside a openvz virtual machine

Michael Schwartzkopff misch at multinet.de
Thu Jun 12 06:15:24 EDT 2008


I want to setup a Linux-HA cluster inside a vitual openvz machine. Due to the 
nature of openvz virtual machines I have a problem with IP address resources.

Let me explain the problem: Inside openvz virtual machine there are two 
different network devices venet and veth.

As far as I understood the documentation, using venet devices you cannot 
change the ip address inside the virtual machine. So no chance to set up a 
cluster using IPaddr2 resource the easy way. So no chance to let heartbeat 
control the IP adress here.I have a ugly workaround, but  that is not the 
topic here.

Using veth device you can change the IP address inside the virtual machine. 
But  you have to set up proxy arp on the host machine and also the host has 
to know about routing to that machine. If the IP address resource inside the 
virtual machine is moved away to an other virtual machine located on the same 
host or another one, the original host will still advertise its MAC address 
for the vitual IP adress of the cluster and will route the packets to the 
virtual machine not serving the IP address any more.

Did I understand OpenVZ documentation right?
Is there any way out of this dilemma using heartbeat inside openvz vitual 


Dr. Michael Schwartzkopff
MultiNET Services GmbH
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