The following is a list of the currently known limitations of the network filtering subsystem.
- VM migration is only supported if the whole filter tree that is referenced by a guest virtual machine's top level filter is also available on the target host physical machine. The network filter
clean-trafficfor example should be available on all libvirt installations and thus enable migration of guest virtual machines that reference this filter. To assure version compatibility is not a problem make sure you are using the most current version of libvirt by updating the package regularly.
- Migration must occur between libvirt installations of version 0.8.1 or later in order not to lose the network traffic filters associated with an interface.
- VLAN (802.1Q) packets, if sent by a guest virtual machine, cannot be filtered with rules for protocol IDs arp, rarp, ipv4 and ipv6. They can only be filtered with protocol IDs, MAC and VLAN. Therefore, the example filter clean-traffic Example 18.1, “An example of network filtering” will not work as expected.