Re: [Engine-devel] live migration and different technologies

On 06/08/2012 06:54 PM, Daniel P. Berrange wrote: >On Wed, Jun 06, 2012 at 05:15:53PM +0300, Itamar Heim wrote: >>Hi Daniel, >> >>on the quantum-ovirt call today the question of live migration >>between multiple technologies was raised. >> >>iirc, you implemented the abstraction in libvirt between what the >>guest sees and the actual host networking implementation for live >>migration. >> >>can you please share if there are any considerations around live >>migrations across different network implementations (bridge, sr-iov, >>ovs, qbg, openflow, etc.) > >Yes, we added the ability to use libvirt's 'virtual network' APIs >(virNetworkXXXXX) to define host networks using bridging, macvtap, >etc, etc. A guest's NICs can then be configured solely using ><interface type='network'>. This means that the guest XML will >not have any host-specific data in it, as you see when using ><interface type='bridge'> or<interface type='direct'> > >This means you can migrate between machines where the bridges have >different names (eg br0 on host A and br7 on host B), without any >limitations. > >You can also migrate between different impls of the same technology >(eg traditional software bridging vs macvtap bridging without >limitations. > >Finally, you can migrate between completely different technologies >(eg bridging vs vepa), but you will likely loose connectivity in >the guests, since the technologies are not compatible at the ethernet >layer. can you please explain this point - how would packet going out of the host or arriving to the guest would be different between a bridged and a vepa implemtnaiton?