On Sat, Jun 09, 2012 at 03:57:40PM +0300, Itamar Heim wrote: > 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?
I'm not the expert on VEPA - I'm just relaying what I have been told wrt VEPA modes in the past. IIUC, with VEPA modes there is quite alot of extra traffic due to a handshake negotiation between the host & switch, before any guest traffic can pass, and there needs to be a special synchronization done with VEPA during migration to maintain state in the switch. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ Engine-devel mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/engine-devel
