Re: [Engine-devel] Network Wiring

On 11/15/2012 02:29 PM, Dan Kenigsberg wrote: > On Wed, Nov 14, 2012 at 02:12:07PM -0500, Simon Grinberg wrote: >>> >>> The intention is to use the new API VDSM.libvirtVm.updateVmInteface >>> for >>> performing the network rewire in a single command. >> >> What does it do? I could not find updateVmInteface in vdsm git. >> Where is this defined? >> >> It's critical. >> >> - You can change the interface directly by moving the VM from one >> network to another >> - You can do that but toggle the ling state so the VM will be aware. >> >> Which if these two? >> If you do only the first then it's not the common use case. In most >> cases you must toggle the link status to the VM. >> This will cause: >> 1. Speed negotiation + arp request that also informs the switched >> about the change >> 2. In case it's DHCP (which most likely the case for guests) it will >> trigger new DHCP request. >> >> If you don't baaad things will happen :) > > I think that baaaaad things are going to happen anyway. In "baaaaad > things", I mean "stuff that require guest intervension". > > The guest may be moved from one subnet into another one, maybe on > different VLAN or physical LAN. We can not expect that the applications > running on it will be happy about these changes. A similar case appears > if we rewire the network while the VM is down (or hibernated). When the > VM is restarted, it is going to use mismatching IP addresses. > > You are right that it may make sense to request an new IP address after > the rewiring, however, a little test I just did on my desktop showed > that > dhclient does not initiate a new request just because the carrier > dropped for few seconds. So we should try harder if we want to refresh > dhcp after rewiring: I think that it would be cool to have a guest > agent verb > that does it.

shouldn't this simulate a link disconnect/connect event to the OS?

_______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel