[libvirt-users] how to restart the network connection of kvm guest OS ?

Laine Stump laine at laine.org
Fri Mar 25 15:48:06 UTC 2011


On 03/25/2011 12:43 AM, Osier Yang wrote:
> ÓÚ 2011Äê03ÔÂ24ÈÕ 19:16, ºÎÎÄ´Ï Ð´µÀ:
>> When a vm move from one VLAN(e.g. VLAN 1) to another VLAN (e.g. VLAN 2),
>> it is needed to restart the network connection of guest OS, so that it
>> can begin a dhcp discover and get a new ip again. But i can't find the
>> way to restart the guest os's network connection by libvirt (neither
>> python API nor virsh command). Is any other ways?
>
> Hi,
>
> Won't virt-manager (if has) in your guest try to restart the network?
>
>> PS: i found that the VirtualBox can detach the cable of VMs and
>> re-attach so that the guest OS will recognize and restart a dhcp
>> discover when the cable re-attach. I guess the KVM will have some
>> feature like that , is anybody know something about that?
>
> Libvirt supports similar function.
> # virsh detach-interface
> # virsh attach-interface
>
> Or
> # virsh detach-device
> # virsh attach-device
>
> the difference between "*-device" and "*-interface" is the
> accepted arguments, the later one accepts interface xml.

Those present to the guest as if the interface itself was being 
unplugged. What he's looking for is a way to just emulate a loss of 
carrier on the interface (ie unplugging the *cable*). There is an open 
bug for that:

https://bugzilla.redhat.com/show_bug.cgi?id=643373

but no work has been done on it yet.

Note that the required qemu monitor command does exist: "set_link XXX 
off" and "set_link XXX on", but I was unable to get a form of "virsh 
qemu-monitor-command" that could make this work.




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