[Engine-devel] Network Wiring

[Moti Asayag]

On 11/13/2012 07:58 PM, Simon Grinberg wrote:
> From the summary:
> "...It supports the following actions without unplugging the Vnic, and it maintains the device address of the Vnic ...."
> 
> But in the dialogue section:
> "If the Vnic is plugged there should be a message on top of the dialog "Please notice, changing Type or MAC will cause unplugging and plugging the Vnic" 
> 
> Looking at the detailed design indeed any change indeed goes through plug/unplug.
> Please correct me if I got the above wrong. 

Changing the network (rewiring network) is done using new API with VDSM,
updateVmInteface.

Therefore plug/unplug won't be executed for any of:
1. Changing the network to other network or disconnecting/unwiring it).
2. Update the name of the VM (db only).

Other changes to VM properties (i.e. MAC address, driver type) will
require the plug/unplug. Same goes to any explicit 'unplug' command.

> 
> To support real live rewire == "Move a card from one network to another" 
> The sequence should be for wired-plugged card: 
> - Unwire
> - Change network 
> - Rewire 
> 
> I would argue that we should actually force the user to perform these steps, but we can do it in one go.

The intention is to use the new API VDSM.libvirtVm.updateVmInteface for
performing the network rewire in a single command.

> 
> Any other state may change network freely.
> 
> To change name - it's just DB, so any state goes 
> 
> To change type or MAC address (= property), must go through unplug regardless to the wired state 
> So:
> - Unplug 
> - Change property 
> - Plug 
> 
> Again should probably ask the user to do these 3 steps so he'll know what he is doing, but we can do it for him with proper warning.
> 
> I also wander I do we have to drop the PCI address in the persisted table in this case - loosing the PCI location is redundant and will cause a move to another eth0 number in the guest. On the other hand changing of MAC may break network scripts anyhow - so I don't have a strong argument to keep it. 
> 
> 
> Another issue:
> If the nic is there to be use by a hook, then you probably want to allow 'none' network.
> This may also be useful when allowing to purge a network while it is connected to VMs: unwire on all nics and connect to the none network.
> 
> 
> Overall, looking great, and I like the wired vs unplugged that emulate real behavior. 
> 
> Regards, 
> Simon
> 
> 
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> 
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> 
> ----- Original Message -----
>> From: "Alona Kaplan" <alkaplan at redhat.com>
>> To: engine-devel at ovirt.org, "Simon Grinberg" <sgrinber at redhat.com>, rhevm-qe-network at redhat.com
>> Sent: Tuesday, November 13, 2012 4:46:52 PM
>> Subject: Network Wiring
>>
>> Hi all,
>>
>> Please review the wiki and add your comments.
>>
>> http://wiki.ovirt.org/wiki/Feature/NetworkWiring
>>
>>
>> Thanks,
>> Alona.
>>
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