[Libguestfs] [PATCH] v2v: remove MAC address related information

[Michal Skrivanek]

> On 27 Feb 2018, at 17:41, Richard W.M. Jones <rjones at redhat.com> wrote:
> 
> On Tue, Feb 27, 2018 at 04:43:15PM +0100, Michal Skrivanek wrote:
>>> We're passing the source MAC through into the OVF (see rasd:MACAddress
>>> and v2v/create_ovf.ml).  Does oVirt use it?
>> 
>> no. Exactly for the reason Tomas mentioned, the MAC spaces are
>> almost always entirely different and we reallocate a different MAC
>> every time
> 
> That's oVirt's decision, and we can work around it as described by
> erasing MAC addresses when the target is oVirt.  The patch will need
> to be more complete because it must at the very least deal with
> NetworkManager & Windows.
> 
> However ... I'm pretty sure this is going to cause problems for oVirt.
> It will mean in some circumstances that ethernet ports are swapped
> (which can be serious - you don't want your public and private LANs to
> get swapped over, although usually the result will be failure rather
> than the guest sending out private information over a public port).
> 
> Also you'll have problems which anything which keys off the MAC
> address to derive system-unique numbers, like license servers.

The reason for all that is that oVirt has a concept of MacPool which is a set of MAC addresses (range) allowed in a particular DC. That’s typically different than VMware’s even though it could be configured to overlap. The constraints are coming from that - when the VM is added it cannot conflict with any VM already there (that can happen even for overlapping ranges) and such VM is invalid (we strive not to create it as such under no circumstances)

A clean way would be to use “add NIC” API which does the MAC allocation. In fact that’s what’s happening when we import a VM with NICs with no MACs internally. Maybe a better long-term solution would be to use the API in a similar way as upload API - to define/reserve NICs. That way virt-v2v does have the information which NIC it is and maybe it can map them correctly. Would it make sense to explore?

Thanks,
michal

> 
> Rich.
> 
> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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