Re: [ 0/5] netdev ethernet allow to set ip, route and peer address

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On 04/07/2016 01:35 PM, Daniel P. Berrange wrote:
On Mon, Apr 04, 2016 at 09:00:01PM +0000, Vasiliy Tolstov wrote:
Some minor improvements and patch split as suggested by Laine Stump
FYI, make sure you include the word PATCH in mails, so they get
picked up by out patch tracking too, otherwise they could get
left without being noticed.


Regards,
Daniel

Something I've found myself worrying about lately while driving in the car or nodding off to sleep - are the "address" and "peer" attributes effectively used in the same way for all network connection types and both hypervisors? I think the answer may be "no", and if so we need to fix that before they go out in a release.

In particular, when an lxc domain's interface has:

   <ip address='192.168.128.1'/>

That is the IP address seen by the guest, not the host. So I would assume that if an LXC domain had:


   <ip address='192.168.128.1' peer='192.168.128.2'/>

that 192.168.128.1 would still be the IP address see by the guest, and 192.168.128.2 would be the IP address on the host side; and it should be the same for qemu.

From what I can see of the code, though, on a qemu domain, the IP address is set for the tap device's own IP, meaning that it would show up on the *host* side, while the peer address would be what the host expects to be at the other end of the tap device (i.e. the guest side), so the two attributes are used for the *opposite* end of the PTP link in lxc vs. qemu.

I think that, instead, the "address" attribute should *always* be the IP address that is seen/used by the guest, and the "peer" attribute should be the IP address that is seen/used by the host. (perhaps "peer" could be replaced with some other name, like "host" or "hostAddress" to avoid confusion? (don't like either of those alternatives, but I don't really like peer either)).

Aside from that, I can see that these patches have been pushed in the code that I'm running, and I've been trying to add "peer='blah'" to interface IP addresses on my test machine, but it's just removed from the config. Have you tested what got pushed? Has something gone wrong?

Since there hasn't been a release with these patches included yet, there is still time to fix it at least to be consistent (assuming that my suspicions are correct; I've been unable to test it myself for the reason above).

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