[libvirt] [PATCHv2] Configure native vlan modes on Open vSwitch ports

[Laine Stump]

(I'm not sure what you did differently when you sent this mail, but
somehow your mailer botched the "In-Reply-To:" header, which broke the
threaded display in Thunderbird. No big deal, but I thought you might
want to know.)

On 04/22/2013 12:51 PM, james robson wrote:
>> Date: Thu, 18 Apr 2013 14:14:32 -0400
>> From: Laine Stump <laine at laine.org>
>> To: libvir-list at redhat.com
>> Subject: Re: [libvirt] [PATCHv2] Configure native vlan modes on Open
>> 	vSwitch ports
>> Message-ID: <51703808.2000504 at laine.org>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> On 04/18/2013 01:44 PM, james robson wrote:
>>> Hello,
>>> Has any one been able to review this yet? I realise that the 'Since
>>> 1.0.3' in the doc page is now out of date, but is the code itself
>>> acceptable?
>> I was hoping that someone with more knowledge of Open vSwitch and/or
>> vlan tagging/trunking/native mode would repond to the message (Kyle?)
>> but there was silence instead...
>>
>>
>>>
>>> diff --git a/tests/networkxml2xmlin/openvswitch-net.xml
>>> b/tests/networkxml2xmlin/openvswitch-net.xml
>>> index a3d82b1..93c49d5 100644
>>> --- a/tests/networkxml2xmlin/openvswitch-net.xml
>>> +++ b/tests/networkxml2xmlin/openvswitch-net.xml
>>> @@ -21,4 +21,13 @@
>>>        <parameters profileid='alice-profile'/>
>>>      </virtualport>
>>>    </portgroup>
>>> +  <portgroup name='tagged'>
>>> +    <vlan native_mode='tagged' native_tag='123'>
>>> +      <tag id='555'/>
>>> +      <tag id='444'/>
>>> +    </vlan>
>>> +    <virtualport>
>>> +      <parameters profileid='tagged-profile'/>
>>> +    </virtualport>
>>> +  </portgroup>
>> As brought up again in a separate conversation today, we prefer to use
>> camelCase rather than underscored in attribute and element names. So, if
>> we were to use the layout you're proposing, the attributes should be
>> called "nativeMode" and "nativeTag".
>>
>> However, I'm wondering if there might be a better way to structure it.
>> What about this?
>>
>>
>>    <vlan trunk='yes'>
>>      <tag id='123' native='tagged|untagged'/> (or whatever values are
>> appropriate)


Sounds like this can be "native='yes'", since there is only the
possiblity of a tag being the native tag, or *not* being the native tag.


>>      <tag id='555'/>
>>      <tag id='444'/>
>>    </vlan>
>>
>> Do I understand correctly that native mode is telling what to do with
>> packets that come in untagged, and that (using your nomenclature
>> "native_mode='yes' native_tag='123'" means "when an untagged packet come
>> in from this interface, it should be tagged as 123 before forwarding"?
> That is correct, setting the native vlan changes how an untagged packet
> is handled when it enters the port. The difference between the 'tagged'
> and 'untagged' modes is in how packets on the native vlan are processed
> before exiting the port.
>
>
>> And what happens when native_mode='yes' but there is no native_tag?
> In that case you configuration is invalid, and will get an error. 


Okay, then doing the config the way I suggest would eliminate that
possibility, so it has an upside :-)


>
>
>> (that's what I was trying to describe with <tag id='123'
>> native='untagged'/>, but I don't even know if that makes sense, because
>> I don't know exactly what is the native vlan tag and what is done with
>> it :-)
> That arrangement would make sense, I chose the arrangement I did for two
> main reasons. There can only be one native vlan on a port, making it an
> attribute of the 'vlan' tag enforces this. Also, I wanted to keep the
> validation and processing separate rather than add 'if native' branches
> to the loops that operate on the vlan id list.
> I can see the advantage of having a single setting to configure the
> native vlan, rather than the two attributes I proposed. If the new
> suggestion is preferred I can rework my patch to use that format.

I think it's simpler, to do it that way, yes.


>
>
>> Also, is it valid to have a native_mode/native_tag if trunk='no'? (right
>> now trunk is automatically set to 'yes' if there is more than one vlan tag)
> It isn't valid to have trunk='no' and the native settings. Therefore
> "<vlan trunk='no' native_mode='tagged' native_tag='123'>" will get an
> error if you try to enter it. 
> If no "trunk" attribute is set explicitly then it will be set to 'yes'.
> This means "<vlan native_mode='tagged' native_tag='123'>" is equivalent
> to "<vlan trunk='yes' native_mode='tagged' native_tag='123'>".

Likewise, if you have more than one <id tag='x'/> element, trunk will
automatically be set to yes.

So in the end, if you don't foresee any problems with it, I think I do
prefer this:

   <vlan trunk='yes'>
     <tag id='123' native='yes|no'/> (default is 'no', only one allowed to be yes)
     <tag id='555'/>
     <tag id='444'/>
   </vlan>


Note that we'll be going into freeze for 1.0.5 soon, so if you are able
to rework the patch within the next couple days, it should go into
libvirt-1.0.5 (which *might* end up in Fedora 19?)