[ovs-dev] [PATCH 4/7] Keep all of tunnel metadata in flow.

[Jesse Gross]

On Mon, Apr 29, 2013 at 10:21 PM, Rajahalme, Jarno (NSN - FI/Espoo)
<jarno.rajahalme at nsn.com> wrote:
>
> On Apr 29, 2013, at 20:49 , ext Jesse Gross wrote:
>
>> On Sun, Apr 28, 2013 at 11:29 AM, Rajahalme, Jarno (NSN - FI/Espoo)
>> <jarno.rajahalme at nsn.com> wrote:
>>>
>>> Another thing that I came to think only when reading Ben's new tutorial:
>>> Output to the input port is skipped. This would be a problem if you only
>>> have one generic flow based GRE port (as enabled by the last patch in
>>> this series), and you should forward GRE input to another GRE output.
>>> This could be fixed by always allowing output (in xlate_output_action())
>>> to a tunnel that has cfg.ip_dst_flow set, even if the output port is the
>>> same as the input port. Thoughts?
>>
>> I know that Ben was thinking about ways to relax this check anyways,
>> so it might be good to see how that fits with this.
>
>
> It seems to me that it should be relatively safe to allow packets that have
> been modified by actions to be sent to the input port, if so directed by the
> flow action. At least when the destination mac has been changed.

The concern that Ben had was that this changes OpenFlow semantics and
that will lead to confusion over time. You coud make a similar
argument about vlans: performing a vlan action should disable the
loopback check. However, that is not what the spec says.