[ovs-dev] I think I found a bug

[Justin Pettit]

In my opinion, we should remove that requirement from OpenFlow that exact match rules always have the highest priority.  It sounds like it's already been removed in OpenFlow 1.1.  Unfortunately, we're kind of stuck in OpenFlow 1.0, since I know controllers are written to expect that behavior.

--Justin


On Feb 21, 2011, at 11:33 PM, Derek Cormier wrote:

> Thanks, I'll give that a read.
> 
> What do you think about identical flows with no wildcards but different priorities? I notice that open vswitch just sets the priority to 65535 for exact flows. Should identical flows with different priorities also be allowed?
> 
> - Derek
> 
> On 02/22/2011 04:20 PM, Justin Pettit wrote:
>> Yes, I was using some poetic license in saying that we lost; that flag was put in there as a sort of compromise for those of us not in favor of always enforcing that behavior.  If you're really interested, you can see some of the discussion starting here:
>> 
>> 	https://mailman.stanford.edu/pipermail/openflow-dev/2008-April/000133.html
>> 
>> --Justin
>> 
>> 
>> On Feb 21, 2011, at 11:03 PM, Romain Lenglet wrote:
>> 
>>> Hi,
>>> I thought that accepting (or not) overlapping flows at the same priority was up to the controller?
>>> Isn't that what the check_overlap flag is for in flow_mod messages?
>>> -- 
>>> Romain Lenglet
>>> 
>>> On Tuesday, February 22, 2011 at 16:00, Justin Pettit wrote:
>>> 
>>>> I would expect so. One use that people have brought in the past is that you could setup backup routes at a lower priority, with the higher ones timing out or being forcibly removed. I don't know how useful that actually is, but people have discussed doingg that before with OpenFlow.
>>>> 
>>>> In general, Ben and I have been fairly negative in the OpenFlow discussions about putting in "sanity" checks at flow insertion time due to the complexity and expense of enforcing them. There was quite a lengthy discussion a year or so back about preventing users from being able to put overlapping flows at the same priority--we lost that one. :-)
>>>> 
>>>> --Justin
>>>> 
>>>> 
>>>> On Feb 21, 2011, at 10:52 PM, Derek Cormier wrote:
>>>> 
>>>>> I expected that since the flow with the lower priority will never be matched over the higher one, it has no purpose and would not be added.
>>>>> 
>>>>> Hmm, on second glance, the protocol says that if you add an identical flow that also has the same priority then the flow will just be replaced.
>>>>> But, I don't think it says anything about this case. Sorry, I should have confirmed that before posting.
>>>>> 
>>>>> That said, do you think these identical flows should be allowed?
>>>>> 
>>>>> - Derek
>>>>> 
>>>>> On 02/22/2011 03:43 PM, Justin Pettit wrote:
>>>>>> I would expect that you can. What did you expect? What did you see? It's not clear from this output if it's working or not, since neither couunter shows a value. Are you running traffic?
>>>>>> 
>>>>>> --Justin
>>>>>> 
>>>>>> 
>>>>>> On Feb 21, 2011, at 10:35 PM, Derek Cormier wrote:
>>>>>> 
>>>>>>> Should I be able to add two identical wildcarded flows with different priorities? I was talking with KK and he thinks this might be a bug. I always assumed this was just the way it works. Here is my ovs-ofctl flow dump:
>>>>>>> 
>>>>>>> cookie=0x0, duration=94.608s, table_id=0, n_packets=0, n_bytes=0, priority=5,dl_type=0x0005 actions=drop
>>>>>>> cookie=0x0, duration=98.109s, table_id=0, n_packets=0, n_bytes=0, priority=1,dl_type=0x0005 actions=drop
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> - Derek
>>>>>>> 
>>>>>>> _______________________________________________
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>>>>>>> http://openvswitch.org/mailman/listinfo/dev_openvswitch.org
>>>> 
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>> 
>> 
>