[ovs-discuss] Flow removed message bug

kk yap yapkke at stanford.edu
Tue Feb 22 02:04:33 UTC 2011


Hi Derek,

Actually priority for exact match does not matter.  So, there cannot
be two different exact match flow entries that only differ by
priority up till at least OpenFlow 1.0.  That's the case I was thinking about.

Regards
KK

On 21 February 2011 17:54, Derek Cormier <derek.cormier at lab.ntt.co.jp> wrote:
> Hi KK,
>
> Thanks for posting this to the openflow-spec board. I do think the priority
> should be maintained since two identical flow matches can exist with
> different priorities. If one of them is removed, it could be useful to know
> which one. To identify a flow uniquely, I believe you need the ofp_match &
> priority (unless a cookie is used).
>
> - Derek
>
> On 02/22/2011 03:27 AM, kk yap wrote:
>>
>> Hi,
>>
>> I believe maintaining the wildcards would be enough.  To me, the
>> following two matches are the same:
>>
>> Wildcards = ALL - DL_TYPE, DL_TYPE = 5, IP_SRC = 100...
>> Wildcards = ALL - DL_TYPE, DL_TYPE = 5, IP_SRC = 0...
>>
>> I believe Ben and Justin is saying that it is reasonable to maintain
>> the wildcard field.  Seems like we have a working solution?
>>
>> I will post this on the openflow-spec list for the words to be cleared
>> up.  The priority field worries me a little more, such I think exact
>> match is normalized to priority 65535?  Should that be maintained in
>> flow_removed?  I wonder.
>>
>> Regards
>> KK
>>
>> On 21 February 2011 09:30, Ben Pfaff<blp at nicira.com>  wrote:
>>>
>>> On Sun, Feb 20, 2011 at 11:36 PM, Derek Cormier
>>> <derek.cormier at lab.ntt.co.jp>  wrote:
>>>>
>>>> I see what you mean and I agree that a switch shouldn't store
>>>> unnecessary
>>>> information. But is it really a burden in this case? The wildcards are
>>>> stored in a single 32-bit integer, so no extra space is needed.
>>>
>>> The data structure that OVS uses for classification requires that
>>> wildcarded fields
>>> be zeroed for efficiency reasons.  In other words, storing the wildcards
>>> isn't a
>>> big deal, but storing nonzero values of wildcarded fields would require
>>> extra
>>> memory.  So I'd rather not do it, although certainly it's not a huge
>>> deal if in the
>>> OVS has to.
>>>
>>> _______________________________________________
>>> discuss mailing list
>>> discuss at openvswitch.org
>>> http://openvswitch.org/mailman/listinfo/discuss_openvswitch.org
>>>
>>
>
>




More information about the discuss mailing list