[ovs-dev] [PATCH] OPENFLOW-1.1+: note on table-miss

YAMAMOTO Takashi yamamoto at valinux.co.jp
Tue Oct 15 01:20:04 UTC 2013


> On Wed, Oct 09, 2013 at 04:49:06PM +0900, YAMAMOTO Takashi wrote:
>> Signed-off-by: YAMAMOTO Takashi <yamamoto at valinux.co.jp>
> 
> ...
> 
>> +      This requires the following.
>> +      - Change the default table-miss action (in the absense of table-miss
>> +        entry) from packet_in to drop for OF1.3+.  Decide what to do if
>> +        a switch is configured to support multiple OF versions.
>> +      - Distinguish table-miss flow entry and make its packet_in reason
>> +        OFPR_NO_MATCH.  (OFPR_TABLE_MISS for OF1.4)
>> +      - Avoid a table-miss flow entry matching to packets if there are
>> +        ordinary flow entries with priority 0 in the table.  I.e. The
>> +        table-miss flow entry should have lesser effective priority.
> 
> I wasn't aware that the table-miss flow entry was supposed to have lower
> effective priority than other flow entries with table 0.  Does the text
> of the standard say this or imply this somewhere?

the standard is obscure as usual.  surely there is a room
for different interpretations.

OF 1.3.2 2 Switch Components (p.8)
>   If a matching entry is found, the instructions associated with the
>   specific flow entry are executed. If no match is found in a flow
>   table, the outcome depends on configuration of the table-miss flow
>   entry:
this seems to support lower effective priority behaviour.

OF 1.3.2 5.3 Matching (p.15)
the figure seems to imply the same.

OF 1.3.2 5.4 Table-miss (p.16)
>   The table-miss flow entry matches packets in the table as expected
>   from its set of match fields and priority
this sentence seems to say the opposite.

is there anything else to look at then the standard pdf?
(ONF-private stuff like openflow.h?)

YAMAMOTO Takashi




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