On Thu, Oct 30, 2014 at 08:37:14AM -0700, Ben Pfaff wrote:
> On Thu, Oct 30, 2014 at 03:55:45PM +0530, Shashwat Srivastava wrote:
> > I was going through openflow specs 1.4 and as mentioned in section
> > 7.3.4.1. page no. 73 "If the flag OFPTMPEF_IMPORTANCE is the only flag
> > set, eviction will
> > be performed strictly in order of importance, that is flow entry with
> > lower importance will always be evicted before flow entry with higher
> > importance.", I have some queries regarding eviction behaviour.
> >
> > Considering the case when Eviction is enabled on the basis of IMPORTANCE
> > (i.e. flows of lower importance will be evicted) and the table limit is
> > set to 5. Now suppose there are 5 flows of importance 100,101,102,103,104.
> > Now when the new flow is entered and has IMPORTANCE=10 and as the eviction
> > is enabled, the switch will evict flow having IMPORTANCE=100.
> > Now is'nt this illogical to evict flow of higher importance (in this case
> > importance=100) for the new flow of lower importance (in this case
> > importance=10).
> >
> > Considering the users above importance=50 as PLATINUM user and user with
> > importance < 50 as normal user. So for a normal user a platinum user's
> > service will be disrupted and will suffer loss of packet (although for
> > short period of time).
>
> That is a good question. I filed EXT-502, "Eviction when new flow is
> less important than any existing flow," to pose this question for
> clarification with the ONF extensibility working group.
Jean Tourrilhes provided a quick opinion:
If you assume "importance only", I would vote no. Trying to
squeeze a low importance flow entry by displacing more important
flow entry does not make sense. IMHO, the text is ambiguous and
could be interpreted both ways. The prototype for EXT-192 refuses
inserting the flow entry in that case and returns
OFPFMFC_TABLE_FULL. By the way, you may want to point the
developer to the prototype, that could help him...
I believe that the prototype that Jean refers to is:
https://github.com/jean2/ofsoftswitch13/commits/linda/ext-192-eviction
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