[ovs-dev] [eviction 12/12] Add support for limiting the number of flows in an OpenFlow flow table.

[Ben Pfaff]

On Tue, Jan 31, 2012 at 06:00:33PM -0800, Ethan Jackson wrote:
> I'm surprised that the Flow_Table configuration went into the database
> instead of being implemented as OpenFlow extensions. Naively, to me it
> seems like a bit of a layering violation.  Can you please briefly
> explain your thinking on this issue?

My thoughts on the division between the two protocols is:

        - Anything that doesn't apply to a particular OpenFlow switch
          but to the system as a whole goes in the DB.  (Doesn't apply
          here.)

        - Anything that changes potentially very quickly goes in the
          OpenFlow protocol.  Generally speaking, that is per-flow
          state.  (Doesn't apply here.)

        - Anything specific to a particular OpenFlow connection has to
          go in OpenFlow, obviously.  (Doesn't apply here.)

        - Otherwise, it usually goes in the config protocol.

I'm going to discuss the choice of protocols with Justin, to see what
he thinks, before I push this.

> In ofproto_configure_table() I would think the initial assertion
> should come before we dereference ofproto->tables.  Practically
> speaking, it doesn't matter much, just looks a tad strange to me.

Good idea.  I made that change.

Thank you for the reviews!