Oops, I meant n_tables = 255, table_id = 254. So we will report that table_id=254 isn't usable for controllers with OF1.1+. Thank you for clarification.
thanks, On Thu, Aug 16, 2012 at 09:18:31AM -0700, Ben Pfaff wrote: > On Thu, Aug 16, 2012 at 05:16:53PM +0900, Isaku Yamahata wrote: > > Hi. Right now OVS tells a controller that 256 tables available > > as SWITCH_FEATURES response. > > (i.e. ofp_switch_features->n_tables = 256 = N_TABLES) > > It should say 255, are you sure about 256? > > > But the table whose id is TBL_INTERNAL = N_TABLES - 1 is used for ovs > > internal use so can't be available to a controller. > > The controller can't modify it, but it is allowed to view it. > > > Addition to the above, the document, DESIGN, says that > > > Tables 128 and above are reserved for use by the switch itself. > > > Controllers should use only tables 0 through 127. > > > > So what should be returned as n_tables? > > - 256 (current value) > > With OF1.0, there is no way to know that table id 255 is unusable. > > OF1.0 uses table id 255 as a special value in many places, but what > you write is true of table 254. > > I don't think that it is meaningful to say that table 254 is not > usable in OF1.0, because in OF1.0 there is no way to place a flow in a > particular table. Open vSwitch will always place flows in table 0, if > the controller uses OF1.0 without extensions. So, I can't see how the > controller can be bothered by such a reserved table. > > > With OF1.1+, allowed operations can be described. So a controller can know > > that which tables are actually usable. > > I hadn't noticed that but it is a useful fact. > > > - 255 > > This reflects the reality, but contradicts to the document, DESIGN. > > DESIGN says: > > The Open vSwitch software switch implementation offers 255 flow > tables. > > > - 128 > > Actually 255 tables are usable. > > I don't see how there is a practical problem here. > -- yamahata _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
