[ovs-dev] flows in Flow Table?

[Ben Pfaff]

The tables have different purposes.  A flow in the classifier is an
OpenFlow flow that may contain wildcards.  A flow in the datapath
(e.g. dp_netdev) is always exact-match (to allow hashing).

On Thu, Sep 08, 2011 at 07:13:24PM +0500, Bibrak Qamar wrote:
> But when dpif-netdev is used does it store flows in both of the tables? I
> mean why are we maintaining two tables?
> 
> 
> 
> struct classifier {
>     int n_rules;                /* Total number of rules. */
>     struct hmap tables;         */* Contains "struct cls_table"s.  */*
> };
> 
> struct dp_netdev {
> ..
> ..
>  struct hmap flow_table;   *  /* Flow table. */*
> ..
> }
> 
> When a new flow (packet) is received does it look_up in classifier's table
> or  netdev's flow_table for match?
> 
> Thanks for your help
> Bibrak
> 
> On Thu, Sep 8, 2011 at 7:04 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Thu, Sep 08, 2011 at 06:10:45PM +0500, Bibrak Qamar wrote:
> > > Ok now I have got some idea. In the classifier there is a data structure
> > > which stores the rules, i.e
> > >
> > > struct classifier {
> > >     int n_rules;                /* Total number of rules. */
> > >     struct hmap tables;         /* Contains "struct cls_table"s.  */
> > > };
> > >
> > > And in the netdev there is also a data structure which stores the flows,
> > i.e
> > >
> > >
> > >
> > > dp_netdev_lookup_flow
> >
> > That's the userspace implementation of the datapath.  If you're using
> > the Linux kernel module, nothing in dpif-netdev.c is used; the code in
> > dpif-linux.c is used instead.
> >