[P4-dev] What happens during table miss?

Archie anubhavnidhi1009 at gmail.com
Thu Jul 16 22:02:53 EDT 2015

Thanks for the reply. I have one more question. In openflow, the packet
specific rule, i.e. rules with values are installed in switches by the
controller. From the example given here
<https://github.com/p4lang/p4factory> under "Integration with Mininet" ,
the way actual entries are added to the table is using commands like the

python ../../cli/pd_cli.py -p simple_router -i p4_pd_rpc.simple_router -s
$PWD/of-tests/pd_thrift:$PWD/../../submodules/oft-infra -m "add_entry
send_frame 1 rewrite_mac 00:aa:bb:00:00:00" -c localhost:22222
Is this the only way to put table entries? Or are there other ways to fill
the table

Thanks again,

On Wed, Jul 15, 2015 at 7:32 PM, Antoine Kaufmann <
antoinek at cs.washington.edu> wrote:

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> Hi Archie,
> what happens with a P4 switch on a table miss is entirely controlled by
> the P4 program (plus runtime configuration). If the table has a default
> action that was added at runtime from the CPU, then that action will be
> executed. Regardless of whether there is a default action, you the
> control program can also branch on whether the lookup hit and missed.
> If you want the open flow behavior, you can implement this in P4, by
> either encapsulating and forwarding the packet to a remote controller,
> or locally forwarding it to the CPU.
> I hope that helps!
> Cheers,
> Antoine
> On Wed, Jul 15 18:41, Archie wrote:
> > Hi,
> >      I know in openflow, when a switch can't find a rule-match for a
> > packet, it forwards the packet to the controller. Does the same thing
> > happen in P4? Or is a table-miss handled in some other way in P4?
> >
> >
> > Thanks,
> > Archie
> --
> Antoine Kaufmann
> <antoinek at cs.washington.edu>
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