simple_switch_13.py: Added ability to use buffer_id in FlowMod

This avoids to send two packets (FlowMod & PacketOut).

OF v1.3.1 (the specification most switch vendors implemented) mentions
in A.3.4.1 on page 65 that this is a valid way to avoid two packets.

Signed-off-by: Benny Eggerstedt <benjamin.eggerstedt@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 15 insertions, 6 deletions

diff --git a/ryu/app/simple_switch_13.py b/ryu/app/simple_switch_13.py
index 0e1574fd..b9cbad0f 100644
--- a/ryu/app/simple_switch_13.py
+++ b/ryu/app/simple_switch_13.py
@@ -47,15 +47,19 @@ class SimpleSwitch13(app_manager.RyuApp):
                                           ofproto.OFPCML_NO_BUFFER)]
         self.add_flow(datapath, 0, match, actions)
 
-    def add_flow(self, datapath, priority, match, actions):
+    def add_flow(self, datapath, priority, match, actions, buffer_id=None):
         ofproto = datapath.ofproto
         parser = datapath.ofproto_parser
 
         inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
                                              actions)]
-
-        mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
-                                match=match, instructions=inst)
+        if buffer_id:
+            mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id,
+                                    priority=priority, match=match,
+                                    instructions=inst)
+        else:
+            mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
+                                    match=match, instructions=inst)
         datapath.send_msg(mod)
 
     @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
@@ -95,8 +99,13 @@ class SimpleSwitch13(app_manager.RyuApp):
         # install a flow to avoid packet_in next time
         if out_port != ofproto.OFPP_FLOOD:
             match = parser.OFPMatch(in_port=in_port, eth_dst=dst)
-            self.add_flow(datapath, 1, match, actions)
-
+            # verify if we have a valid buffer_id, if yes avoid to send both
+            # flow_mod & packet_out
+            if msg.buffer_id != ofproto.OFP_NO_BUFFER:
+                self.add_flow(datapath, 1, match, actions, msg.buffer_id)
+                return
+            else:
+                self.add_flow(datapath, 1, match, actions)
         data = None
         if msg.buffer_id == ofproto.OFP_NO_BUFFER:
             data = msg.data