Fix first ping package packet loss

example.py

@@ -200,8 +200,6 @@ class L3Switch(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=frame.dst)
-            self.logger.info(actions)
-            self.logger.info(match)
             # verify if we have a valid buffer_id, if yes avoid to send both
             # flow_mod & packet_out
             if buffer_id != ofproto.OFP_NO_BUFFER:
@@ -222,17 +220,26 @@ class L3Switch(app_manager.RyuApp):
         parser = datapath.ofproto_parser
 
         if ipv4_pkt.dst in self.ip_to_mac[dpid]:
+            # GEt mac and port of the given destination
             dstMac = self.ip_to_mac[dpid][ipv4_pkt.dst]
-        else:
-            self.send_arp(datapath, 1, self.MAC_ADDR, ipv4_pkt.src, "FF:FF:FF:FF:FF:FF", ipv4_pkt.dst, ofproto.OFPP_FLOOD)
-            return
-
             out_port = self.mac_to_port[dpid][dstMac]
+        else:
+            # Send an arp request and define mac and port
+            # so we're able to apply the following actions
+            # on the packet.
+            out_port = ofproto.OFPP_FLOOD
+            dstMac = "FF:FF:FF:FF:FF:FF"
+            self.send_arp(datapath, 1, self.MAC_ADDR, ipv4_pkt.src, dstMac, ipv4_pkt.dst, out_port)
+
+        # Actions are applied in the same order as defined in the list.
+        # OFPActionOutput terminates the chain. So this call should be the last action.
         actions = [parser.OFPActionDecNwTtl(), #decrease TTL count
             parser.OFPActionSetField(eth_src=self.MAC_ADDR), # set own mac as source
             parser.OFPActionSetField(eth_dst=dstMac), # set dst from arp request
             parser.OFPActionOutput(out_port)] # forward packet through out_port
 
+        # Only install a flow if we#re in the first case (specific mac and out_port)
+        if ipv4_pkt.dst in self.ip_to_mac[dpid]:
             # install a flow to avoid packet_in next time
             match = parser.OFPMatch(in_port=in_port, ipv4_dst=ipv4_pkt.dst, eth_type=0x0800) #onlz match ipv4 packets
 
@@ -243,6 +250,7 @@ class L3Switch(app_manager.RyuApp):
                 return
             else:
                 self.add_flow(datapath, 1, match, actions)
+
         data = None
         if buffer_id == ofproto.OFP_NO_BUFFER:
             data = packet.data
@@ -301,6 +309,7 @@ class L3Switch(app_manager.RyuApp):
                 if icmp_pkt:
                     self.do_icmp(datapath, in_port, eth, ipv4_pkt, icmp_pkt)
             else:
+                # forward the package into a different subnet
                 self.do_l3_switch(datapath, dpid, pkt, eth, ipv4_pkt, in_port, msg.buffer_id)