[pox-dev] h1 ping h3 from mininet via POX controller not working as expected.

[Karthik Sharma]

sorry I had added a -c1 at the end of the command.

 mininet> h1 ping h3



On 3 May 2013 17:16, Murphy McCauley <murphy.mccauley at gmail.com> wrote:

> Ping sends packets from A to B, and B sends them back to A.  Ping does
> this continually until you stop it unless you specify a limit on the
> commandline.
>
> Since you're installing flows, you'd actually expect them to start hitting
> the flow table and stop hitting the switch, but the fewest you could
> probably expect to see at the controller in that case is still three.
>
> -- Murphy
>
> On May 2, 2013, at 9:48 PM, Karthik Sharma wrote:
>
> I have mininet configured with a remote POX controller running.The
> configuration of mininet network is as shown below
>
>
>
>         h1 (eth0) ----------- s2(eth1)       s2(eth2) ---------- h3(eth0)
>
> where
>         h1: eth0 is  ca:bc:2e:0c:5a:52
>         h2: eth0 is  0a:79:40:89:44:cf
>
>
> The packet handling function in the POX network controller that gets
> called whenever a packet is forwarded to the controller is given below.The
> basic idea is that I use
> a database backed controller.If the packet destination address is not
> present in the database,I flood the packet.else I forward the packet to the
> appropriate port.
>
> def act_like_switch (self, packet, packet_in):
>     """
>     Implement switch-like behavior.
>     """
>     # Learn the port for the source MAC
>     print "RECIEVED FROM PORT ",packet_in.in_port , "SOURCE ",packet.src
> ,"DEST" , packet.dst
>     self.mac_to_port[packet.src]=packet_in.in_port
>     q_res =
> session.query(SourcetoPort).filter_by(src_address=str(packet.dst)).first()
>     if q_res is not None:
>            self.send_packet(packet_in.buffer_id,
> packet_in.data,q_res.port_no, packet_in.in_port)
>            #create a flow modification message
>            msg = of.ofp_flow_mod()
>            #set the fields to match from the incoming packet
>            msg.match = of.ofp_match.from_packet(packet)
>            #send the rule to the switch so that it does not query the
> controller again.
>            msg.actions.append(of.ofp_action_output(port=q_res.port_no))
>            #push the rule
>            self.connection.send(msg)
>     else:
>            #flood this packet out as we don't know about this node.
>            self.send_packet(packet_in.buffer_id,
> packet_in.data,of.OFPP_FLOOD, packet_in.in_port)
>            q_res =
> session.query(SourcetoPort).filter_by(src_address=str(packet.src)).first()
>            if q_res is None:
>                 entry = SourcetoPort(src_address=str(packet.src) ,
> port_no=packet_in.in_port)
>                 #add the record to the session object
>                 session.add(entry)
>                 #add the record to the session object
>                 session.commit()
>
>
> As mentioned above this function is running on a remote POX controller
> connected to the described mininet network.Now I do
>
> mininet> h1 ping h3
>
> The output that I get is as follows.I have put print statements in the
> beginning of act_like_switch() function.
>
> RECIEVED FROM PORT  1 SOURCE  ca:bc:2e:0c:5a:52 DEST 0a:79:40:89:44:cf
> RECIEVED FROM PORT  2 SOURCE  0a:79:40:89:44:cf DEST ca:bc:2e:0c:5a:52
> RECIEVED FROM PORT  1 SOURCE  ca:bc:2e:0c:5a:52 DEST 0a:79:40:89:44:cf
> RECIEVED FROM PORT  2 SOURCE  0a:79:40:89:44:cf DEST ca:bc:2e:0c:5a:52
>
> It seems that there are two ICMP messages from h1 to h2 and two ICMP
> messages from h2 to h1.
> I would expect only 1 ICMP message from host h1 to h2.Why are there so
> many messages.I did think of
> broadcast but why is the destination address not ff:ff:ff:ff:ff:ff ? The
> source and destination addresses seems to be swapped?
>
> Can anyone explain why this is happening? I am fairly new to POX and
> mininet
>
> Regards,
> Karthik
>
>
>
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