In the spec, ofp_flow_mod doesn't have a data parameter. POX has a special
case to support a common pattern, and your code isn't it.
You should just do a flow_mod followed by a packet_out (possibly to the
OFPP_TABLE special port).
-- Murphy
On Jul 26, 2013, at 9:00 AM, Keqiang He wrote:
> I refined the last message so that it is more clear:
>
> Hello --
>
> I want to install and modify flow entries from the controller. First, I
> proactively install new rules into the flow table in this way:
>
> #flow generate-- simulated flows
> for i in "a set of ip addresses":
> u = udp()
> u.srcport = 1
> u.dstport = 2
> p = ipv4()
> p.set_payload(u)
> p.srcip =IPAddr(i)#i is increased ip address such as 192.168.0.1,
> 192.168.0.2, 192.168.0.3, ... 192.168.1.255 ...
> p.dstip = IPAddr("192.168.56.100")
> e =ethernet (...)
> e.set_payload(p)
> #get a match from packet and tries to install a new rule...
> msg = of.ofp_flow_mod()
> msg.match = of.ofp_match.from_packet(packet)
> msg.idle_timeout = 0
> msg.hard_timeout = 0
> msg.actions.append(of.ofp_action_output(port = 1))
> self.connection.send(msg)
> Till now, the results is what I expected-- a set of new rules are installed
> in the flow table;
>
> Next, I want to modify the installed (newly installed rules). At the same
> time, I want to send out a packet which matches a particular rules so that I
> know that modified rule takes effect.
>
> The code is like this--
> #repeat the "flow generate-- simulated flows" procedure
> ...
> #
> #get a match from packet and tries to modify that rule...
>
> msg = of.ofp_flow_mod()
> msg.command = of.OFPFC_MODIFY (make sure that this command is for
> modification)
> msg.match = of.ofp_match.from_packet(packet)
> msg.idle_timeout = 0
> msg.hard_timeout = 0
> msg.data = e.pack()
> msg.actions.append(of.ofp_action_output(port = 2)) # the output port is
> modified here...
> self.connection.send(msg)
> Now, I get the error:
> ********error message*****************
> File "/home/sdn/pox/pox/openflow/
> of_01.py", line 687, in send
> data = data.pack()
> File "/home/sdn/pox/pox/openflow/libopenflow_01.py", line 2191, in pack
> self.buffer_id = self.data.buffer_id
> AttributeError: 'str' object has no attribute 'buffer_id'
> *********error message end**********
>
> I tested that If I change msg = of.ofp_flow_mod() to msg =
> of.ofp_packet_out(), it is fine. But I do not just want to send packet out.
> What I want to do is, first modify a rule and then send out a packet matching
> that rule.
>
>
> Can anyone help on the error? Thanks:)
>
> -------------end of the message---------------------
>
>
>
> On Fri, Jul 26, 2013 at 11:55 AM, Keqiang He <[email protected]> wrote:
> Hello --
>
> I want to install and modify flow entries from the controller. First, I
> proactively install new rules into the flow table in this way:
>
> #flow generate-- simulated flows
> for i in "a set of ip addresses":
> u = udp()
> u.srcport = 1
> u.dstport = 2
> p = ipv4()
> p.set_payload(u)
> p.srcip =IPAddr(i)#i is increased ip address such as 192.168.0.1,
> 192.168.0.2, 192.168.0.3, ... 192.168.1.255 ...
> p.dstip = IPAddr("192.168.56.100")
> e =ethernet (...)
> e.set_payload(p)
> #get a match from packet and tries to install a new rule...
> msg = of.ofp_flow_mod()
> msg.match = of.ofp_match.from_packet(packet, event.port)
> msg.idle_timeout = 10
> msg.hard_timeout = 30
> msg.actions.append(of.ofp_action_output(port = port))
> self.connection.send(msg)
> Till now, the results is what I expected-- a set of new rules are installed
> in the flow table;
>
> Next, I want to modify the installed (newly installed rules). At the same
> time, I want to send out a packet which matches a particular rules so that I
> know that modified rule takes effect.
>
> The code is like this--
> #repeat the "flow generate-- simulated flows" procedure
> ...
> #
> #get a match from packet and tries to modify that rule...
>
> msg = of.ofp_flow_mod()
> msg.command = of.OFPFC_MODIFY (make sure that this command is for
> modification)
> msg.match = of.ofp_match.from_packet(packet, event.port)
> msg.idle_timeout = 10
> msg.hard_timeout = 30
> msg.data = e.pack()
> msg.actions.append(of.ofp_action_output(port = port))
> self.connection.send(msg)
> Now, I get the error:
> ********error message*****************
> File "/home/sdn/pox/pox/openflow/of_01.py", line 687, in send
> data = data.pack()
> File "/home/sdn/pox/pox/openflow/libopenflow_01.py", line 2191, in pack
> self.buffer_id = self.data.buffer_id
> *********error message end**********
>
> I tested that If I change msg = of.ofp_flow_mod() to msg =
> of.ofp_packet_out(), it is fine. But I do not just want to send packet out.
> What I want to do is, first modify a rule and then send out a packet matching
> that rule.
>
>
> Can anyone help on the error? Thanks:)
> AttributeError: 'str' object has no attribute 'buffer_id'
>
>
