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Timestamp:: 10/03/13 11:41:26 (11 years ago)
Author:: lnevers@bbn.com
Comment:: --

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GENIExperimenter/Tutorials/OpenFlowOVS/Execute

-                      v39
+                      v40
 === 2b. Configure  the Software Switch ===
+Now that you are logged in, we need first to configure OVS. To save time in this tutorial, we have already started OVS and we have added an Ethernet bridge that will act as our software switch. Try:
+Now that you are logged in, we need first to configure OVS. To save time in this tutorial, we have already started OVS and we have added an Ethernet bridge that will act as our software switch. Try the following to show the configure bridge:
 {{{
 sudo ovs-vsctl list-br
 …
 ==== `standalone` vs `secure` mode ====
 The !OpenFlow controller is responsible for setting up all flows on the switch, which means that when the controller is not running there should be no packet switching at all. Depending on the setup of your network, such a behavior might not be desired. It might be best that when the controller is down, the switch should default back in being a learning layer 2 switch. In other circumstances however this might be undesirable. In OVS this is a tunable parameter, called `fail-safe-mode` which can be set to the following parameters:
   * `standalone` [default] : in which case OVS will take responsibility for forwarding the packets if the controller fails
   * `secure` : in which case only the controller is responsible for forwarding packets, and if the controller is down all packets are going to be dropped.
+  * `standalone` [default]: in which case OVS will take responsibility for forwarding the packets if the controller fails
+  * `secure`: in which case only the controller is responsible for forwarding packets, and if the controller is down all packets are going to be dropped.
 In OVS when the parameter is not set it falls back to the `standalone` mode. For the purpose of this tutorial we will set the `fail-safe-mode` to `secure`, since we want to be the ones controlling the forwarding. Run:
 …
 sudo ovs-vsctl set-fail-mode br0 secure
 }}}
 You can verify your OVS settings by issueing the following:
+You can verify your OVS settings by issuing the following:
 {{{
 sudo ovs-vsctl show
 }}}
 == 3. Execute Experiment ==
+Now that our switch is up and running we are ready to start working on our controller. For this tutorial we are going to use the [http://www.noxrepo.org/pox/about-pox/ POX controller]. The software that is installed in the OVS host for running POX can be found [http://www.gpolab.bbn.com/experiment-support/OpenFlowOVS/of-ovs.tar.gz here].
+Now that our switch is up and running we are ready to start working on our controller. For this tutorial we are going to use the [http://www.noxrepo.org/pox/about-pox/ POX controller]. The software is already installed in the OVS host for running POX and can also be found [http://www.gpolab.bbn.com/experiment-support/OpenFlowOVS/of-ovs.tar.gz here].
 === 3a. Login to your hosts ===
 To start our experiment we need to ssh all of our hosts. Depending on which tool and OS you are using there is a slightly different process for logging in. If you don't know how to SSH to your reserved hosts take a look in [wiki:HowTo/LoginToNodes this page.] Once you have logged in follow the rest of the instructions.
 …
 === 3b. Use a Learning Switch Controller ===
 We have installed the POX controller under `/local/pox` on the OVS host. POX comes with a set of example modules that you can use out of the box. One of the modules is a learning switch. Let's start the learning switch controller:
 {{{
 cd /local/pox
 ./pox.py --verbose forwarding.l2_learning
 }}}
 Go back to the terminal of `host1` and try to ping `host2` again:
 {{{
 ping 10.10.1.2
 }}}
 Now the ping should work.
 …
 Kill your POX controller by pressing `Ctrl-C`:
+{{{
+{{{
 DEBUG:forwarding.l2_learning:installing flow for 02:c7:e8:a7:40:65.1 -> 02:f1:ae:bb:e3:a8.2
  ^C
 …
 === Useful Tips for writing your controller ===
 In order to make this first experience of writing controller easier, we wrote some helpful functions that will abstract some of the particularities of POX away.
 These functions are locates at `/local/pox/ext/utils.py`, so while you write your controller consult this file for details.
 …
 === 3c. Run a traffic duplication controller ===
+In the above example we ran a very simple controller. The power of OpenFlow comes from the fact that you can decide to forward the packet anyway you want based on the supported OpenFlow actions. A very simple but powerful modification you can do, is to duplicate all the traffic of the switch out a specific port. This is very useful for application and network analysis. You can imagine that at the port where you duplicate traffic you connect a device that does analysis. Our hosts are VMs so we are going to verify the duplication by doing a `tcpdump`  on the port on the OVS switch.
+In the above example we ran a very simple learning switch controller. The power of !OpenFlow comes from the fact that you can decide to forward the packet anyway you want based on the supported !OpenFlow actions. A very simple but powerful modification you can do, is to duplicate all the traffic of the switch out a specific port. This is very useful for application and network analysis. You can imagine that at the port where you duplicate traffic you connect a device that does analysis. For this tutorial we  are going to verify the duplication by doing a `tcpdump`  on a port on the OVS switch.
 . Open two new terminals to the OVS host.
 . Look at the sliver details page in the portal and see what interfaces are bound to ''OVS:if0'' and ''OVS:if1'', use the MAC address of the interface to figure this out. Run tcpdump on these interfaces; one in each of the new terminals you opened. This will allow you to see all traffic going out the interfaces
+. Look at the slice ''Details'' page in the portal and see what interfaces are bound to ''OVS:if0'' and ''OVS:if1'', use the MAC address of the interface to figure this out. Run tcpdump on these interfaces; one in each of the new terminals you opened. This will allow you to see all traffic going out the interfaces.
   {{{
   sudo tcpdump -i <data_interface_name>
 …
 Now let's do a slightly more complicated controller. OpenFlow gives you the power to overwrite fields of your packets at the switch, for example the TCP source or destination port and do port forwarding. You can have clients trying to contact a server at port 5000, and the OpenFlow switch can redirect your traffic to a service listening on port 6000.
 Under the `/loca/pox/ext` directory there are two files !PortForwarding.py and myPortForwarding.py that are similar like the previous exercise. Both of these controller are configured by a configuration file at `ext/port_forward.config`. Use myPortForwarding.py to write your own port forwarding controller.
 To test your controller we are going to use netcat. Go to the two terminals of host2. In one terminal run:
+. Under the `/loca/pox/ext` directory there are two files !PortForwarding.py and myPortForwarding.py that are similar like the previous exercise. Both of these controller are configured by a configuration file at `ext/port_forward.config`. Use myPortForwarding.py to write your own port forwarding controller.
+. To test your controller we are going to use netcat. Go to the two terminals of host2. In one terminal run:
 {{{
 nc -l 5000
 …
 }}}
+Now, first start the simple layer 2 forwarding controller:
+{{{
+. Now, start the simple layer 2 forwarding controller. We are doing this to seen what happens with a simple controller.
+{{{
+cd /local/pox
 ./pox.py --verbose forwarding.l2_learning
 }}}
 Go to the terminal of host1 and connect to host2 at port 5000:
+. Go to the terminal of host1 and connect to host2 at port 5000:
 {{{
 nc 10.10.1.2 5000
 }}}
 Type something and you should see it at the the terminal of host2 at port 5000.
 Now stop the simple layer 2 forwarding controller:
+. Type something and you should see it at the the terminal of host2 at port 5000.
+. Now, stop the simple layer 2 forwarding controller:
 {{{
 DEBUG:forwarding.l2_learning:installing flow for 02:d4:15:ed:07:4e.3 -> 02:ff:be:1d:19:ea.2
 …
 }}}
 Now start your port forwarding controller:
+. And start your port forwarding controller:
 {{{
 ./pox.py --verbose myPortForwarding
 }}}
 Repeat the netcat scenario described above. Now, your text should appear on the other terminal of host2.
 Stop your port forwarding controller:
+. Repeat the netcat scenario described above. Now, your text should appear on the other terminal of host2 which is listenign to port 6000.
+. Stop your port forwarding controller:
 {{{
 DEBUG:myPortForwarding:Got a packet : [02:aa:a3:e8:6c:db>33:33:ff:e8:6c:db IPV6]
 …
 }}}
 === 3e. Run a server proxy Controller ===
+=== 3e. Run a Server Proxy Controller ===
 As our last exercise, instead of diverging the traffic to a different server running on the same host, we will diverge the traffic to a server running on a different host and on a different port.
+Under the `ext` directory there are two files Proxy.py and myProxy.py that are similar like the previous exercise. Both of these controllers are configured by a configuration file at `ext/proxy.config`.
 . On the terminal of `host3` run a netcat server:
   {{{
   nc -l 7000
   }}}
 . On your OVS host open the /local/pox/ext/P/myProxy.py file, and edit it to implement a controller that will diverge traffic destined for `host2` to `host3`. Before you start implementing think about what are the side effects of diverging traffic to a different host.
+. Under the `/loca/pox/ext` directory there are two files Proxy.py and myProxy.py that are similar like the previous exercise. Both of these controllers are configured by the configuration file `proxy.config`. Use myProxy.py to write your own proxy controller.
+. On the terminal of `host3` run a netcat server:
+{{{
+nc -l 7000
+}}}
+. On your OVS host open the /local/pox/ext/myProxy.py file, and edit it to implement a controller that will diverge traffic destined for `host2` to `host3`. Before you start implementing think about what are the side effects of diverging traffic to a different host.
      * Is it enough to just change the IP address?
      * Is it enough to just modify the TCP packets?
+  If you want to see the solution, it's available in file /local/pox/ext/Proxy.py file.
+. If you want to see the solution, it's available in file /local/pox/ext/Proxy.py file.
+. To test your proxy controller run:
+  {{{
+  ./pox.py --verbose myProxy
+  }}}
+. Go back to the terminal of `host1` and try to connect to `host2` port 5000
+  {{{
+  nc 10.10.1.2 5000
+  }}}
+. If your controller works correctly, you should see your text showing up on the terminal of `host3`.
+. To test your proxy controller run:
+{{{
+cd /local/pox
+./pox.py --verbose myProxy
+}}}
+. Go back to the terminal of `host1` and try to connect netcat to `host2` port 5000
+{{{
+nc 10.10.1.2 5000
+}}}
+. If your controller works correctly, you should see your text showing up on the terminal of `host3`.
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