Changes between Version 3 and Version 4 of GEC15Agenda/AdvancedGENITopoOmni/Instructions/L3DeflectExperiment

Timestamp:

10/21/12 21:46:54 (12 years ago)

Author:

nriga@bbn.com

Comment:

--

GEC15Agenda/AdvancedGENITopoOmni/Instructions/L3DeflectExperiment

@@ -170 +170 @@
   }}}
 
-== 4. Turn off internet protocol ==
-
-At this point, your network is still running IP. You can check by running a ping. In your '''hosta''' terminal window, run this command.
-
+=== 4b. Modify the configuration file of the OpenFlow controller ===
+By now your ProtoGENI host should have been configured. Let's login to the node and modify the configuration file of our OpenFlow controller. 
+  i. Open a new terminal and login to the ProtoGENI host:
+  {{{
+ssh ofctrl
+}}}
+  i. Run :
+  {{{
+  ps -ef | grep nox_core
+}}}
+  The output should look like:
+  {{{
+root      6498     1  0 18:33 ?        00:00:01 /usr/local/bin/noxgpo/src/.libs/lt-nox_core -d -i ptcp:6633 switch
+inki      6562  6524  0 18:45 pts/0    00:00:00 grep nox_core
+}}}
+  If the first line is missing then the setup has not finished yet. You can move to the next step, but make sure the setup has finished before moving to step 5. 
+  i. Copy the configuration file to your home directory:
+  {{{
+  cp /local/l3deflect.conf ~/
+  }}}
+  i. Modify the configuration file to match the information in your slip. The should look like:
+  {{{
+# Configuration file for the l3deflect controller
+
+[general]
+orig_mac = 00:1B:21:4B:3E:E9
+orig_ip = 10.42.123.52
+deflect_mac = 00:1B:21:4B:3F:AD
+deflect_ip = 10.42.123.51
+}}}
+== 5. Run the experiment ==
+Now we have reserved and configured all hosts. We are ready to run our experiment. 
+  i. In the terminal of the remote and of the local server run the following command. Substitute <NC_PORT> with the information in your slip:
+  {{{
+  nc <nc_port>
+}}}
+   i. In the terminal of the client run this command, using your paper slip to fill in the information :
+  {{{
+  nc <IP_REMOTE_SERVER> <NC_PORT>
+}}}
+  i. You now have a chat application between the remote server and the client. Try typing something in the client and see it pop up at the server side, and vice versa. The forwarding of your packets work because there is a default learning switch controller running on your ProtoGENI host. 
+  i. Let's stop the default learning switch controller and start our deflection controller. In a local terminal type the following two commands:
+  {{{
+   ssh ofctrl "/usr/local/bin/stop-all-ctrls.sh"
+   ssh ofctrl "/usr/local/bin/start-ctrl.sh l3deflect"
+  }}}
+  The output should look like that:
+  {{{
+nriga@pella:~$ ssh ofctrl "/usr/local/bin/stop-all-ctrls.sh"
+Stopping all OpenFlow controllers
+nriga@pella:~$ ssh ofctrl "/usr/local/bin/start-ctrl.sh l3deflect"
+Starting OpenFlow controler l3deflect
+  }}}
+  i. If the `nc` is still running on the client, terminate it by pressing `Ctrl-C`. 
+  i Run the `nc` at the client again:
+  {{{
+ nc <IP_REMOTE_SERVER> <NC_PORT>
+}}}
+  i Type something on the client and notice in which terminal it appears. 
+
+If you want to switch back to the switch controller you need to again kill all the controllers and start the switch controller :
 {{{
-ping -c 3 hostb
-}}}
-
-The command should succeed, with output like this:
-
-{{{
-PING hostB-link-B (10.10.6.2) 56(84) bytes of data.
-64 bytes from hostB-link-B (10.10.6.2): icmp_seq=1 ttl=61 time=1.38 ms
-64 bytes from hostB-link-B (10.10.6.2): icmp_seq=2 ttl=61 time=1.19 ms
-64 bytes from hostB-link-B (10.10.6.2): icmp_seq=3 ttl=61 time=1.53 ms
-
---- hostB-link-B ping statistics ---
-3 packets transmitted, 3 received, 0% packet loss, time 2004ms
-rtt min/avg/max/mdev = 1.193/1.370/1.531/0.138 ms
-}}}
-
-Since our experiment doesn't want IP, let's turn it off :
-  i. On a local terminal run the following command four time, each time substituting the <router_nickname> with one of the top, bottom, left, right:
-  {{{
-  ssh -A <router_nickname> "sh ./stopIP.sh"
-}}}
-
-  You'll get output like this (the interface names may be different):
-  {{{
-Disabling IP on interface mv10.9
-Disabling IP on interface mv10.10
-}}}
-
-  i. Verify that IP is really off, try another ping. On '''hosta''':
-  {{{ 
-  ping -c 3 hostb
-}}}
-  The command should take twelve seconds to time out, then fail with output like this:
-  {{{
-PING hostB-link-B (10.10.6.2) 56(84) bytes of data.
-
---- hostB-link-B ping statistics ---
-3 packets transmitted, 0 received, 100% packet loss, time 11999ms
-}}}
-
-== 5. Start your routers ==
-
-The extractor script produces a click configuration file for each of your routers.  
-  i. On a local terminal run the following command four time, each time substituting the <router_nickname> with one of the top, bottom, left, right:
-  {{{
-  ssh -A <router_nickname> "sh ./startClick.sh"
-}}}
-  You'll get output like this. (Don't worry about the warning messages, Click is just reminding you that you have no IP addresses in your core network.) The output of the click router is redirected to `/tmp/click.out` on each host. 
-
-  {{{
-Stopping any running Click routers
-Starting Click router
-top.click:34: While initializing ‘FromDevice@18 :: FromDevice’:
-  warning: eth2: no IPv4 address assigned
-top.click:35: While initializing ‘FromDevice@21 :: FromDevice’:
-  warning: eth4: no IPv4 address assigned
-}}}
-
-Congratulations! You are now running a non-IP core network on your four routers, along with a (primitive) non-IP multipath routing algorithm. You're ready to experiment with this configuration.
-
-== 6. Send some traffic ==
-
-Now you'll use your two edge hosts, '''hostA''' and '''hostB''' to send traffic along your network.  Since these end hosts are not running your modified protocol, they'll rely on the '''top''' and '''bottom''' routers to transform their IP packets into your modified protocol on entry to the core network and back into IP packets on exit.
-  i. In your terminal window on '''hostB''', instruct '''nc''' to listen for a UDP connection on port 24565 (or some other port that catches your fancy).
-  {{{
-[mberman@hostb ~]$ nc -ul 24565
-}}}
-  i. Connect to it from your terminal window on '''hostA''':
-  {{{
-[mberman@hosta ~]$ nc -u hostb 24565
-}}}
-
-You've established a simple text chat connection. Enter a line of text in either window, and it should appear in the other. Of course to do this, the text is travelling through your core network, using your non-standard protocol and routing. So type a message into each window, and make sure it appears in the other.
-
-That's it!  Now, let's look inside to see what's going on.
-
-== 7. Looking under the hood ==
-
-Please note: the interface names and MAC addresses below are for the sample configuration shown in the figure above. You will want to refer to your network diagram to get the correct interfaces and addresses for your configuration.
-
-Let's take a look at what's happening in the four routers in your configuration. There are two basic router configurations. (You can find all of these files on any of your router hosts.)
-
-=== 7b. Packet transformation ===
-
-  i. The more interesting configuration appears here, in the '''top.click''' configuration file. In a local terminal type:
-  {{{
- ssh -A top "cat top.click"
-}}}
-  The output will look like : 
-  {{{
-// This portion accepts IP packets,
-// reformats them, and routes them
-// to an internal router.
-route :: Classifier(27/01%01,-);
-
-modify :: Unstrip(2) ->
-    StoreData(0, "AliceWasHere3546") ->
-    route;
-
-FromDevice(eth3, PROMISC true) -> 
-    Classifier(12/0800) ->
-    modify;
-
-route[0] -> left :: EtherEncap(0x7744, 00:04:23:b7:14:76, 00:04:23:b7:18:fa) ->
-    SimpleQueue ->
-    Print(outL) ->
-    ToDevice(eth2);
-
-route[1] -> right :: EtherEncap(0x7744, 00:04:23:b7:1c:e0, 00:04:23:b7:19:2e) ->
-    SimpleQueue ->
-    Print(outR) ->
-    ToDevice(eth4);
-
-// This portion accepts non-IP packets
-// with an ether type of 0x7744
-// from an internal router, restores
-// them to IP format, and forwards.
-restore :: SimpleQueue ->
-    Strip(30) ->
-    EtherEncap(0x800, 00:04:23:b7:14:77, 00:04:23:b7:20:00) ->
-    ToDevice(eth3);
-
-FromDevice(eth2) -> Classifier(12/7744) -> Print(inL) -> restore;
-FromDevice(eth4) ->  Classifier(12/7744) -> Print(inR) -> restore;
-}}}
-
-  As indicated in the comments, the top portion of the configuration listens ('''!FromDevice''') for IP packets arriving on the interface connected to '''hostA''' (that's '''eth3''' in this example). It then creates a new 16-byte field at the head of the packet (two bytes added by the '''Unstrip''' operation, plus the existing 14-byte Ethernet header. It fills that field with what could be important routing instructions, but in this case is just graffiti ('''!StoreData'''). The '''route''' operation then routes the packet via either the '''left''' or '''right''' router toward '''hostB'''. In either case, it wraps the packet in a fresh Ethernet header ('''!EtherEncap''') with a distinctive ether type code (0x7744), logs the new packet on its way out ('''Print''') and sends it out on the correct interface ('''!ToDevice''').
-
-  The bottom portion of the configuration is intended for packets coming out of the core network to '''hostA'''.  It accepts packets from either the '''left''' or '''right''' router, logs them, strips off thirty bytes (Ethernet header plus your 16-byte new header field), puts on a fresh Ethernet header, and sends them along to '''hostA'''.
-
-  The configuration for the '''bottom''' router is exactly symmetric, routing packets between '''hostB''' and the core network, but using different graffiti.
-
-=== 7b. Simple Forwarding ===
-
-The '''left''' router configuration is much simpler.  In a local terminal type:
-{{{
- ssh -A left "cat left.click"
-}}}
-  The output will look like : 
-
-{{{
-// Copy packets from top to bottom.
-FromDevice(eth2) ->
-    StoreEtherAddress(00:04:23:b7:42:b6, dst) ->
-    StoreEtherAddress(00:04:23:b7:18:fb, src) ->
-    SimpleQueue ->
-    Print(top) ->
-    ToDevice(eth3);
-// Copy packets from bottom to top.
-FromDevice(eth3) ->
-    StoreEtherAddress(00:04:23:b7:14:76, dst) ->
-    StoreEtherAddress(00:04:23:b7:18:fa, src) ->
-    SimpleQueue ->
-    Print(bottom) ->
-    ToDevice(eth2);
-}}}
-
-This configuration just blindly forwards packets. It picks up any packet from the '''top''' router, updates the Ethernet header, and passes it along to the '''bottom''' router. The same applies in the reverse direction.  Again, the configuration for the '''right''' router is exactly analogous.
-
-=== 7c. Monitoring your core network ===
-
-Let's watch how the packets travel through the network. 
-  i. In a local terminal type:
-  {{{
-  ssh -A top "tail -f /tmp/click.log"
-}}}
-  i. Go to your window for hostA, where your '''nc''' command is still running. Type a message into this window. You should see a log message in three of your four router windows. In this example, you might see:
-  i. In the local terminal you will see:
-  {{{
-outR:   76 | 000423b7 192e0004 23b71ce0 7744416c 69636557 61734865
-}}}
-  This log entry says that the '''top''' router received a packet from '''hostA''', modified it, and sent it out to the '''right''' router. If the entry started with '''outL''', that would indicate that it sent the packet out to the '''left''' router. Let's look a bit at the start of the packet (the first 24 bytes are logged). It starts with an Ethernet header. The first six bytes are the MAC address of the destination interface, that's 00:04:23:B7:19:2E, the MAC address of '''eth4''' on '''right'''. The next six bytes are the MAC address of the source interface, 00:04:23:B7:1C:E0, or '''eth4''' on '''top'''. Next comes your ether type, 0x7744. The remaining bytes, "416c 69636557 61734865" are the start of the first field in your new protocol, "!AliceWasHe" in ASCII.
-  i. Try typing a few different lines to hostA. You should see some packets routed to the left and some to the right. The routing decision is based on the '''route :: Classifier(27/01%01,-);''' entry in the '''top''' router configuration. Here, the router is looking at the low-order bit of the checksum on the initial IP packet (now at byte position 27 with the addition of the new sixteen byte field at the start of the header). Packets with odd checksums go to the left; those with even checksums go right.
-
-== 9. Clean up ==
+ ssh ofctrl "/usr/local/bin/stop-all-ctrls.sh"
+ ssh ofctrl "/usr/local/bin/start-ctrl.sh switch"
+}}}
+You can play switching between the two controllers and notice how the text appears on a different terminal. 
+
+== 6. Looking under the hood ==
+If you still have a few minutes, then you can poke around the OpenFlow controller, if you don't have enough time then make sure you move to the next step
+and cleanup your resources. You can always come back and do the tutorial again and poke around. 
+
+Congratulations you have successfully diverted the traffic from your client to the local server using OpenFlow!. But how did this work? Basically our openflow controller
+instructed the switch to rewrite the IP information on the packet so that 
+  * every packet that was destined to the original server, it would be changed to be sent to the local one
+  * also all packets from the local  server are rewritten so that the client thinks that it talks to the remote server. 
+
+Let's take a quick look at the controller. On the terminal that is logged in to the ProtoGENI host open file `/usr/local/src/noxgpo/src/nox/coreapps/example/l3deflect.py`. This is the deflection module. Lets try and follow the logic now:
+  i. Find the `install` function. This is the function that registers your module to receive OpenFlow events. 
+  i Look at which function is called when a packet is received. 
+  i. Ignore the first checks and find the function that is responsible for forwarding packets. 
+  i. Look at the logic that is overwriting the packet. Basically there is a section like this :
+  {{{
+        # Check if the eth_type must be deflected
+        if ethtype == 0x800 :
+          # and if the dst mac address is the one that should be deflected
+          if mac_to_str(packet.dst).lower() == self.orig_mac.lower() :
+            # replace the destination mac address 
+            actions.append([openflow.OFPAT_SET_DL_DST,
+                                octstr_to_array(self.deflect_mac)])
+            logger.debug("NEW DST MAC %s" % ( self.deflect_mac))
+            dstaddr = octstr_to_array(self.deflect_mac).tostring()
+            actions.append([openflow.OFPAT_SET_NW_DST,
+                                ipstr_to_int(self.deflect_ip)])
+            logger.debug("NEW DST IP %s" % ( self.deflect_ip))
+            logger.info("Packet %s is deflected")
+
+          if mac_to_str(packet.src).lower() == self.deflect_mac.lower() :
+            # replace the destination mac address 
+            actions.append([openflow.OFPAT_SET_DL_SRC,
+                                octstr_to_array(self.orig_mac)])
+            logger.debug("NEW SRC MAC %s" % ( self.orig_mac))
+            actions.append([openflow.OFPAT_SET_NW_SRC,
+                                ipstr_to_int(self.orig_ip)])
+            logger.debug("NEW DST IP %s" % ( self.orig_ip))
+  }}}
+== 7. Clean up ==
 
 When you're done, please release your resources so they'll be available to others.