Changes between Version 41 and Version 42 of GENIRacksHome/OpenGENIRacks/RaspberryPIs

Timestamp:

06/06/16 13:41:58 (8 years ago)

Author:

rrhain@bbn.com

Comment:

--

GENIRacksHome/OpenGENIRacks/RaspberryPIs

@@ -280 +280 @@
 
 ==== Running OVS and RYU on the PI's (Li Lin's work) ====
+
+
+{{{
+OpenFlow on RPi
+Li Lin, Regina Hain
+
+The goal of this work is to run an OpenFlow controller on a raspberry pi.
+To do so, we used Open vSwitch to configure the virtual switches on the
+pi server and Ryu to run the controller and to inject custom flows.
+
+There are three major pieces of this project:
+1. Use OVS to setup a useful and interesting network
+2. Run a custom script with the Ryu controller to install flows and route packets
+3. Demoing the system with a streaming webcam application
+
+==Part I: Using OVS to set up a useful and interesting network==
+
+=Topology=
+ _______________________________________________________________________
+|Pi Server                                                              |
+|   ____________         _______________         _______________        |
+|  |    BR1     |       |     BR2       |       |     BR3       |       |
+|  |  10.10.1.1 |  PP*  |   10.10.2.1   |  PP*  |  10.10.3.1    |       |
+|  |           2|-------|2             3|-------|2              |       |
+|  |_____1______|       |______1________|       |______1________|       |
+|   _____|______         ______|________         ______|________        |
+|  |eth1        |       |eth2           |       |eth3           |       |
+|  |10.10.1.x   |       |10.10.2.x      |       |10.10.3.x      |       |
+|  |____________|       |_______________|       |_______________|       |
+|        |                     |                       |                |
+|        |                     |                       |                |
+|________|_____________________|_______________________|________________|
+         |                     |                       |
+    _____|______         ______|________         ______|________
+   |    Pi1     |       |     Pi2       |       |     Pi3       |
+   | 10.10.1.2  |       |  10.10.2.2    |       |  10.10.3.2    |
+   |____________|       |_______________|       |_______________|
+
+
+*: PP means patch port
+
+=Description=
+This setup consists of 4 pi's- one acting as a server 3 as the clients.
+There are 3 accompanying interfaces on the server- eth1, eth2, eth3, each
+their own subnet. Additionally, each is connected to a separate OVS bridge.
+The OVS bridges forward packets to all other bridges via patch ports.
+
+=Setup on server=
+To configure this network, run configure_pt1
+
+=Setup on client=
+To configure the ip address of client pi's, add the following
+lines to /etc/dhcpcd.conf depending on its ip address and router values
+
+# In pi1 /etc/dhcpcd.conf
+interface eth0
+static ip_address=10.10.1.2/24
+static router=10.10.1.1
+
+# In pi2 /etc/dhcpcd.conf
+interface eth0
+static ip_address=10.10.2.2/24
+static router=10.10.2.1
+
+
+# In pi3 /etc/dhcpcd.conf
+interface eth0
+static ip_address=10.10.3.2/24
+static router=10.10.3.1
+
+=Test=
+To test, run ping from one client Pi to another client Pi. Connectivity
+should be present, via the OVS bridge and patch port topology, between
+all three client Pi's.
+
+=Teardown=
+To teardown this network, run teardown_pt1
+
+
+==Part II: Using Ryu to install flows and route packets over our OVS network==
+
+=Topology=
+ _______________________________________________________________________
+|Pi Server                                                              |
+|   ____________________________________________________________        |
+|  |                            BR1                             |       |
+|  |                         10.10.1.10                         |       |
+|  |                                                            |       |
+|  |_____1_____________________3_______________________2________|       |
+|   _____|______         ______|________         ______|________        |
+|  |eth1        |       |eth2           |       |eth3           |       |
+|  |10.10.1.1   |       |10.10.1.3      |       |10.10.1.2      |       |
+|  |____________|       |_______________|       |_______________|       |
+|        |                     |                       |                |
+|        |                     |                       |                |
+|________|_____________________|_______________________|________________|
+         |                     |                       |
+    _____|______         ______|________         ______|________
+   |    Pi1     |       |     Pi2       |       |     Pi3       |
+   | 10.10.1.4  |       |  10.10.1.5    |       |  10.10.1.6    |
+   |____________|       |_______________|       |_______________|
+
+Note that this topology is different from that in part I. This is because
+having 3 bridges added too much unneeded complexity when crafting custom
+flows. This time we used 1 bridge to connect all three interfaces and
+connecting them up through separate ports.
+
+=RYU Script Description=
+
+This script creates a custom flow that matches on any packet coming in
+on port 1 (source 10.10.1.4) and out on port 3 (destination 10.10.1.5).
+It forwards that packet as usual, but also
+creates a duplicate packet, modifies its destination (to the address
+of pi3) and sends to port 2 (pi 3). The result is that pi3 gets a copy
+of every packet that is sent from pi1 to pi2.
+
+Note that to turn on the special flow, *insert_special_flow* must be set to
+True in ryu_13_custom.py
+
+To see that the custom flow is installed correctly (note that installation
+will occur only on the first instance of a packet with source 10.10.1.4
+and destination 10.10.1.5 captured by our controller), on the server type
+$ sudo ovs-ofctl dump-flows br1
+
+
+=Setup=
+To configure this network, run configure_pt2
+Note that step 5, connecting the controller to the bridge, takes the
+ip address of the server's eth0 interface. This can change based on
+network and pi. To find the correct ip address to use, in a terminal type
+$ ifconfig -a
+
+=Run=
+To run the ryu controller with our custom script type:
+$ ryu-manager ./path/to/ryu_13_custom.py
+To ensure controller connectivity type:
+$ sudo ovs-vsctl show
+and you should see something like this (if connected):
+    Bridge "br1"
+        Controller "tcp:128.89.68.110:6633"
+            is_connected: true
+
+=Testing=
+
+Ping test
+On 10.10.1.4 (pi1) type
+$ ping 10.10.1.5
+You will see that 2 different hosts will reply to the pings- both
+pi2 (10.10.1.5) and pi3 (10.10.1.6).
+
+Netcat test
+On 10.10.1.5 (pi2) type
+$ nc -l 1234
+On 10.10.1.6 (pi3) type
+$ nc -l 1234
+On 10.10.1.4 (pi1) type
+$ echo "HELLO WORLD" | nc 10.10.1.5 1234 -u
+
+You should see that HELLO WORLD should be printed on both pi2 and pi3.
+This only works in udp mode (-u) and the reason is left as an
+exercise for the reader.
+
+=Teardown=
+To teardown this network, run teardown_pt2
+
+
+==Part III: Demoing via a streaming webcam application==
+
+In this demo, pi1 (10.10.1.4) will send raw video bytes captured from
+its webcam to pi2 (10.10.1.5) via the netcat application. Pi2 will capture
+the udp packets by using netcat to listen on a specified port and save
+the data to a pipe file. Pi2 will then run mplayer on the file to output the
+video to screen. Pi3 will perform the same exact functions as Pi2, and
+since the controller sends a duplicate copy of every udp packet to Pi3,
+it can receive and render the webcam video also.
+
+On Pi1:
+1. Compile the C file used to read data from the webcam
+$ gcc capturevideo.c -o capturevideo
+2. Execute and pipe the output to 10.10.1.5 via netcat
+$ ./capturevideo -c 1000 -o | nc 10.10.1.5 5000
+*. Instructions and code taken from: https://www.raspberrypi.org/forums/viewtopic.php?t=98778&p=685576
+
+On Pi2:
+1. If not installed already, install mplayer
+$ sudo apt-get install mplayer
+2. Create a pipe file
+$ mkfifo video.fifo
+3. Call netcat and listen to specified port
+$ nc.traditional -lu -p 5000 > video.fifo
+4. Use mplayer to open video
+$ mplayer video.fifo -demuxer rawvideo -rawvideo w=640:h=480:format=yuy2
+
+On Pi3:
+1. If not installed already, install mplayer
+$ sudo apt-get install mplayer
+2. Create a pipe file
+$ mkfifo video.fifo
+3. Call tcpdump to listen to specified port
+$ sudo tcpdump -i eth0 udp port 5000 -w video.fifo
+Note: Netcat will not accept packets because it requires a connection,
+even when solely listening for udp packets, when the datagram size is over
+1500 bytes.
+4. Use mplayer to open video
+$ mplayer video.fifo -demuxer rawvideo -rawvideo w=640:h=480:format=yuy2
+}}}
+