WikiStart: FirstSDNApplication.md

% SDN / OpenFlow tutorial
%
% First SDN Application

# Introduction 

In this lab we will connect write our first SDN application and run it on the controller.

# Goals

* Write an SDN application using the Ryu framework
* Start the application on the controller.

# Notes

* Commands preceded with "$" imply that you should execute the command as
  a general user - not as root.
* Commands preceded with "#" imply that you should be working as root.
* Commands with more specific command lines (e.g. "RTR-GW>" or "mysql>") 
  imply that you are executing commands on remote equipment, or within 
  another program.

# Installation

## A very simple switch.

Open up a terminal on the controller and create the following file

    $ vi ~/l2.py

It should contain the following

        from ryu.base import app_manager
        from ryu.controller import mac_to_port
        from ryu.controller import ofp_event
        from ryu.controller.handler import MAIN_DISPATCHER
        from ryu.controller.handler import set_ev_cls
        from ryu.ofproto import ofproto_v1_3
        from ryu.lib.mac import haddr_to_bin
        from ryu.lib.packet import packet
        from ryu.lib.packet import ethernet
    
        class L2Switch(app_manager.RyuApp):
            def __init__(self, *args, **kwargs):
                super(L2Switch, self).__init__(*args, **kwargs)
    
            @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
            def packet_in_handler(self, ev):
                msg = ev.msg
                dp = msg.datapath
                ofp = dp.ofproto
                ofp_parser = dp.ofproto_parser
                in_port = msg.match['in_port']
    
                actions = [ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD)]
                out = ofp_parser.OFPPacketOut(
                    datapath=dp, buffer_id=msg.buffer_id, in_port=in_port,
                    actions=actions)
                dp.send_msg(out)


With one window open on your controller, and the other window on your datapath element, start this application on the controller with the following command.

    $ ryu-manager --verbose ~/l2.py

Then run the following on the datapath element

        # /root/bootovs-rb532.sh 


Once everything has started you can confirm that the datapath element has contacted the controller

    2014-01-28T04:56:02Z|00030|rconn|INFO|br0<->tcp:10.10.0.1:6633: connected

Every time a packet arrives on either of the datapath ports the following message will be printed on the controller screen

        EVENT ofp_event->L2Switch EventOFPPacketIn
        EVENT ofp_event->L2Switch EventOFPPacketIn
        EVENT ofp_event->L2Switch EventOFPPacketIn
        EVENT ofp_event->L2Switch EventOFPPacketIn
        EVENT ofp_event->L2Switch EventOFPPacketIn
        EVENT ofp_event->L2Switch EventOFPPacketIn

You can confirm this by having someone plug a laptop into the rb532


## A more complicated switch

    git clone https://code.google.com/r/dean-nsss/

    ryu-manager --verbose ./dean-nsss/simple_switch_13.py


On the datapath element run the monitor_flows command   

        $ ./monitor_flows.sh

This should give the  output similar to the following

        Tue Jan 28 05:01:57 UTC 2014
        OFPST_FLOW reply (OF1.3) (xid=0x2):
         cookie=0x0, duration=10.535s, table=0, n_packets=27, n_bytes=4624, priority=1,in_port=1,dl_src=3c:07:54:49:ee:97 actions=goto_table:1
         cookie=0x0, duration=93.21s, table=1, n_packets=3, n_bytes=1026, priority=10,dl_dst=ff:ff:ff:ff:ff:ff actions=ALL
         cookie=0x0, duration=93.21s, table=1, n_packets=0, n_bytes=0, priority=5,dl_type=0x88cc actions=drop
         cookie=0x0, duration=93.21s, table=1, n_packets=0, n_bytes=0, priority=5,dl_type=0x05ff actions=drop
         cookie=0x0, duration=93.21s, table=1, n_packets=15, n_bytes=3058, priority=11,dl_dst=33:33:00:00:00:00/ff:ff:00:00:00:00 actions=ALL
         cookie=0x0, duration=93.21s, table=1, n_packets=0, n_bytes=0, priority=10,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 actions=ALL
         cookie=0x0, duration=93.21s, table=1, n_packets=9, n_bytes=540, priority=0 actions=FLOOD,CONTROLLER:64
        
--End