RyuBook1.0 case Three: REST Linkage

REST Linkage

This summary describes how to add a rest Link function

The Ryu itself provides a Web server function similar to WSGI. With this feature, we can create a rest API.
Based on the rest API created, the Ryu system can be quickly connected to other systems or browsers, which is a very useful feature.

Program parsing

In the case, two classes were implemented

• SimpleSwitchRest13
  • Inherits the functionality of the SimpleSwitch13, which is the basic functionality of a three-layer switch with a parent class.
  • Register WSGI Service
  • Configure Mac_to_port
• Simpleswitchcontroller
  • The principal class for the REST API feature implementation
  • Returns the mac_table of the specified switch
  • Update the specified Mac_table entry

SimpleSwitchRest13 class implementation

_CONTEXTS = {'wsgi': WSGIApplication}

This member variable is used to indicate the Ryu compatible WSGI Web service object.

wsgi = kwargs['wsgi']wsgi.register(SimpleSwitchController,              {simple_switch_instance_name: self})

The member variables that are set in the previous step _CONTEXTS can be kwargs instantiated by a wsgiapplication. Use register the same method to register the service to
Controller class.

@set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)def switch_features_handler(self, ev):    super(SimpleSwitchRest13, self).switch_features_handler(ev)    datapath = ev.msg.datapath    self.switches[datapath.id] = datapath    self.mac_to_port.setdefault(datapath.id, {})

Overriding a function of the parent class switch_features_handler

• Storage DataPath toswitches
• Initializing the MAC Address table

def set_mac_to_port (self, Dpid, entry): # get mac Table mac_table = Self.mac_to_port.setdefault (Dpid, {}) # get D    Atapath, if none, proves that there is no switch datapath = Self.switches.get (dpid) entry_port = entry[' Port '] Entry_mac = entry[' mac '] If DataPath is not none:parser = datapath.ofproto_parser # if Entry_port isn't in mac_table if Entry_port Not in Mac_table.values (): # issued stream table for Mac, Port in Mac_table.items (): # from Known de Vice to new device actions = [parser. Ofpactionoutput (entry_port)] match = parser. Ofpmatch (In_port=port, Eth_dst=entry_mac) Self.add_flow (DataPath, 1, match, actions) # from New device to known device actions = [parser. Ofpactionoutput (port)] Match = parser. Ofpmatch (In_port=entry_port, Eth_dst=mac) Self.add_flow (DataPath, 1, match, actions) # Add Entry_m AC, entry_port to mac_table mac_tablE.update ({entry_mac:entry_port}) return mac_table 

This method registers the MAC address and port with the specified switch. This method is primarily called by the put method of the rest API.

Simpleswitchcontroller class implementation

@route('simpleswitch', url, methods=['GET'],           requirements={'dpid': dpid_lib.DPID_PATTERN})

routeassociate methods and URLs with adorners. The parameters are as follows:

• First parameter: Any custom name
• Second parameter: Indicates the URL
• Third parameter: Specify the HTTP method
• Fourth parameter: Indicates the format of the specified location, the URL (/simpleswitch/mactable/{dpid} matches DPID_PATTERN the description

Call the List_mac_table function when you access the rest API interface by using GET mode

def list_mac_table(self, req, **kwargs):    simple_switch = self.simple_switch_app    # 获取{dpid}    dpid = dpid_lib.str_to_dpid(kwargs['dpid'])        # 如果没有dpid,返回404    if dpid not in simple_switch.mac_to_port:        return Response(status=404)    # 获取mac_table    mac_table = simple_switch.mac_to_port.get(dpid, {})    body = json.dumps(mac_table)    return Response(content_type='application/json', body=body)

# 使用PUT方式设置mac_table@route('simpleswitch', url, methods=['PUT'],           requirements={'dpid': dpid_lib.DPID_PATTERN})    def put_mac_table(self, req, **kwargs):        simple_switch = self.simple_switch_app        dpid = dpid_lib.str_to_dpid(kwargs['dpid'])        try:            new_entry = req.json if req.body else {}        except ValueError:            raise Response(status=400)        if dpid not in simple_switch.mac_to_port:            return Response(status=404)        try:            mac_table = simple_switch.set_mac_to_port(dpid, new_entry)            body = json.dumps(mac_table)            return Response(content_type='application/json', body=body)        except Exception as e:            return Response(status=500)

Run analysis

Start mininet Create a network topology diagram

sudo mn --topo single,3 --mac --switch ovsk,protocols=OpenFlow13 --controller remote -x

Start the controller program and print the log information as follows:

debugging is available (--enable-debugger option is turned on)loading app SimpleSwitchRest13loading app ryu.controller.ofp_handlercreating context wsgiinstantiating app SimpleSwitchRest13 of SimpleSwitchRest13instantiating app ryu.controller.ofp_handler of OFPHandlerBRICK SimpleSwitchRest13  CONSUMES EventOFPPacketIn  CONSUMES EventOFPSwitchFeaturesBRICK ofp_event  PROVIDES EventOFPPacketIn TO {'SimpleSwitchRest13': set(['main'])}  PROVIDES EventOFPSwitchFeatures TO {'SimpleSwitchRest13': set(['config'])}  CONSUMES EventOFPEchoReply  CONSUMES EventOFPSwitchFeatures  CONSUMES EventOFPPortDescStatsReply  CONSUMES EventOFPHello  CONSUMES EventOFPErrorMsg  CONSUMES EventOFPEchoRequest  CONSUMES EventOFPPortStatus(22238) wsgi starting up on http://0.0.0.0:8080

Here we can see that the WSGI service has been started with a port number of 8080

Query the default Mac table for S1

curl -X GET http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

Return to{}

Execute in Mininet

mininet> h1 ping -c 1 h2

The log information prints the following information:

EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 ff:ff:ff:ff:ff:ff 1EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:02 00:00:00:00:00:01 2EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 00:00:00:00:00:02 1

Three Packagein messages returned (ARP procedure)

1. Host1 initiates an ARP request and broadcasts
2. Host2 initiated ARP request, MAC address is host1
3. ICMP Echo Reply request takes place from Host1 to Host2

Now by design, two entries have been added to Mac table, and the query is verified again.

curl -X GET http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

Return as follows to demonstrate compliance with experimental expectations:

{"00:00:00:00:00:02": 2, "00:00:00:00:00:01": 1}

Test Post API interface, add H3 to Mac Table

curl -X PUT -d '{"mac" : "00:00:00:00:00:03", "port" : 3}' http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

Return:

{"00:00:00:00:00:03": 3, "00:00:00:00:00:02": 2, "00:00:00:00:00:01": 1}

Prove that the H3 Mac has been added to Mac table. Because H3 has been added to Mac table, it is theoretically not possible to find H3 through ARP when H1 ping H3.

Testing: Executing commands in Mininet

mininet> h1 ping c1 h3PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data.64 bytes from 10.0.0.3: icmp_seq=1 ttl=64 time=2.48 ms--- 10.0.0.3 ping statistics ---1 packets transmitted, 1 received, 0% packet loss, time 0msrtt min/avg/max/mdev = 2.480/2.480/2.480/0.000 ms

The controller log information is as follows:

EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 ff:ff:ff:ff:ff:ff 1

We can see that only H1, without knowing the H3 address, initiates an ARP broadcast that sends Packagein messages to the controller without any subsequent series of messages. This proves that the entries added to the
MAC table are successful, as expected.