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March 26, 2014 17:30
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# Copyright 2012 James McCauley | |
# | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at: | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
""" | |
This component is for use with the OpenFlow tutorial. | |
It acts as a simple hub, but can be modified to act like an L2 | |
learning switch. | |
It's roughly similar to the one Brandon Heller did for NOX. | |
""" | |
from pox.core import core | |
import pox.openflow.libopenflow_01 as of | |
log = core.getLogger() | |
class Tutorial (object): | |
""" | |
A Tutorial object is created for each switch that connects. | |
A Connection object for that switch is passed to the __init__ function. | |
""" | |
def __init__ (self, connection): | |
# Keep track of the connection to the switch so that we can | |
# send it messages! | |
self.connection = connection | |
# This binds our PacketIn event listener | |
connection.addListeners(self) | |
# Use this table to keep track of which ethernet address is on | |
# which switch port (keys are MACs, values are ports). | |
self.mac_to_port = {} | |
def resend_packet (self, packet_in, out_port): | |
""" | |
Instructs the switch to resend a packet that it had sent to us. | |
"packet_in" is the ofp_packet_in object the switch had sent to the | |
controller due to a table-miss. | |
""" | |
msg = of.ofp_packet_out() | |
msg.data = packet_in | |
# Add an action to send to the specified port | |
action = of.ofp_action_output(port = out_port) | |
msg.actions.append(action) | |
# Send message to switch | |
self.connection.send(msg) | |
def act_like_hub (self, packet, packet_in): | |
""" | |
Implement hub-like behavior -- send all packets to all ports besides | |
the input port. | |
""" | |
# We want to output to all ports -- we do that using the special | |
# OFPP_ALL port as the output port. (We could have also used | |
# OFPP_FLOOD.) | |
self.resend_packet(packet_in, of.OFPP_ALL) | |
# Note that if we didn't get a valid buffer_id, a slightly better | |
# implementation would check that we got the full data before | |
# sending it (len(packet_in.data) should be == packet_in.total_len)). | |
def act_like_switch (self, packet, packet_in): | |
""" | |
Implement switch-like behavior. | |
""" | |
self.mac_to_port[packet.src] = packet_in.in_port | |
if packet.dst in self.mac_to_port: | |
print("Packet sent to Control Plane") | |
# Send the packet to the destination | |
self.resend_packet(packet_in, | |
self.mac_to_port[packet.dst]) | |
# Install a flow | |
msg = of.ofp_flow_mod() | |
msg.match.dl_dst = packet.dst | |
msg.actions.append(of.ofp_action_output(port=self.mac_to_port[packet.dst])) | |
self.connection.send(msg) | |
else: | |
self.resend_packet(packet_in, of.OFPP_ALL) | |
def _handle_PacketIn (self, event): | |
""" | |
Handles packet in messages from the switch. | |
""" | |
packet = event.parsed # This is the parsed packet data. | |
if not packet.parsed: | |
log.warning("Ignoring incomplete packet") | |
return | |
packet_in = event.ofp # The actual ofp_packet_in message. | |
# Comment out the following line and uncomment the one after | |
# when starting the exercise. | |
#self.act_like_hub(packet, packet_in) | |
self.act_like_switch(packet, packet_in) | |
def launch (): | |
""" | |
Starts the component | |
""" | |
def start_switch (event): | |
log.debug("Controlling %s" % (event.connection,)) | |
Tutorial(event.connection) | |
core.openflow.addListenerByName("ConnectionUp", start_switch) |
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