Ryu controller - deal with openflow packets notes

- Controller receives a  packet from a switch if the switch failed to look up it's flow table
- Get incoming packet message, src mac/ip, dst mac/ip, ofproto, ... whatever you want
- Learn a switch-port-mac_address entry

Packets received in Ryu controller

- Use ryu as remote controller to listen packet_in event which is usually triggered when a open virtual switch failed to look up an legal entry in the flow table.
- Here are some packet examples sending from ovs:

Disable ipv6

- When starting mininet with arbitrary topology by using ryu as a remote controller, there are plenty of packets sends from each hosts to a set of strange mac addresses start with 33:33:XX:XX...

- I didn't send these pkts (they started sending immediately after mininet network was set up), and I didn't want they show up. These irritating messages kept refreshing the controller console and led to debug trouble.

Ryu -- Mininet Sample: k=4 Fat Tree

- Start Ryu manager (optional:with GUI needed files)

ryu-manager --verbose --observe-links ryu.app.simple_switch ryu.app.rest_topology  ryu.app.ofctl_rest ryu.topology.switches

Ryu - Installation

- Ryu is a SDN controller platform which supports OpenFlow. See also: http://osrg.github.io/ryu/

- By https://github.com/mininet/openflow-tutorial/wiki/Create-a-Learning-Switch#Controller_Choice_Ryu_Python, python-gevent, python-routes, python-webob, and python-paramiko should be installed.

Mininet - FatTree Topology

- Fat tree topology: https://en.wikipedia.org/wiki/Fat_tree

- If there is a loop in the topology, the hosts cannot ping the others because https://github.com/mininet/mininet/wiki/FAQ#ethernet-loops

Mininet OpenFlow Tutorial - Learn Development Tools

https://github.com/mininet/openflow-tutorial/wiki

- Start with a topology with 3 hosts and 1 switch (and 1 controller)

• "sudo mn --topo single,3 --mac --switch ovsk --controller remote"
• --switch ovsk: Open vSwitch 
• --mac: set the MAC address to hosts' IP address