Managing and Securing Computer Networks

Assignment 2

Full problem statement could be found at the Guy Leduc's website

Also this repo includes solution for Openflow Tutorial which is of_tutorial.py from mininet. The author's coding style is preserved.

Creating a topology

(in virtual machine as mininet)

$ cd ~/pox
$ mv $(mytree.py_from_your_location) mytree.py
$ mn --custom mytree.py --topo mytree,depth=2,fanout=3,hosts=4 --switch ovsk --mac --controller remote

Starting SDN Controller

$ cd ~/pox
$ mv $(mycontrol.py_from_your_location) mycontrol.py
$ ./pox.py log.level --DEBUG my_controller

Draft to compile a report

Major steps¹:

1. mytree.py

In fact, there are only few lines of code were changed: * Add __init__ (initializer) argument, save it as attribute * True/False variable is_core_switch = depth > 1 * for _ in range(fanout if is_core_switch else hosts): which means, if we deal with the core switch, fanout children are created else hosts children, that's exactly we had to do

2. Monitoring

Code obtained after Openflow tutorial (completed by ourselves as well) was used as a base to that task.

Periodic tasks scheduling was made using pox.lib.recoco.Timer object, as it recommended by the authors of POX.

send_stats_request procedure every 5 seconds sends port stats request to all switches. _handle_PortStatsReceived saves parsed response. log_stats every minute aggregates statistics prints it. However all of this covered in the code.

Unfortunately, we're not able to resolve host names or get tree topology inside Controller lifecycle, so implementation hardly depends on environment variables:

DEPTH
FANOUT
HOSTS They have the same meaning like in previous part.

3. Filtering

In order to check whether two MAC-addresses belongs to the same tenant, TenantMatched object is instantiates and passes to Controller. First of all it parses '/home/mininet/tenants.cfg' and assigns to every MAC-address from the same component unique number. After, when is_same_tenant method is fired, it checks if these addresses has the same component id.

In case when MAC is not presented in .cfg, it has id -1.

In case when one of given addresses is broadcast (ff:ff:ff:ff:ff:ff) method returns True.

Suggestions

To send requests at regular intervals, you will likely need to use python threads or timers.

I can imagine what other students might build using timers, especially if they're not familiar with python (There were lots at OpenFlow practice lesson). I advocate you to mention Timer, provided by POX developers. Usage is simple as follows:

# Execute func every 5 seconds
from pox.lib.recoco import Timer
Timer(5, func, recurring=True)

1. Follow commit history, to track step-by-step the way I've solved the task

neseleznev / ulg-mscn