Programming Assignment Solutions for Coursera SDN Course

Below are assignment descriptions from Nick Feamster's SDN Coursera

1. CustomTopo.py Data center networks typically have a tree-like topology. End-hosts connect to top-of-rack switches, which form the leaves (edges) of the tree; one or more core switches form the root; and one or more layers of aggregation switches form the middle of the tree. In a basic tree topology, each switch (except the core switch) has a single parent switch.
   Additional switches and links may be added to construct more complex tree topologies (e.g., fat tree) in an effort to improve fault tolerance or increase inter-rack bandwidth.

In this assignment, your task is to create a simple tree topology. You will assume each level i.e., core, aggregation, edge and host to be composed of a single layer of switches/hosts with a configurable fanout value (k).

2. firewall.py , firewall-policies.csv A Firewall is a network security system that is used to control the flow of ingress and egress traffic usually between a more secure local-area network (LAN) and a less secure wide-area network (WAN). The system analyses data packets for parameters like L2/L3 headers (i.e., MAC and IP address) or performs deep packet inspection (DPI) for higher layer parameters (like application type and services etc) to filter network traffic. A firewall acts as a barricade between a trusted, secure internal network and another network (e.g. the Internet) which is supposed to be not very secure or trusted.

In this assignment, your task is to implement a layer 2 firewall that runs alongside the MAC learning module on the POX OpenFlow controller. The firewall application is provided with a list of MAC address pairs i.e., access control list (ACLs). When a connection establishes between the controller and the switch, the application installs flow rule entries in the OpenFlow table to disable all communication between each MAC pair.

3. topologySlice.py, mininetSlice.py, videoSlice.py The first part of the assignment should give you a basic understanding of how to "slice" a network using a SDN controller. The goal of this part is to divide the network into two separate slices: upper and lower, as shown below. Users in different slices should not be able to communicate with each other. In practice, a provider may want to subdivide the network in this fashion to support multi-tenancy (and, in fact, the first part of this assignment provides similar functionality as ordinary VLANs).

In the previous part of the assignment, you learned how to slice a network based on the network's physical topology. It is also possible to slice the network in more interesting ways, such as based on the application that is sending the traffic. SDN networks in principle can be sliced on any attributes of flowspace.

Recall that the topology has two paths connecting two sites: a high-bandwidth path and a low-bandwidth path. Suppose that you want to prioritize video traffic in our network by sending all the video traffic over the high bandwidth path, and sending all the other traffic over the default low bandwidth path. File transfers won't be affected by the video traffic, and vice versa. In this part of the assignment, you'll use network slicing to implement this isolation.