Create The Network Topology Write A Python Script To Create

Create The Network Topologywrite A Python Script To Create

Create the network topology, implement flow rule pushing on switches, measure bandwidth, and count packet loss for specific flows based on given topology and constraints.

Paper For Above instruction

The assignment involves constructing a network topology, deploying a controller to manage flow rules, measuring link bandwidth, and estimating packet loss for specific traffic flows within a simulated network environment. This comprehensive task entails multiple stages, from setting up the topology using a Python script to implementing intelligent flow management policies and conducting performance measurements.

1. Network Topology Creation (prob1.py)

The first step in this project is to model the network topology visually represented in Figure 1. Although the figure is only referenced here, the description suggests a topology consisting of four hosts (H1, H2, H3, H4) and four switches (S1, S2, S3, S4) arranged in a particular configuration. For simulation purposes, tools like Mininet, which allow swift creation of network topologies through Python scripts, are ideal.

In the script, each host and switch is instantiated, and links are established between them, with specific link parameters such as bandwidth, delay, and packet loss rate. These parameters are customizable but should be set to reflect realistic network conditions. Port numbers are assigned to switch interfaces systematically; for example, following a convention like starting from 1 and incrementing for each link, which ensures clarity when configuring flow rules.

2. Push the Flow Rules (prob2.py)

The second component involves creating a controller script that pushes flow rules onto switches to enforce specific traffic constraints:

- Block all traffic between H3 and H1.

- Route HTTP traffic (typically identified by TCP port 80) between H4 and H1 via Switch S2, and all other traffic between these hosts via Switch S3.

- Route traffic between H3 and H2 through Switch S3.

- Ensure all remaining traffic follows the shortest available path.

Implementing these rules requires analyzing the network topology to determine shortest paths, which can be achieved using algorithms like Dijkstra’s. The controller sends OpenFlow flow modification messages to the switches to forward or drop packets based on source/destination IPs, MAC addresses, ports, or protocol types.

3. Link Bandwidth Measurement (prob3.py)

The third script measures the instantaneous bandwidth on links connected to Switch S2 after flow rules are enforced. This can be done by generating test traffic on these links—using tools like iperf, or generating traffic with Scapy or custom scripts—and measuring throughput over a specified interval. The controller script facilitates this process, coordinating traffic generation and data collection, finally calculating and displaying current bandwidth utilization.

4. Packet Loss Count for Specific Traffic Flows (prob4.py)

Finally, the packet loss count for HTTP and non-HTTP flows between H4 and H1, passing through specific switches, is measured. This involves injecting traffic flows for the specified paths and monitoring at the endpoints and intermediate switches to count sent and received packets, thereby calculating losses. This can be achieved with packet capture tools like tcpdump or Wireshark, or programmatically by analyzing flow statistics provided by OpenFlow.

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Implementation Outline

- Topology setup: Use Mininet API in Python to instantiate hosts, switches, and links with specified parameters.

- Flow rule management: Utilize the Ryu controller framework or POX controller for pushing flow rules, employing shortest path calculations and policy enforcement.

- Performance metrics: Integrate iperf or similar tools within scripts to generate and measure throughput.

- Packet loss measurement: Capture traffic statistics periodically or during test runs to record packet drops or missed packets.

Conclusion

This project demonstrates a comprehensive approach to software-defined networking, integrating topology design, traffic engineering through flow rules, and performance measurement. Mastery of tools like Mininet, OpenFlow, and control plane programming is essential. Proper implementation ensures controlled, efficient, and measurable network behavior aligned with specified constraints.

References

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  • Mininet: An Instant Virtual Network on Your Laptop (2014). https://github.com/mininet/mininet
  • Ryu SDN Framework. https://osrg.github.io/ryu/
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