Multi-VLAN Network Configuration with Open vSwitch and Mininet

This repository contains the implementation of a university-level networking project focused on VLAN segmentation, trunking, and inter-VLAN routing using two approaches:

1. Manual configuration using Linux Network Namespaces and Open vSwitch (OVS) CLI tools.
2. An automated, scalable setup using the Mininet network emulator and Python scripting.

Features

• VLAN Segmentation: Logical separation of hosts into isolated broadcast domains.
• Inter-VLAN Routing: Configuration of a virtual router to enable communication between VLANs.
• Open vSwitch Integration: Use of ovs-vsctl to configure access and trunk ports.
• Dynamic Topology Generation: A parameterized Python script to generate Mininet topologies based on user-defined VLANs and switch counts.
• Network Namespaces: Isolation of hosts and routers using Linux network namespaces to simulate real-world devices.

Repository Structure

.
├── openvswitch-setup/
│   ├── start.sh          # Script to build the manual network topology
│   └── remove_config.sh  # Script to clean up and reset the environment
│
└── mininet-topology/
    └── arbitrary_vlan_topology.py  # Python script for automated Mininet topology

Manual Setup Using Open vSwitch and Namespaces

This setup manually configures a network topology that includes:

• Three OVS bridges: br-access1, br-access2, and br-core

• Four hosts in different VLANs:

  • h1 and h2 in VLAN 10
  • h3 and h4 in VLAN 20

• One router namespace configured with sub-interfaces for inter-VLAN routing

IP Configuration

Host	VLAN	IP Address
h1	10	10.0.10.250/24
h2	10	10.0.10.251/24
h3	20	10.0.20.250/24
h4	20	10.0.20.251/24

Router interfaces:

• 10.0.10.1 (gateway for VLAN 10)
• 10.0.20.1 (gateway for VLAN 20)

Usage

cd openvswitch-setup
sudo ./start.sh        # Set up the network
sudo ip netns exec h1 ping 10.0.20.250   # Example connectivity test
sudo ./remove_config.sh   # Clean up configuration

Mininet-Based Dynamic VLAN Topology

This approach uses a Python script to programmatically create a VLAN-enabled network topology using Mininet and OVS.

Prerequisites

• Python 3
• Mininet

Script Features

• Customizable VLAN list
• Adjustable number of access switches
• Automatic assignment of VLAN-tagged ports and trunk ports
• Realistic emulation environment for testing

Usage

cd mininet-topology
sudo python arbitrary_vlan_topology.py

You will be presented with the Mininet CLI for interaction. Examples:

mininet> h10_1 ping h20_1      # Inter-VLAN communication
mininet> h10_1 ping h10_2      # Intra-VLAN communication
mininet> sh s0 ovs-vsctl show # Inspect switch configuration
mininet> exit                  # Exit and clean up

Customization

To modify the VLANs and number of switches:

def run():
    vlans = [10, 20, 50, 60]
    num_access_switches = 2
    ...

Concepts Covered

• Layer 2 Switching
• VLAN Tagging (802.1Q)
• Trunk and Access Ports
• Inter-VLAN Routing
• Linux Network Namespaces
• Software-Defined Networking with Open vSwitch
• Network Emulation with Mininet