When I was writing a blog post, I needed a link to the netlab lab topology documentation, so I searched for “netlab lab topology” (I know I’m lazy, but it felt quicker than navigating the sidebar menu).

The AI overview I got was way too verbose, but it nailed the Key Concepts and How It Works well enough that I could just use them in the netlab README.md file. Maybe this AI thing is becoming useful after all ;)

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You’ll probably get a different AI overview with every search. This is the one I got together with my search results

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A netlab lab topology is a YAML-defined description of a virtual network lab, outlining devices, links, and configurations, designed for use with Infrastructure-as-Code principles. You define the high-level network structure in YAML, and netlab then generates the necessary files for various virtualization platforms (like KVM, Docker), container networking tools (Containerlab), and automation frameworks (Ansible). 

Key Concepts

• YAML Topologies:  The core of a netlab topology is a YAML file that acts as the blueprint for your lab. 
• Infrastructure-as-Code (IaC):  netlab promotes using code (YAML) to define and manage network labs, moving away from manual, GUI-based methods. 
• Abstraction:  You describe the logical network structure without getting bogged down in the specifics of the underlying virtualization platform. 
• Virtualization Providers:  netlab supports deploying labs on different platforms, including KVM/libvirt, Docker containers, or even physical devices. 
• Components:  For large or recurring structures (like a leaf-and-spine fabric), you can define reusable components that can be included multiple times within a single topology. 
• Validation:  netlab provides a framework to validate attributes of topology elements and configuration modules, ensuring accuracy. 
• Generation:  Based on the YAML topology, netlab can generate configuration files for tools like Containerlab, Vagrant, and Ansible inventory files for automation. 

How it Works 

1. Define the Topology: You create a YAML file to describe your desired network, including devices, their connections (links), and initial configurations like VLANs or routing protocols.
2. Use netlab Commands: You use netlab CLI commands to process your YAML topology.
3. Generate Outputs: netlab creates the necessary configuration files for your chosen virtualization platform or container networking tool.
4. Deploy the Lab: You use the generated files to launch your virtual network lab.

Benefits 

• Repeatability: Easily reproduce the same lab environment multiple times.
• Flexibility: Use the same YAML topology with different virtualization providers.
• Automation: Generate configurations and inventories for automated deployments and management.
• Scalability: Create complex, structured topologies with reusable components.