How to build an SD-WAN lab in Cisco Modeling Labs 2 (CML2) 

What You Will Learn how to build sd-wan in cml2

• What CML2 is and why it supports SD-WAN labs
• Prerequisites and IDEA for your SD-WAN lab
• Step-by-step IN proses to build a basic SD-WAN fabric in CML2
• Configuration tips, automation secrets
• Common pitfalls and troubleshooting
• Summary and next step

1. Understanding CML2 and SD-WAN Compatibility

Cisco Modeling Labs 2 (CML2) is a network simulation emulation platform from Cisco that lets you model, deploy and test network topologies virtually. According to release notes, CML2 (v2.7 and later) supports Catalyst SD-WAN images (virtual SD-WAN Manage Controller Edge as part of its offering. Cisco DevNet+2Cisco DevNet+2

2. Preparation ANDPrerequisites how to build sd-wan in cml2

Before you start building your SD-WAN fabric in CML2, you should plan the following:

Hardware/Resources & Licensing

• Ensure your host machine or VM runs CML2 with sufficient CPU, RAM, storage. SD-WAN Manager / Controller images can be resource-intensive. See community feedback for issues such as low resources causing instability. Reddit+1
• A proper CML2 license that supports SD-WAN images and features. CML2 release notes indicate that SD-WAN support became available with the proper image definitions. Cisco DevNet

Software/Images

• Obtain the correct SD-WAN virtual images (Manager, Controller, Validator, Edge). CML2 must have node definitions that map to these images. Cisco DevNet+1

• Make sure to specify underlay transports (Internet, MPLS) if you plan to simulate realistic WAN links.

Topology & Design

• Decide on the number of sites/edges you want (for example: one hub site with Manager + Controller + Validator, plus two branch sites with Edge routers).
• Map underlay networks: maybe “INET” for Internet transport, “MPLS” for MPLS transport, and “VPN0” for overlay. The SD-WAN Lab Deployment Tool uses these names in examples. GitHub+1
• Plan IP addressing and connectivity (e.g., different subnets for INET vs MPLS vs overlay).
• Consider automation early if you plan many nodes (see section 4).

Documentation & how to build an SD-WAN lab in Cisco Modeling Labs 2

how to build sd-wan in cml2

• For real SD-WAN fabrics you often need certificates and licenses (e.g., vEdge registration file) so that your edge devices can onboard to the Manager. Even in lab mode, you should simulate these steps or use the tools provided. Cisco DevNet+1

3. Step-by-Step: Building the SD-WAN Lab in CML2

Below is a structured walkthrough for a basic SD-WAN fabric in CML2.

Step 1: Prepare CML2

• Upload the SD-WAN virtual images into the CserverML2  (Manager, Controller, Edge images). Ensure node definitions are created so you can select them when building topology.

Step 2: Build the Topology 

• In the CML2 GUI, create a new lab.
• Add nodes:
  • Manager (SD-WAN Manager / vManage) node
  • Controller(s) (vSmart/vBond or equivalent)
  • Validator node (if required)
  • Edge routers (branch or hub edges)
• Add links that represent underlay networks: for example, one link for “Internet” transport, another for “MPLS” =. Use subnets like 172.16.1.0/24 for INET, 172.16.2.0/24 for MPLS (that aligns with example tool usage) GitHub+1
• Connect the nodes accordingly: edges connect to both INET and MPLS networks to simulate dual-transport WAN, and to overlay tunnel network if needed.

Step 3: Boot Nodes & Initial Configuration and

how to build an SD-WAN lab in Cisco Modeling Labs 2

how to build sd-wan in cml2

• Start the nodes in CML2.
• On the Manager node, access its console and configure basic settings: hostname, IP addressing on the management/overlay network.
• On Edge nodes, configure underlay interfaces (Internet interface, MPLS interface) so they can reach the Manager and Controller nodes.
• If you’ve downloaded registration files (e.g., serialFile.viptela or equivalent), upload them into the Manager for edge device onboarding. Cisco DevNet+1

Step 4: Certificate & Overlay Setup how to build sd-wan in cml2

• Generate or import certificates for the SD-WAN fabric (Manager, Controllers, Edge). Ensure they trust each other. In lab mode you may use self-signed or test certs. The tool automates some parts. Cisco+1
• On the Manager or Controller, set up feature templates (e.g., interface templates, VPN templates) and apply them to device groups (e.g., branch edges vs hub edges).
• Define overlay VPNs (e.g., VPN0 or VPN10) for internal data plane connectivity.

Step 5: Onboarding Edge Devices

• On each Edge node, ensure the underlay connectivity is active (ping the Manager).
• From the Manager GUI, you should see the Edge device as “discovered” or “claimed” (depending on your version). Approve and associate templates.
• Once onboarded, the Edge will build TLOCs (transport locators) and participate in the SD-WAN overlay.

Step 6: Validate Connectivity

• From Edge to Edge (or Edge to Hub) ping across the overlay VPN to ensure site-to-site connectivity.
• On Manager/Controller GUI, verify overlay status, TLOCs, edge status.

 

Stage 7: Enlarge & Mechanize

• Once the core is built, you can add more branch edges or controllers. The SD-WAN Lab Deployment Tool supports adding nodes automatically. GitHub+1
• Use automation (Python/Ansible) or the tool (sdwan-lab deploy / sdwan-lab add) to scale up. Example: sdwan-lab add 3 edge 21.4.1 would add 3 edge nodes.

4. Using the SD-WAN Lab Deployment Tool (Automation)

If you want to streamline building your SD-WAN fabric in CML2, the open-source Catalyst SD‑WAN Lab Deployment Tool supports this. PyPI+1

Install & Prepare & how to build sd-wan in cml2

how to build sd-wan in cml2

• On a Linux or macOS host (or Windows via WSL):

• python3 -m venv venv
• source venv/bin/activate
• pip install –upgrade catalyst-sdwan-lab
• sdwan-lab –version

PyPI+1

• Ensure CML2 version is at least 2.6 (tool requirement) and SD-WAN images and node definitions are uploaded. PyPI+1

Typical Workflow

how to build an SD-WAN lab in Cisco Modeling Labs 2

• Setup task: define node types, upload images, clean old definitions. GitHub+1
• Deploy task: create a base SD-WAN fabric with underlay networks and core nodes (Manager, Controller, Validator, gateway). Cisco
• Add task: add more nodes (edges/controllers) into existing topology. GitHub
• Backup task: snapshot topology and configurations for reuse.

Benefits AND Limits and how to build sd-wan in cml2

• Benefits: saves time (minutes vs hours) to deploy a full fabric. Cisco+1

5. Best Practices AND Troubleshooting Instructions

Best Performs AND how to build sd-wan in cml2

• Assign adequate resources (especially CPU/RAM/disk) to Manager and Controller nodes. Some users have reported startup problems with insufficient resources. Reddit
• Clearly separate underlay transport networks (Internet vs MPLS) in your lab design.
• Use descriptive naming (Hub-Edge1, Branch-Edge2) to keep topology clarity.
• Regularly snapshot your CML2 lab state so you can restore if something breaks.

Shared Issues AND how to build sd-wan in cml2

• Manager GUI not accessible: Ensure you assigned proper IP to overlay/management interface and permit NAT/bridge connectivity. Cisco Community
• Edge fails to onboard: Check that node has reachability to Manager over underlay, and that its registration file/certificate is correct.
• Resource constraints: Manager may hang or crash if memory/CPU/disk is low — increase resources, check logs.
• Image compatibility: Make sure images uploaded into CML2 match the node definitions and SD-WAN version you intend to run.
• Overlay tunnels down: Verify underlay (TLOC) connectivity, controller discovery, and policy/config templates are correctly applied.

6. Next Steps and how to build sd-wan in cml

• Implement advanced features: application-aware routing, service chaining, security integration (firewall, cloud secure edge).
• Integrate with orchestration/automation: Using Ansible or Python to manage device templates, policies, adding branches dynamically.
• Scale the topology: many branch edges, full dual-hub architecture, multi-cloud connectivity.

How to Build SD-WAN in CML2: A Complete Step-by-Step Guide

Building SD-WAN in CML2 (Cisco Modeling Labs 2) is one of the best ways to learn, test, and simulate a software-defined WAN environment before deploying it in production. In this guide, you’ll learn exactly how to build SD-WAN in CML2, from setting up the lab to configuring controllers, edge devices, and policies. Whether you’re a student, network engineer, or IT enthusiast, this article will walk you through every step in a clear, user-friendly way.