I had a really busy fall this yr, and now I can’t consider it’s been three months since my final weblog, “Bringing Some Supply of Fact to Your NetAI Agentic Playground.” That’s far longer than I had deliberate after I made my “public accountability assertion” about my subsequent weblog submit being in regards to the work I had performed to deliver NetBox into my CML simulations in a simple and seamless style.
However immediately, I’m again. And wanting to reveal two new contributions to the Cisco Modeling Labs (CML) neighborhood to your speedy use:
- A CML node and picture definition for a NetBox server
- CML2NetBox, a Python utility that auto-populates NetBox primarily based on a CML lab
Let’s dive into every of those choices and see how they work!
NetBox server node for Cisco Modeling Labs
Not each CML community I construct wants a NetBox server, however at any time when I’m engaged on a brand new community automation undertaking, or one thing that includes creating a reproduction (or shut duplicate) of our manufacturing community—a “digital cousin,” so to talk—I’ll need to have a supply of fact populated with knowledge from the community simulation.
Prior to now, I’ve manually populated NetBox with knowledge utilizing APIs, scripts, or CSV imports. Nevertheless, these choices aren’t nice, and so they weren’t a part of the lab itself. That’s the place this new node definition is available in.
Now I can merely drag the “NetBox” node into the topology and configure it to auto-populate from the CML lab definition itself.
After that, simply begin the lab, and the node will learn the CML lab info and robotically create websites, gadgets, IP addresses, and even cables connecting interfaces throughout all nodes within the topology.
Fairly neat, proper? For these of you curious about some technical particulars, let’s dive in a bit of deeper.
First up, the node definition, or extra precisely, the picture definition that has been constructed and shared, relies on the Alpine 3.21 picture included on the CML 2.9 reference platform. The NetBox-Docker undertaking was then used to deploy NetBox Group v4.4.5.
This NetBox server is meant to run inside CML as a part of lab topologies, and I wished it to be very simple to make use of in these labs. So I made some “opinionated” decisions in its configuration.
To align with different default credentials for nodes inside CML, the admin person for NetBox has been pre-created with a username and password of cisco.
I additionally created an API token “0123456789012345678901234567890123456789” for this person. (You’re welcome to vary these default credentials after you begin the node, however having an admin account and API entry out there at node startup allows you to get began together with your community automation work instantly with no need to arrange NetBox your self.)
As well as, I’ve pre-populated a Producer referred to as “CML” together with System Sorts for every of the CML node varieties within the reference platform, in addition to a number of further node definitions from the cml-community and my private use. Having them pre-created quickens including gadgets to NetBox. Nevertheless, when you’ve got a node definition that’s NOT included within the base picture, don’t fear. The code that populates NetBox will dynamically create new System Sorts as wanted.
Whereas I labored to make utilizing the NetBox node as simple as doable, there are necessities for including it to a lab so it might entry the CML lab particulars to populate NetBox. I’ve offered full particulars within the CML Group README for the node, and I encourage you to learn them whenever you arrange the brand new node by yourself CML server. I’ll cowl the highlights right here as properly.
For starters, the NetBox node will want connectivity to the CML server’s REST API by way of an “exterior connector” node. It may be both a bridge or a NAT-based exterior connector; nevertheless, for a NAT-based connector, you might want to replace a firewall rule within the CML Cockpit interface first. Full particulars on the change required and why are documented within the README.
Subsequent, you’ll must replace the default CONFIG for the node with particulars to your CML server and the lab you need to synchronize with. The default day 0 config supplied with the node contains detailed feedback I left to assist customers perceive the choices and how you can use the node. You’ll discover non-compulsory blocks for customizing the server’s community configuration, however to robotically populate NetBox from CML, you’ll must uncomment and supply particulars for a set of surroundings variables.
# export VIRL2_URL=https://192.168.255.1 # export VIRL2_USER=admin # export VIRL2_PASS=1234QWer # export VIRL2_VERIFY_SSL=False # export LAB_NAME="My CML Lab"
These values are wanted as a result of, whereas the NetBox server runs on the CML server, there is no such thing as a method for the node to robotically “know” these particulars in regards to the server. So we offer them as ENVs so the scripts that connect with CML know the handle, credentials, and which lab on the CML server to synchronize with. I count on that you just’ll synchronize the identical lab that the NetBox node is working on, however you don’t must. You may synchronize any lab from the CML server.
Talking of scripts, you’ll see references to 2 scripts on the finish of the configuration. These scripts first guarantee NetBox is up and working, then connect with and sync from CML. The output from each of those scripts is saved on the node in two log recordsdata that you could evaluation after the node finishes booting. Simply connect with the NetBox server’s console and evaluation the contents of the recordsdata.
((.venv) ) netbox-server:~$ cat startup_log.txt Checking if NetBox (http://localhost) is responding... Website not responding, ready 5 seconds... (try 1/48) . Website not responding, ready 5 seconds... (try 14/48) Website is responding! (try 15) Checking if CML Controller (https://192.168.255.1) is reachable... Website is responding! (try 1) Writing VIRL2 surroundings variables to /residence/cisco/.profile... Making an attempt to sync topology to NetBox... 🔄 Beginning lab topology synchronization... 📡 CML Server: https://192.168.255.1 🗄️ NetBox Server: http://localhost 🧪 Lab Identify: Instance NetBox Server Topology Starting lab synchronization now. Including 6 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed 5/6 gadgets... Including cables for six nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed cables for five/6 gadgets... Topology synced efficiently.
While you’re on the console, you may re-run the sync like this.
((.venv) ) netbox-server:~$ cml2netbox sync lab 🔄 Beginning lab topology synchronization... 📡 CML Server: https://192.168.255.1 🗄️ NetBox Server: http://localhost 🧪 Lab Identify: Instance NetBox Server Topology Starting lab synchronization now. Including 7 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed 5/7 gadgets... Including cables for 7 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed cables for five/7 gadgets...
You would possibly marvel why you’d need to re-run the sync? Should you add extra nodes to the CML topology after it begins, or add hyperlinks between gadgets, these modifications shall be robotically added to NetBox. Should you’ve deleted nodes or cables, the script gained’t clear these out; you’ll must delete them manually.
And you may additionally marvel what cml2netbox is? Nicely, that’s the underlying “magic” that makes this node work. And it’s the topic we’re going to speak about subsequent!
CML2NetBox: A Python utility for EVERYONE!
I notice that a few of you may want your CML lab knowledge in NetBox, however not in a NetBox occasion working within the CML lab; quite, in a NetBox server you have already got working. If that sounds such as you, then don’t fret, simply pip set up cml2netbox and have enjoyable!
The reality is that the NetBox server node makes use of cml2netbox below the hood; it’s packaged instantly into the node/picture definition and robotically configured and run throughout node initialization. However now let’s have a look at how we are able to use the utility instantly.
Much like the node configuration, you’ll want to supply values for the CML server you’ll be synchronizing from, and additionally, you will must configure the small print for the NetBox server you’ll be synchronizing to. An instance .env file is supplied with the code on GitHub.
# CML2NetBox Configuration Instance # Copy this file to .env and fill in your values # CML Lab Particulars LAB_NAME="Your CML Lab" LAB_ID="your-lab-id-uuid-if-needed" # CML Server Configuration # Can even use VIRL2_* variants for backward compatibility CML2_URL=https://your-cml-server.instance.com CML2_USER=your-username CML2_PASS=your-password CML2_VERIFY_SSL=True # NetBox Server Configuration NETBOX_URL=https://your-netbox-server.instance.com NETBOX_API_TOKEN=your-api-token-here NETBOX_VERIFY_SSL=True
Simply copy this file and supply the info to your personal servers.
For completeness’ sake, you may as well present all this knowledge as command-line choices when working cml2netbox, however I discover setting them in a file is less complicated than typing them each time I run the command.
Let’s see what choices exist for the device.
cml2netbox sync --help Utilization: cml2netbox sync [OPTIONS] COMMAND [ARGS]... Synchronization instructions for CML and NetBox integration. Choices: --help Present this message and exit. Instructions: device-types Sync CML gadget varieties with NetBox gadget varieties. lab Sync CML lab topology with NetBox.
There are two choices. Good.
You’ll be able to “put together” a NetBox server by creating the CML producer and gadget varieties for all node definitions with cml2netbox sync device-types. Nevertheless, this isn’t required. Should you run cml2netbox sync lab earlier than syncing the gadget varieties, the device will create gadget varieties for every node within the lab. This may take a bit of longer the primary time, as new device-types are created. But it surely does imply solely the required gadget varieties shall be created.
However the actual enjoyable comes whenever you sync a lab like this.
cml2netbox sync lab 🔄 Beginning lab topology synchronization... 📡 CML Server: https://100.75.36.232 🗄️ NetBox Server: http://100.75.36.232:6999 🧪 Lab Identify: CCNA Prep 2025 S3E3 Superior ACL Exploration Starting lab synchronization now. Including 8 nodes from CML lab 'CCNA Prep 2025 S3E3 Superior ACL Exploration' to NetBox 📊 Processed 5/8 gadgets... Including cables for 8 nodes from CML lab 'CCNA Prep 2025 S3E3 Superior ACL Exploration' to NetBox
On this instance, I synchronized a 2nd CML lab from the topology above into the NetBox server to display what occurs whenever you sync a number of CML labs into the identical NetBox server and the way they’re differentiated.
CML2NetBox will create a brand new NetBox Website for every CML lab synchronized. Which means you should utilize a single NetBox server to carry knowledge from 1, 10, and even 100 CML topologies!
And one final be aware… cml2netbox will create a .log file for every run of the device. By default, the logging stage is INFO, however if you happen to run in “verbose” mode, you’ll get DEBUG stage logging within the file. This may be useful if/when one thing goes improper in a sync job, so you may determine what occurred. In my testing, this most frequently occurs when you may have a number of labs on a single NetBox server and encounter duplicate or conflicting objects.
cml2netbox -v sync lab tail -n 10 ./20251202-140246-cml2netbox.log 2025-12-02 14:03:13 - httpcore.http11 - DEBUG - response_closed.began 2025-12-02 14:03:13 - httpcore.http11 - DEBUG - response_closed.full 2025-12-02 14:03:13 - urllib3.connectionpool - DEBUG - http://100.75.36.232:6999 "GET /api/dcim/gadgets/?title=server-sw&site_id=2&restrict=0 HTTP/1.1" 200 1924 2025-12-02 14:03:13 - urllib3.connectionpool - DEBUG - http://100.75.36.232:6999 "GET /api/dcim/interfaces/?device_id=14&title=port0&restrict=0 HTTP/1.1" 200 2333 2025-12-02 14:03:13 - cml2netbox_pkg.netbox_helpers - INFO - Interface port0 already has a cable: 11 2025-12-02 14:03:13 - cml2netbox_pkg.netbox_helpers - INFO - No cables created for node server-sw 2025-12-02 14:03:13 - cml2netbox_pkg.netbox_helpers - INFO - Connecting cables for CML node setup-installation 2025-12-02 14:03:13 - cml2netbox_pkg.netbox_helpers - DEBUG - Skipping hyperlink the place present node is just not interface_a 2025-12-02 14:03:13 - cml2netbox_pkg.netbox_helpers - INFO - No cables created for node setup-installation 2025-12-02 14:03:13 - cml2netbox_pkg.cli - INFO - Accomplished synchronization of 8 nodes to NetBox
And performed!
Let it not be stated that Hank doesn’t maintain his guarantees… it simply would possibly take me 3 months to get to it 😉
Anyway, I hope you loved this weblog submit, and much more so, that you just benefit from one or each of the choices I shared.
In case you are new to CML, please take a look at Introduction to Community Simulations with Cisco Modeling Labs | CMLLAB Studying Path in Cisco U. You may as well get began with Cisco Modeling Labs – Free Version fast and straightforward.
Till subsequent time!
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