I had a really busy fall this yr, and now I can’t imagine 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 concerning the work I had finished to carry NetBox into my CML simulations in a straightforward and seamless vogue.
However in the present day, I’m again. And desperate to reveal two new contributions to the Cisco Modeling Labs (CML) group on your quick use:
- A CML node and picture definition for a NetBox server
- CML2NetBox, a Python utility that auto-populates NetBox based mostly 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 venture, or one thing that includes creating a duplicate (or shut reproduction) of our manufacturing community—a “digital cousin,” so to talk—I’ll wish to have a supply of fact populated with information from the community simulation.
Previously, I’ve manually populated NetBox with information utilizing APIs, scripts, or CSV imports. Nevertheless, these choices aren’t nice, they usually 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 mechanically create websites, units, IP addresses, and even cables connecting interfaces throughout all nodes within the topology.
Fairly neat, proper? For these of you interested by some technical particulars, let’s dive in a bit deeper.
First up, the node definition, or extra precisely, the picture definition that has been constructed and shared, is predicated on the Alpine 3.21 picture included on the CML 2.9 reference platform. The NetBox-Docker venture 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 needed it to be very straightforward to make use of in these labs. So I made some “opinionated” selections in its configuration.
To align with different default credentials for nodes inside CML, the admin consumer for NetBox has been pre-created with a username and password of cisco.
I additionally created an API token “0123456789012345678901234567890123456789” for this consumer. (You might be welcome to vary these default credentials after you begin the node, however having an admin account and API entry out there at node startup helps you to get began along with your community automation work instantly while not having to arrange NetBox your self.)
As well as, I’ve pre-populated a Producer referred to as “CML” together with System Varieties for every of the CML node sorts within the reference platform, in addition to a number of extra node definitions from the cml-community and my private use. Having them pre-created hastens including units to NetBox. Nevertheless, in case you have a node definition that’s NOT included within the base picture, don’t fear. The code that populates NetBox will dynamically create new System Varieties as wanted.
Whereas I labored to make utilizing the NetBox node as straightforward as doable, there are necessities for including it to a lab so it may possibly 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 once 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 means of an “exterior connector” node. It may be both a bridge or a NAT-based exterior connector; nonetheless, for a NAT-based connector, it’s good 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 have to replace the default CONFIG for the node with particulars on your CML server and the lab you wish to synchronize with. The default day 0 config supplied with the node contains detailed feedback I left to assist customers perceive the choices and the best way to use the node. You’ll discover non-compulsory blocks for customizing the server’s community configuration, however to mechanically populate NetBox from CML, you’ll have to uncomment and supply particulars for a set of atmosphere 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 isn’t a manner for the node to mechanically “know” these particulars concerning the server. So we offer them as ENVs so the scripts that connect with CML know the deal with, credentials, and which lab on the CML server to synchronize with. I anticipate that you simply’ll synchronize the identical lab that the NetBox node is operating on, however you don’t must. You possibly can 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 operating, then connect with and sync from CML. The output from each of those scripts is saved on the node in two log recordsdata 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 atmosphere variables to /residence/cisco/.profile... Trying to sync topology to NetBox... 🔄 Beginning lab topology synchronization... 📡 CML Server: https://192.168.255.1 🗄️ NetBox Server: http://localhost 🧪 Lab Title: Instance NetBox Server Topology Starting lab synchronization now. Including 6 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed 5/6 units... Including cables for six nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed cables for five/6 units... Topology synced efficiently.
When you are on the console, you’ll be able to 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 Title: Instance NetBox Server Topology Starting lab synchronization now. Including 7 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed 5/7 units... Including cables for 7 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed cables for five/7 units...
You may marvel why you’ll wish to re-run the sync? Should you add extra nodes to the CML topology after it begins, or add hyperlinks between units, these modifications will probably be mechanically added to NetBox. Should you’ve deleted nodes or cables, the script gained’t clear these out; you’ll have to delete them manually.
And you may also marvel what cml2netbox is? Properly, 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 understand that a few of you may want your CML lab information in NetBox, however not in a NetBox occasion operating within the CML lab; reasonably, in a NetBox server you have already got operating. 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 beneath the hood; it’s packaged straight into the node/picture definition and mechanically configured and run throughout node initialization. However now let’s take a look at how we will use the utility straight.
Much like the node configuration, you’ll want to supply values for the CML server you’ll be synchronizing from, and additionally, you will have to configure the main points 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 # May 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 on your personal servers.
For completeness’ sake, you too can present all this information as command-line choices when operating cml2netbox, however I discover setting them in a file is easier 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 system sorts with NetBox system sorts. lab Sync CML lab topology with NetBox.
There are two choices. Good.
You possibly can “put together” a NetBox server by creating the CML producer and system sorts for all node definitions with cml2netbox sync device-types. Nevertheless, this isn’t required. Should you run cml2netbox sync lab earlier than syncing the system sorts, the device will create system sorts for every node within the lab. This may take a bit longer the primary time, as new device-types are created. However it does imply solely the required system sorts will probably be created.
However the actual enjoyable comes once 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 Title: 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 units... 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 once 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. Because of this you should use a single NetBox server to carry information from 1, 10, and even 100 CML topologies!
And one final observe… cml2netbox will create a .log file for every run of the device. By default, the logging degree is INFO, however in case you run in “verbose” mode, you’ll get DEBUG degree logging within the file. This may be useful if/when one thing goes flawed in a sync job, so you’ll be able to determine what occurred. In my testing, this most frequently occurs when you might 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/units/?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 will not be 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 finished!
Let it not be stated that Hank doesn’t hold his guarantees… it simply may take me 3 months to get to it 😉
Anyway, I hope you loved this weblog submit, and much more so, that you simply make the most of one or each of the choices I shared.
If you’re new to CML, please try Introduction to Community Simulations with Cisco Modeling Labs | CMLLAB Studying Path in Cisco U. It’s also possible to get began with Cisco Modeling Labs – Free Version fast and simple.
Till subsequent time!
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