I had a really busy fall this 12 months, 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 carried out to carry NetBox into my CML simulations in a simple and seamless vogue.
However at present, I’m again. And desperate to reveal two new contributions to the Cisco Modeling Labs (CML) neighborhood in your instant 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 venture, or one thing that includes creating a duplicate (or shut duplicate) 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. Nonetheless, 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 data and routinely 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 somewhat 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 Neighborhood 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’re welcome to vary these default credentials after you begin the node, however having an admin account and API entry accessible at node startup allows you to get began together with your community automation work instantly while not having to arrange NetBox your self.)
As well as, I’ve pre-populated a Producer known as “CML” together with Gadget Varieties for every of the CML node varieties 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 accelerates including gadgets to NetBox. Nonetheless, if 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 Gadget Varieties as wanted.
Whereas I labored to make utilizing the NetBox node as straightforward as potential, there are necessities for including it to a lab so it could possibly entry the CML lab particulars to populate NetBox. I’ve offered full particulars within the CML Neighborhood README for the node, and I encourage you to learn them if you arrange the brand new node by yourself CML server. I’ll cowl the highlights right here as nicely.
For starters, the NetBox node will want connectivity to the CML server’s REST API by an “exterior connector” node. It may be both a bridge or a NAT-based exterior connector; nonetheless, for a NAT-based connector, it is advisable 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 in 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 how one can use the node. You’ll discover non-compulsory blocks for customizing the server’s community configuration, however to routinely populate NetBox from CML, you’ll must uncomment and supply particulars for a set of setting 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 manner for the node to routinely “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 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 evaluate after the node finishes booting. Simply connect with the NetBox server’s console and evaluate 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 setting 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 Title: 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’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 gadgets... Including cables for 7 nodes from CML lab 'Instance NetBox Server Topology' to NetBox 📊 Processed cables for five/7 gadgets...
You would possibly surprise why you’ll wish to re-run the sync? For those who add extra nodes to the CML topology after it begins, or add hyperlinks between gadgets, these adjustments will likely be routinely added to NetBox. For those who’ve deleted nodes or cables, the script received’t clear these out; you’ll must delete them manually.
And you may additionally surprise what cml2netbox is? Effectively, 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 information in NetBox, however not in a NetBox occasion operating within the CML lab; slightly, 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 below the hood; it’s packaged instantly into the node/picture definition and routinely configured and run throughout node initialization. However now let’s take a look at how we are able to use the utility instantly.
Just 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 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 # 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 in 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 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 system varieties with NetBox system 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 system varieties for all node definitions with cml2netbox sync device-types. Nonetheless, this isn’t required. For those who run cml2netbox sync lab earlier than syncing the system varieties, the device will create system varieties for every node within the lab. It will take somewhat longer the primary time, as new device-types are created. However it does imply solely the required system varieties will likely be created.
However the actual enjoyable comes if 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 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 if 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 use a single NetBox server to carry information from 1, 10, and even 100 CML topologies!
And one final word… cml2netbox will create a .log file for every run of the device. By default, the logging degree is INFO, however when you run in “verbose” mode, you’ll get DEBUG degree logging within the file. This may be useful if/when one thing goes fallacious in a sync job, so you’ll be able to 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/?identify=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&identify=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 isn't 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 carried out!
Let it not be stated that Hank doesn’t preserve 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 simply make the most of one or each of the choices I shared.
In case you are new to CML, please try Introduction to Community Simulations with Cisco Modeling Labs | CMLLAB Studying Path in Cisco U. You can too get began with Cisco Modeling Labs – Free Version fast and straightforward.
Till subsequent time!
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