Cisco Virtual Lab: DevNet Sandbox vs CML vs a Hosted Lab

A Cisco virtual lab is software that runs Cisco routers, switches and firewalls without the physical hardware, so you can configure, break and fix a network on your own schedule. Cisco itself offers three: Packet Tracer, DevNet Sandbox (which includes a free CML session) and Cisco Modeling Labs (CML) to run on your own machine. You can also host CML, EVE-NG or GNS3 yourself, or rent a hosted lab. They differ in what you can build, how long the lab lasts and whose hardware it runs on.

Table of contents

• Cisco virtual lab options at a glance
• Packet Tracer: the free simulator for CCNA
• DevNet Sandbox: free, but shared or time-limited
• CML on your own machine: CML-Free and Personal
• When to rent or host a lab instead
• Which Cisco virtual lab should you use?

Cisco virtual lab options at a glance

Start with the job, then pick the lab that fits it.

CloudMyLab sells the last two options, so keep that in mind as you compare. Hosted CML from CloudMyLab runs your CML license on our servers, and our Learning Labs cover ACI, SD-WAN, SD-Access and HyperFlex, with the ACI lab on physical Nexus 9000 switches. If one of Cisco's free options covers your job, start there.

Packet Tracer: the free simulator for CCNA

Packet Tracer is free from Cisco Networking Academy, and it is a simulator: it uses simplified models of networking protocols and Cisco IOS, and it does not run real IOS images. That keeps it light enough for any laptop, and it opens the .pkt lab files that many CCNA courses hand out.

The trade-off is fidelity. Some commands are missing and some behaviors differ from real devices, and when a lab misbehaves it can be hard to tell whether the problem is your configuration or the simulator. Once you move past CCNA topics, you need an emulator that runs real Cisco images. Our Packet Tracer alternatives guide covers that step.

DevNet Sandbox: free, but shared or time-limited

Cisco's DevNet Sandbox is free. Cisco says the DevNet team runs the sandboxes "at no cost", with "no license to buy, no subscription, and no Cisco support contract required". You need a Cisco.com account.

Always-On sandboxes are shared with other users and give you restricted admin access. Cisco's Sandbox FAQ warns that a change you make can affect everyone else on the same lab, so use them to read data and test API calls, and leave the network as you found it.

On-demand sandboxes are built for your reservation, private to you, and give you full admin access. They take longer to provision, and the session ends. Cisco's FAQ says each sandbox "has its own default session length and its own maximum. There is no global limit", so check the sandbox's detail page before you plan a lab around it.

DevNet also offers a CML sandbox. On its Cisco Modeling Labs page, Cisco says you can "sign up for a free 4-hour session with Cisco Modeling Labs", with a CML server and a sample topology already running. It is a good way to see CML before you install it, but a topology you build there does not survive the session.

Do not confuse the sandboxes with DevNet Learning Labs, which are step-by-step tutorials, or with Cisco dCloud, Cisco's demonstration platform. Whether you can schedule dCloud content depends on your Cisco account role, so check your access before you plan around it.

CML on your own machine: CML-Free and Personal

When you want a lab that stays where you left it, Cisco's answer is CML on your own hardware.

CML-Free "can run up to 5 nodes simultaneously", and unmanaged switches and external connectors do not count against that limit. Its image set includes IOL, IOL-L2 and ASAv, plus Linux host images. Linux nodes count toward the 5. The paid CML Personal ships with 20 Cisco nodes and Personal Plus with 40, and neither can expand. The CML license agreement permits all three for non-commercial use by a single named individual, including evaluation by an employee of a commercial entity. Our guide to what each CML tier includes goes into the differences, including CML Enterprise, the tier built for organizations with many users.

CML installs either on bare metal or as a virtual machine; as a VM it relies on nested virtualization for the nodes inside it. Cisco's system requirements treat Intel as the fully supported platform, AMD as best effort, and state that CML does not work on Apple Silicon (M series) Macs. Memory is usually the limit: a small IOL lab fits an ordinary Intel desktop, while heavier images such as Catalyst 8000V, which CML-Free does not include, use far more memory per node.

If you already own a capable Intel machine, CML Personal on it gives you a lab that persists with 20 or 40 nodes instead of 5. For a head-to-head with the open-source emulators, see GNS3 vs CML and EVE-NG vs CML.

When to rent or host a lab instead

Before you rent, two other routes exist: install CML on your own cloud server with nested virtualization or on bare metal, or buy CML Enterprise for a team. A hosted lab makes sense when the free options stop and you do not want to run the host yourself. The first case is a topology your machine cannot run: a CCNP or data center lab can outgrow a laptop quickly, and on an Apple Silicon Mac CML does not run at all. The second is a lab that has to persist, because a reservable sandbox or a 4-hour CML session ends while a hosted server keeps your topology between sessions.

Teams are the third case. CML Personal and Personal Plus are single-user licenses, so a team sharing one CML server needs a multi-user license such as CML-Enterprise. The last is real switches: Cisco's ACI Simulator uses simulated switches, so testing traffic through an ACI fabric needs physical hardware.

Licensing does not change when you host. Cisco licenses its CML reference images for use only within CML, so a hosted CML server still runs your own CML license, and a hosted EVE-NG or GNS3 server runs only the images you are separately licensed to use. CloudMyLab hosts CML without any affiliation with Cisco; CML licenses come from Cisco. A hosted lab also adds a subscription and some console latency, and it does not include other vendors' images you are not licensed for.

With CloudMyLab, hosted CML runs your CML license on our servers. Our guide to running CML as a hosted service explains how it works, and the free 24-hour trial covers hosted CML and hosted EVE-NG Pro.

Which Cisco virtual lab should you use?

If you are studying for CCNA and your course gives you .pkt files, use Packet Tracer. If you are learning Cisco APIs or automation, use DevNet Sandbox: Always-On to read and explore, a reservable sandbox when you need to change things. If you want real Cisco images in a lab that persists and you have a capable Intel machine, install CML-Free or CML Personal. If your machine cannot carry the topology, you use a Mac, or a team needs the same lab on a multi-user CML license, host CML or EVE-NG on someone else's servers. If an ACI design needs real switches, reserve a physical lab; our ACI lab guide shows what one includes.

If you are weighing CML against other emulators altogether, our guide to Cisco Modeling Labs alternatives covers when another platform fits better.

Frequently Asked Questions

What is a Cisco virtual lab?

A Cisco virtual lab is software that runs Cisco routers, switches and firewalls without the physical hardware. Packet Tracer simulates Cisco devices, while Cisco Modeling Labs, EVE-NG and GNS3 run real Cisco images. DevNet Sandbox and hosted labs give you ready-made environments on someone else's servers.

Is Cisco DevNet Sandbox free?

Yes. Cisco says the DevNet team runs the sandboxes at no cost, with no license, subscription or support contract required. You need a Cisco.com account. Always-On sandboxes are shared with other users, and reservable sandboxes are private but time-limited.

Is there a free Cisco virtual lab?

Yes, several. Packet Tracer is a free simulator, DevNet Sandbox is free, DevNet offers a free 4-hour CML session, and CML-Free runs up to 5 nodes on your own machine for non-commercial use.

Can I run Cisco Modeling Labs on a Mac?

Not on Apple Silicon. Cisco states that CML does not work on M series Macs, and it treats Intel as the fully supported platform and AMD as best effort. On a Mac, run CML on a separate Intel machine or a hosted server.

DevNet Sandbox vs CML: which should I use?

Use DevNet Sandbox to explore Cisco APIs and ready-made environments without installing anything. Use CML when you want to build your own topology with real Cisco images and keep it between sessions, either on your own Intel machine or on a hosted server.