EVE-NG vs Cisco CML: Which Network Emulator Should You Use?
Both EVE-NG and Cisco Modeling Labs (CML) put real network operating systems on your screen instead of the simplified approximation you get from Packet Tracer — you run the actual IOS, IOS XE, or NX-OS control plane, so the CLI, timers, and protocol behavior match hardware. The choice between them is not really about which one "emulates better"; both run genuine vendor images under a hypervisor, and a correctly built OSPF or spanning-tree topology behaves the same in either. The real split is philosophical. EVE-NG is an open, bring-your-own-images platform built for maximum flexibility across many vendors, while CML is Cisco's own turnkey product that hands you a curated, licensed set of Cisco images and a supported workflow. Which one fits you depends less on a feature checklist and more on a single question: would you rather manage the lab environment yourself, or pay Cisco to manage it for you?
The core difference: a toolkit versus a product
EVE-NG (Emulated Virtual Environment Next Generation) is best understood as a platform you assemble. It gives you the canvas, the wiring, the console access, and the emulation engines — Dynamips for classic IOS, IOL/IOU for lightweight router and switch nodes, and QEMU for full virtual-machine images — but it deliberately ships without vendor operating systems. You bring those yourself. That design is exactly what makes it powerful: because any node is just a virtual machine or IOL binary you drop in, you can build a topology that mixes Cisco routers with Juniper, Arista, Palo Alto, Fortinet, VyOS, Linux hosts, and more on one canvas.
CML (Cisco Modeling Labs) is a finished product. Cisco built it, Cisco supports it, and it arrives with a set of Cisco reference images already included and licensed under your CML entitlement. You are not sourcing binaries or wiring up an emulation backend — you launch the appliance, open the web UI, and start dragging nodes. The trade for that convenience is scope: CML is a Cisco environment first and foremost. You can attach external connectors and some third-party workloads, but multi-vendor sprawl is not what it is designed around.
Neither of these is 'the good one.' They solve the same problem from opposite directions — one maximizes flexibility and hands you the maintenance, the other maximizes convenience and keeps you inside Cisco's ecosystem.
Images: who supplies the operating systems
This is the single most important practical difference, and it is where most beginners underestimate the work. In EVE-NG, the emulator is free but the network operating systems are not part of it. You are responsible for obtaining every image — the Cisco IOL files, the qcow2 disks for IOSv, IOS XE, NX-OS, or any other vendor — importing them into the correct directory, and fixing them up so the platform recognizes them. Legally, you are also responsible for having a valid entitlement to run those images; EVE-NG does not grant you any license to Cisco or third-party software. For a working professional with legitimate access to images this is a non-issue, but for a self-funded student it is often the hardest part of getting started.
CML removes that entire problem. It ships with Cisco reference-platform images — a virtual IOS router and Layer 2 switch, IOS XE, IOS XRv, NX-OS, and a virtual ASA among them — and your CML license covers running them. There is nothing to hunt down, no forum threads about which image build actually boots, and no ambiguity about whether you are allowed to use it. For CCNA and CCNP work that focuses on Cisco routing and switching, this is a decisive advantage: the images you need for the exam blueprint are curated, current, and legitimately yours to run.
The flip side is reach. If your studies or job take you into genuinely multi-vendor territory — a service-provider topology with Juniper, a security lab with a Palo Alto firewall, a data-center design mixing platforms — EVE-NG's willingness to run anything QEMU can boot is exactly what you want, and CML's Cisco-centric library becomes a limitation.
Setup, interface, and day-to-day maintenance
EVE-NG asks more of you up front and over time. You deploy it as a virtual machine (on a bare-metal hypervisor, ESXi, or a workstation type-2 hypervisor), size the CPU and RAM yourself, manage the image library, and keep the platform patched. Its topology canvas runs in the browser, but console access historically depends on helper clients or the HTML5 console, and some quality-of-life features live only in the paid Professional edition. The Community edition is fully capable for study, yet you should expect to spend real time on installation, image preparation, and the occasional troubleshooting session that has nothing to do with networking and everything to do with the platform itself. That overhead is the price of flexibility.
CML is built to minimize that overhead. It is delivered as an appliance you stand up once, and from then on you live inside a single polished web UI: drag nodes, draw links, open a console in the same browser tab, start and stop the whole lab with a click. Topologies are stored as portable YAML files, so exporting a lab, sharing it, or importing someone else's is a clean, supported operation rather than a hack. CML also exposes a proper API and integrates with automation tooling, which matters as you move into CCNP-level and DevNet-style work. Because Cisco owns the whole stack, the environment is coherent and predictable in a way a self-assembled EVE-NG install is not.
Put plainly: EVE-NG rewards people who enjoy owning and tuning their infrastructure, while CML rewards people who want the lab to be a solved problem so they can spend their hours on protocols, not plumbing.
Cost, licensing, and support
On cost, the headline is simple but the details are not. EVE-NG's Community edition is free, and a paid Professional edition adds features and higher scale — but 'free' understates the total cost, because you still have to legally source every vendor image, and the paid tier plus your own hardware are real expenses. CML is a paid product across its tiers, and it also offers a free tier with a limited node count for casual use. Exact prices, edition names, and per-tier node and resource limits change over time and are not worth memorizing from any article — check Cisco's current CML page and EVE-NG's own pricing page for the numbers before you commit.
Support and alignment often matter more than the sticker price. EVE-NG's help is community-driven: documentation, forums, and a large user base that has usually already hit whatever problem you have. CML is backed by Cisco itself, its reference images track the platforms Cisco tests you on, and paid tiers come with a formal support path. For a learner who values a low-friction, officially-blessed environment that mirrors the certification blueprint, that backing is part of what you are paying for.
Because both the pricing and the tier structure genuinely do shift, treat any specific figure you read — here or anywhere — as a prompt to go verify on the vendor's site, not as fact.
Which one should you use?
Choose EVE-NG if budget is the constraint and flexibility is the goal. If you want a free or low-cost platform, you already have legitimate access to the images you need, you expect to build multi-vendor topologies, and you do not mind investing time in setup and maintenance, EVE-NG's Community edition will take you as far as you are willing to push it. It is the better fit for tinkerers, for multi-vendor study, and for anyone who wants full control over the environment.
Choose CML if you want an official, low-maintenance Cisco lab and would rather spend your time studying than administering a hypervisor. For focused CCNA and CCNP preparation, CML's included, properly-licensed Cisco images remove the biggest hurdle beginners hit — finding and legitimizing images — and its polished UI, supported import/export, and Cisco backing make it a clean, dependable environment aligned to the exam topics.
For pure CCNA and CCNP routing-and-switching study, either tool will get the job done, and the labs you build will grade out the same because both run real Cisco control planes. Let the tie-break be honest self-assessment: if you enjoy owning the infrastructure and want multi-vendor reach on a tight budget, go EVE-NG; if you want the lab to just work, with legitimate Cisco images and minimal upkeep, go CML.
Frequently asked questions
Can I run Cisco CML or EVE-NG in VirtualBox, or do I need VMware?
CML ships only as a virtual appliance (an OVA or ISO you boot inside a hypervisor) with no native Windows or macOS installer, and Cisco supports it on VMware Workstation/Fusion (now free for personal use) or ESXi, not on VirtualBox. EVE-NG is more flexible about the host but is itself a Linux appliance you run as a VM, so in practice both are things you run inside a hypervisor rather than install directly on your desktop. Check the current release notes before you commit, since supported hypervisor versions change over time.
Do EVE-NG and CML automatically grade my labs the way Packet Tracer does?
No. EVE-NG and CML are emulators running the real network OS, so they do not score your configuration; you confirm your own work with show and debug commands or an external grader. Packet Tracer is the outlier: it is a simulator, but it can auto-grade inside pre-authored .pka activity files that carry an answer key, so automatic pass/fail on real IOS requires a platform that layers grading on top of the emulator rather than the emulator by itself.
If I build a topology in EVE-NG, will it run the same way in CML?
The lab files are not directly interchangeable — EVE-NG uses its .unl format and CML uses its own YAML, and they reference different image names — so you rebuild the topology rather than copy it across. Once running, though, protocol behavior is identical because both boot genuine Cisco images: an OSPF-advertised loopback still appears as a /32 by default, and HSRP still ships with preempt off, no matter which emulator hosts it. Differences you hit are almost always image or CPU/RAM resource differences, not a matter of one tool emulating more accurately.
Why does 'crypto key generate rsa' fail when I try to enable SSH in my lab?
That command is an EXEC (enable-mode) command, not a config-mode line, and it refuses to run until the device has both a hostname and a domain name, because the key label is built from host.domain. Set 'ip domain-name example.com' in global config first, then generate the key from the exec prompt, and remember that SSH will not accept connections until the RSA key pair actually exists. This behaves the same in EVE-NG, CML, and on physical hardware.
Why doesn't my HSRP router take back the active role after it reboots?
HSRP does not preempt by default, so a router that was active, reloads, and comes back with the highest priority stays in standby until the current active device fails — you must add the 'preempt' keyword for it to reclaim the active role. VRRP is the opposite, with preemption on by default, so its highest-priority master takes over automatically. Because these are protocol defaults, you will observe the same behavior in either emulator or on real gear.
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