Choosing between GNS3 and EVE-NG is not a fight between sides, it is a decision of context. It depends on your goals, your budget and the type of laboratory that you need to build to learn, practice, or prepare for certifications. If you've ever seen comments like "X is better than Y," you know they're not very helpful.
To put things in order, here you will find a complete and practical comparison based on what really matters: Simulation vs. emulation, ease of installation, performance, scaling limits, cost, required hardware, support, and real-world use casesWe'll also look at where Cisco CML fits in, what about PNET Lab, and what to choose based on your level (CCNA, CCNP, CCIE, automation, or teaching).
Simulation vs. Emulation: Why It Makes a Difference
Before comparing GNS3 vs EVE-NG, it is important to be clear about the framework: Packet Tracer and NetSim “simulate” behaviors, while GNS3, EVE-NG and CML “emulate” real systems.This isn't a minor nuance; it affects your learning and what you can reproduce in the real world.
Simulation tools attempt to mimic devices without running the actual operating system (IOS, ASA, etc.). They are useful when starting out: concepts, basic commands, and lightweight labs that run on almost any laptop. But they fall short when you need to test complex functions, deep debugging or behaviors under load.
Emulation runs the real operating system inside a VM. The result? Real boots, real bugs, real CLI and very close to production scenariosIf you aspire to CCNP, CCIE or replicate environments with multiple vendors, sooner or later you will need emulation.
There's a reason some instructors still opt for simulation: everything seems “cleaner” and smoother. But that's the problem: the real web isn't clean. Sometimes the most valuable thing you learn comes from hours of troubleshooting, and you only get that with emulation.
GNS3 today: solid to start, short to climb
GNS3 was the gateway for many people. It still works well in small topologies, especially if you're using older technologies or images. The community exists, and there are plenty of resources to get started without spending a cent.
Its strengths remain in force: It's free, relatively lightweight for basic labs, and has plenty of community resources.. Additionally, the client allows you to upload images from the interface itself, making it easier to get started if you're not yet familiar with Linux.
Where is it weak today? In what It is not intended for large multi-vendor labs or advanced scenarios.. Project management in the GUI can become cumbersome, “well-done” installations still struggle, and native support for SD-WAN, automation, or remote deployments is limited. Once you get into ambitious topologies, you will notice the seams.
The risk with GNS3 is falling into the comfort of the known. If your goal is to become a professional and working with modern environments, you may have to leave behind what worked for you years ago and make the leap to more current tools.
EVE-NG: The de facto standard for advanced labs
EVE-NG has earned its fame because it fits the needs of hard-pushing engineers: scalability, multi-vendor and web access to work from anywhere. It doesn't boast about being "pretty," it boasts that you can build, break, and debug just like in production.
Its advantages make the difference: Labs that feel real, support for multiple manufacturers (Cisco, Fortinet, Palo Alto, Linux…), a complete web interface, and easy to set up on a remote server and leave it “always ready.” If you're coming from GNS3 and were short of breath growing up, here you take a deep breath.
For CCNP/CCIE levels or tests SD-WAN, switching, complex routing and automation, EVE-NG fits like a glove. Plus, its Pro edition adds amenities for teams and trainers, but even the Community edition is surprisingly capable for serious individual use.
Cisco CML: Official and Convenient, but with Limits
CML (Cisco Modeling Labs) is very eye-catching because it comes from Cisco and comes with official images. It's easy to get started and convenient for "pure" Cisco labs routing, switching, and basic layouts. The HTML interface is helpful, and getting started is pretty straightforward.
Now, it is a closed garden: Total vendor lock-in: no Palo Alto, Fortinet, or Linux boxes. Imaging flexibility is what Cisco gives you, and when you try to grow in lab size, the performance does not shine. There is also no community comparable to GNS3/EVE-NG and, on an economic level, you pay more for less margin if your goal is to mix technologies.
Extra useful practical details that you should know: CML can be installed on bare metal, VMware ESXi, Workstation or cloud (AWS)At the hypervisor CPU level, it requires Intel with VT-x/EPT. Supports multi-user, shared labs and clustering (depending on the edition), integrates packet capture, offers link quality, delay, loss and jitter and allows you to export/import startup configurations. In terms of licensing, the Personal+ variant is around figures such as 349 USD without taxes, and the Enterprise requires a corporate budget. There is also a very limited free edition to 5 nodes (IOSv, IOSvL2 and ASAv) for you to test the flow.
PNETLab: Good idea, half-baked execution
PNETLab was born as an attractive clone-remix of EVE-NG: free, web-based and with a familiar interfaceBut over time it has come to a standstill: without clear roadmap, no strong community, with delicate compatibility and security concernsFor a personal experiment, it might be worth it; for a real investment of your study time, not so much.
Where you can install each platform and on what hardware
EVE-NG shines for its deployment flexibility: bare metal, VMware ESXi, Workstation, Proxmox, VirtualBox, Hyper‑V and cloud deployments. GNS3 is also varied (bare metal, VMware, VirtualBox, Hyper‑V and cloud options), but remember that requires your desktop client for the day to day.
CML, for its part, supports bare metal, ESXi, Workstation and AWSAt the hypervisor level, there is an important difference: EVE-NG and GNS3 run on Intel and AMD (AMD‑V), while CML requires Intel with VT-x/EPT. This may depend on your hardware or the vendor you run it on.
Regarding minimum requirements to start: with GNS3, 8 GB of RAM and 4 cores are the minimum decent and SSD almost mandatory; for serious labs, it's better to go up to 16 GB and CPUs type i7/Ryzen 5 or higher. EVE-NG can boot CCNA with 8 GB/4 vCPU, but for CCNP/CCIE you will want 16-32 GB, 6-8 vCPU, and 100+ GB SSD, and if you are going to connect physical equipment, a best Ethernet switch. CML runs at 8GB/4 cores as a base, and appreciates 16GB if you're going to exceed 10-12 devices.
Be careful with the cloud: many providers block the nested virtualization (AWS, Azure, and the like), which can leave KVM running at half speed. Some have managed to run EVE-NG on GCP without any problems, but use it as warning, not as a vetoIf it suits you, renting a server and accessing it through a browser is a great idea for prevent your laptop from smoking.
Connectivity, capture and lab functions
As for how you connect to nodes, CML offers console and VNC; EVE-NG (Community and Pro) adds console, Telnet and VNC; and GNS3 also adds integration with PuTTY if you're on Windows. To get traffic out, CML pulls external connector, while EVE-NG and GNS3 include the typical NAT Cloud to get out onto the internet without breaking your head.
Packet capture is another point of difference: CML integrates it as standard; EVE-NG Pro and GNS3 rely on it. Wireshark; the Community edition of EVE-NG does not have it built in. For environment manipulation, CML, EVE-NG Pro, and GNS3 allow play with link quality, latency, loss and jitter for realistic scenarios. You will also find multiboot configuration per lab, export/import of configurations and, in backups, EVE-NG incorporates integrated copies while GNS3 and CML depend on the backup of the VM itself.
EVE-NG Community vs Pro: When is it worth paying?
The Community Edition of EVE-NG offers much more than it seems: Unlimited labs, real CLI, multi-vendor support, routers/switches/firewalls, and Linux nodesWith this you can cover from CCNA and CCNP to a large part of the tasks of CCIE Enterprise, if you organize yourself well.
What does the Pro unlock? More agile topology editing, multi-user management, and more convenient file and image handling. and native support for containers and Windows. For an individual user, it's not essential; for trainers and teams, Mark the difference. The Community limits, for example, 63 nodes per lab (the Pro goes up to 1024), it does not allow you to link interfaces of devices that are already on, only allows one user at a time and restricts it to a single running lab.
In terms of cost, the Pro moves in approximate figures of the order of 150–173 EUR/USD per year depending on the modalityThe Community is free and sufficient for most dedicated solo students.
Costs compared and what each includes
GNS3 is 100% free and open source. EVE-NG has Free Community and a paid Pro version with extras. CML does not have a free tier (except for the 5-node educational demo) and its personal license ranges from 199–349 USD/year. If you look at price alone, GNS3 and EVE‑NG Community win; if you look at price vs. multi-vendor flexibility and scaling, EVE‑NG comes out very well.
Another key point is the availability of images: neither GNS3 nor EVE-NG include Cisco images by default (you must provide them), while CML does bring official images. If you need to meet corporate licensing requirements, that may tip the balance towards CML in the short term, although you lose versatility for multi-vendor environments.
Image support and how to upload them
In CML, Cisco images (IOS/IOS‑XE/NX‑OS/ASAv/FTDv/FMCv, etc.) are natively supported, and there is also functional support for Cisco SD‑WAN (vManage, vBond, vSmart, vEdge). However, ACI is not supported in CML, EVE-NG, or GNS3. In EVE-NG and GNS3, Cisco and third parties are supported, but You must provide the images.
Uploading images in EVE-NG requires minimal Linux knowledge: SFTP with FileZilla + SSH to leave them in the folder indicated by the documentation, and that's it. In GNS3, you can load the VM from the client itself, although it may require some fine tuning according to the manufacturerIn practice, EVE-NG usually requires less tuning once the correct image has been imported.
Size limits, multi-user, and clustering
If you need large labs or to work with more people, keep these limits in mind: EVE‑NG Community reaches 63 nodes per lab, Pro reaches 1024; GNS3 does not impose a strict software limit (the real limit will be set by resources); in CML Personal+ the maximum is around 40 nodes, and the Enterprise edition goes up to 300. In multi-user and shared labs, CML and EVE‑NG Pro do support it., while the EVE‑NG Community and GNS3 have more manual approaches. In clustering, CML, EVE‑NG Pro and GNS3 support it (with nuances by edition).
What to use depending on your goal
If you are just starting out with CCNA, you can start with Packet Tracer for the basics and when you want more realism, transition to the EVE‑NG CommunityIt's lightweight for your computer and gives you access to the real CLI, which is what will really make you improve.
For CCNP, the logical path is EVE‑NG (Community or Pro): Complete protocols, realistic topologies, and a mix of vendors. GNS3 is starting to suffer in terms of scalability and orderliness with large labs, and CML closes the door if you want to leave Cisco.
If you aim for CCIE, the normal thing is to use EVE‑NG (ideally Pro or on a dedicated/cloud server)You need to simulate large environments, multiple technologies at once, and realistic failure scenarios. At these levels, GNS3 and CML fall short in flexibility or scale.
Automation/DevNet? EVE‑NG Pro fits very well for containers and multi-user management; CML It's also a good fit if you stay at Cisco, but remember the vendor lock-in. If you're a trainer and share labs, EVE‑NG Pro It makes permissions, concurrent sessions, and collaborative editing much easier for you.
For small labs on your laptop, both GNS3 as EVE‑NG Community They work; if you plan to grow or want to work remotely from your browser, EVE-NG leaves the path clear for you.
Installation and minor drawbacks to keep in mind
EVE‑NG can be installed from OVF on VMware or via ISO on bare metal. Getting started is quick, and you'll be drawing topologies in just a few minutes (once the images are uploaded). GNS3 offers an installer. All-in-one on Windows/macOS, and the GNS3 VM is supported on ESXi and some bare-metal vendors. The downside to GNS3 is that fine-tuning the installation in 2025 is still tricky depending on security policies, firewall or corporate laptop.
A reminder for cloud deployments: many hyperscalers do not expose the virtualization instructions (already in a VM), so Qemu/KVM may be slow or not even start. Working setups have been seen on GCP, but take it as possible option, not universal guarantee.
Performance, realism and “real” learning
In the end it's not just about getting started, but about you learn what you will experience in productionWith EVE‑NG and CML you can reproduce delay, loss and jitter, make integrated captures or with Wireshark and manage startup configurations. GNS3 shares many of these pieces, but when you grow into devices, services, and manufacturers, The experience in EVE-NG is generally more stable and organized for large stages.
Plus, running it on a server and accessing it through a browser takes the pain away: You don't burn your laptop, you can connect from anywhere, and your lab "lives" even when you close the lid. If you're going to invest hours and hours, think about it seriously.
Notes and nuances that will save you time
There is no perfect tool and everyone has their own “art.” EVE‑NG Community lacks certain flourishes (multi-user, hot-link editing, etc.), but it offers everything you need. GNS3 is fantastic if you're coming from legacy environments or simple labs, and CML is very convenient if you need official Cisco images without fighting for licenses.
If you find any data that needs to be refined, Good vibes feedback is always welcomeAnd if anyone has solid experience with ContainerLab and wants to share it, that's gold for anyone considering that approach. Finally, remember that Cisco has a very limited free version of CML to 5 nodes (IOSv, IOSvL2 and ASAv) for you to try without paying.
The choice is quite clear by profiles: GNS3 is a great starting point If the budget is zero and your labs are modest; EVE‑NG is where you really grow, for scale and realism; and CML fits If you need the convenience of official images and don't mind staying within the Cisco universe. Whatever you choose, don't let the installation slow you down: What will make you better is to practice consistently, break away without fear and get used to the “dirt” of real networks.
