GNS3 Alternatives Compared: EVE-NG, CML and Containerlab

GNS3 is free and open source, so the main GNS3 alternatives are other ways of building the same kind of lab: EVE-NG, which puts every topology on one server behind a browser canvas; Cisco Modeling Labs (CML), Cisco's own platform with licensed Cisco images; and Containerlab, which defines a lab as a YAML file. A fourth option keeps GNS3 and changes where it runs, because a lot of GNS3 trouble comes from the VM and the laptop, not from GNS3. CloudMyLab hosts EVE-NG, CML and GNS3 and can host Containerlab labs for you, and we are an official EVE-NG hosting partner, tested and approved by EVE-NG Ltd.

Table of contents

• GNS3 alternatives at a glance
• EVE-NG Pro: one server, every lab, in a browser
• Cisco Modeling Labs: Cisco's own lab platform
• Containerlab: the lab as a YAML file
• GNS3 on a hosted server: the alternative that keeps your labs
• Lab as a Service: when the lab is the work you want to skip
• Which GNS3 alternative fits your lab?
• Run your failing lab on the trial

GNS3 alternatives at a glance

CloudMyLab hosted emulators run EVE-NG, GNS3 and CML on our virtual machines or bare-metal servers, and you upload and install your own images.

EVE-NG Pro: one server, every lab, in a browser

EVE-NG is the closest alternative to GNS3. Both run QEMU images, so most routers and firewalls you run in GNS3 can run in EVE-NG too. The difference is the shape of the tool. GNS3 pairs a desktop GUI with a server, while EVE-NG puts every topology on one server and gives you a canvas in the browser: it describes its interface as a "Full HTML5 User Interface".

That shape suits teams. GNS3 2.2 lets several clients connect to one server, and its documentation is plain about the trade-off: "There is no user isolation, all users can view all projects and modify them." GNS3 3.x adds users, groups and roles. EVE-NG's role-based licensing (RBL) has admin, editor and user roles, and our EVE-NG Community vs Professional guide explains the editions.

Hosted EVE-NG Pro runs EVE-NG Professional on a bare-metal server or a dedicated cloud instance, on a monthly or yearly subscription, with a 24-hour free trial. For the full head-to-head, see our EVE-NG vs GNS3 comparison.

Cisco Modeling Labs: Cisco's own lab platform

CML is the alternative if your labs are mostly Cisco and you want Cisco's own images. Cisco licenses its CML reference images for use only within CML, so they come with the platform rather than as files you move between emulators. CML-Free runs up to 5 nodes at a time, the paid CML Personal ships with 20 Cisco nodes and Personal Plus with 40, and CML Enterprise is the tier built for organizations with many users. Our guide to the Cisco CML editions lists the node limits and users per tier, and GNS3 vs CML compares the two directly.

You bring a CML license bought from Cisco, because we do not resell them. We run the platform as hosted Cisco Modeling Labs, without any affiliation with Cisco, and hosted CML is included in the 24-hour free trial.

Containerlab: the lab as a YAML file

Containerlab changes where the lab lives. A Containerlab topology is a YAML file: nodes, images and links. One deploy command builds it, and Git keeps its history, so the lab can be reviewed and rebuilt like code. Containerlab itself is open source under the BSD-3-Clause license.

It runs container-native network operating systems directly, and it runs VM-based images by wrapping each VM in a container through vrnetlab. The wrapper does not make a VM lighter: the VM inside still needs its own CPU and memory and KVM on the host, so a lab of Cisco VM images needs at least the server it would need in GNS3. Containerlab is driven from the Linux command line rather than a canvas. If labs as code is where you are going, we can host Containerlab labs for you on managed infrastructure.

GNS3 on a hosted server: the alternative that keeps your labs

If your projects already live in GNS3, check whether the problem is GNS3 or the machine under it. GNS3's upgrade guide says the GNS3 VM version "need to be the same version as the GNS3 client", and its troubleshooting guide names another hypervisor holding the CPU's virtualization as a cause of a VM that will not start. A laptop also runs out of memory: GNS3 recommends "4GB of free memory" for the GNS3 VM, and every router you start needs memory of its own, which has to come from the same machine. On an Apple Silicon Mac, x86 images need an x86 host.

None of those needs a new emulator. CloudMyLab hosted GNS3 runs the server on our hardware with virtualization already working, on a month-to-month subscription, and you reach your labs from a web browser. Your labs stay GNS3 projects and your CLI skills carry over; you upload your images to the hosted server once. Our guide to running GNS3 in the cloud compares hosted GNS3 with building your own cloud server.

Lab as a Service: when the lab is the work you want to skip

If the hours go into building the topology rather than using it, Lab as a Service hands the build to us: you describe the topology, we build it, and you can change it whenever your testing does. It suits teams that need a working lab for testing or training more than they need to run one.

Which GNS3 alternative fits your lab?

If you want one server for every lab or a browser canvas, move to EVE-NG Pro, and add role-based licensing if your team needs separate roles. If your labs are Cisco-only and you want Cisco's images, move to CML with your own Cisco license. If you want labs in Git and deployed from a file, use Containerlab. If GNS3 itself suits you and the VM, the laptop or the Mac is the problem, keep GNS3 and move it to a hosted server. If you are only starting CCNA practice, our GNS3 vs Packet Tracer comparison covers that choice. For the same question from other starting points, see our EVE-NG alternatives and Cisco Modeling Labs alternatives guides.

Run your failing lab on the trial

Use the failure you have as the test. If the problem is capacity, load your largest real topology. If it is a console that will not connect, a packet capture or a permission, make that exact operation part of the trial. Two routers pinging each other prove very little.

Bring the topology that broke: hosted EVE-NG Pro and hosted CML have a 24-hour free trial, and hosted GNS3 runs month-to-month.

Frequently Asked Questions

What is the best alternative to GNS3?

It depends on what you want to change. EVE-NG Pro gives you one server with a browser canvas, and team roles with role-based licensing, Cisco Modeling Labs gives you Cisco's own licensed images, and Containerlab defines labs as YAML files. If the problem is the GNS3 VM or your laptop, GNS3 on a hosted server keeps your existing labs.

Does GNS3 support multiple users?

It depends on the release. In GNS3 2.2, several clients can share one server, but every user can see and change every project. GNS3 3.x adds users, groups and roles. For roles on a platform built around them, hosted EVE-NG Pro with role-based licensing and hosted CML Enterprise are the options.

Can I move my GNS3 images to EVE-NG or CML?

Most QEMU disk images you run in GNS3 can also run in EVE-NG once you create a template for them; the GNS3 project itself does not move, and the license terms of each image still apply. CML works differently: Cisco licenses its CML reference images for use only within CML, and adding images of your own to CML means building custom node definitions.

Is there an online or cloud version of GNS3?

GNS3's server can run on a remote machine while you work from your own computer. CloudMyLab hosted GNS3 runs that server for you, and you reach your labs from a web browser on a month-to-month subscription.