GNS3 – An Interview

It used to be that the only way to get any direct, hands-on experience with any networking gear was to have access to some actual, physical equipment. It was an expensive prospect, and often out of reach for most beginners to invest significant dollars into owning their own lab gear. Back in 2000, when I first got started in this area, there were no companies offering remote rack rentals, there were no good simulators, and there weren’t companies selling refurbished networking products at a deep discount. Ebay was available, but the products you were looking at there were quite often from questionable sources and probably not genuine. Needless to say it was very difficult to gain experience working hands-on with the products you were hoping to get familiar with.

Certification training, especially on a budget, was something that was very difficult to do on your own.

Over the years projects like Dynamips and Dynagen would provide some limited simulation functionality for Cisco IOS, but in 2007 as part of a university Master’s thesis project, Jeremy Grossman would begin developing GNS3.

GNS3 would evolve to become one of the most widely used networking simulators available and many a networking student working towards certification would find it an invaluable resource for learning.

Now, in 2014, GNS3 continues its evolution.

Now, I’m a sucker for a local success story and Stephen Guppy, CEO and Co-Founder of GNS3 is located just south of me in Calgary. I thought I’d reach out to him to discuss the past, present, and future of GNS3 and talk to him a little bit about their role in training and certification for the networking professional.

In The Beginning…

Stephen recounted the story of how GNS3 began as Jeremy’s university project, and while he now remains the sole developer, there have been a number of others involved over the years. After Jeremy moved to Calgary he met Stephen replying to an ad for a roommate. Over the past few years, GNS3 has been primarily a labor of love but recently the two really started to ask the question – “What does the community want from GNS3?”

After surpassing the 10 million download mark, they decided to launch a crowd funding campaign, in the hopes that they might make GNS3 sustainable in the long-term. So far that campaign has been a great success with over 13,000 contributors and over $553K in funding. The midnight launch of the campaign actually broke Crowdtilt (now Tilt) but they were very responsive and had things back up and running quickly. They met their initial goal in 3.5 hours and hit over 100K in 18 hours.

For contributors to the campaign, the first Alpha release of the new GNS3 became available April 1st, 2014, and Beta releases in mid-July. Their goal is to have the first version of the “final” product in December.

Fresh Start

The original GNS3 had become somewhat bloated with redundant modules and was a bit of a patchwork over the years with multiple contributors. For this new iteration Jeremy started from the ground up, with less than 5% of the original code going in. The design goal here was to develop a solid framework that could have modules added onto it. This meant simplicity when adding on support for VMware, HP, Juniper, etc.

The GUI and general feel of GNS3 hasn’t changed much so long time users of the product aren’t going through a huge learning curve with the new version either. The end result is a much more robust tool that takes up fewer resources, loads and runs faster, and is generally a lot friendlier to use.


Jeremy and Stephen had seen some interesting data over the last two years, and that was a steep decline in Cisco usage, with Stephen indicating a 25%-45% decline year over year. As they expanded into markets outside the US, other vendors were more dominant, including huge demand for Juniper and Huawei. GNS3 for many years had been known as a “Cisco” simulator but in reality, they aren’t. Their goal is to be the “CML for all vendors” and be able to offer the network engineer a platform to work on whatever vendor product they require.

The huge surge in virtualization has made it incredibly easy to integrate various vendor systems into GNS3. Not only that but with more and more vendors offering ‘free’ versions of their platforms to use in lab and test environments, access to the software has never been easier.

The L’s – Legalities and Licensing

Stephen admits they rarely have to address any legal/licensing issues because they’ve simply made sure they were always on the right side of the law.

“A lot of the things we provide are fully, freely available for anybody. The vendors provide it. XRV, 1000V, the 3600 series, Cisco provides that for free, online, anybody can download it. All that we are able to integrate within GNS3.”

They also have direct relationships with a lot of the major vendors, including Cisco, having been in talks with the product managers for CML and VIRL, as well as having other vendors approach them directly asking for integration into GNS3. Stephen mentions the relationship with the vendors should be “symbiotic” and in their discussions with various internal product managers, etc. all have indicated that GNS3 has value for them, providing highly trained people and a platform for test and development.

“We never want to do something illegal and be taken down because a lot of people depend on our product.”


“I hope Cisco pushes the boundaries, GNS3 has needed a little competition.” Stephen says, laughing. Having known about CML and VIRL for a very long time due to their relationships within Cisco, they’ve been very excited for release of these products. Stephen calls these a “declaration to all the other vendors” and a challenge to them to provide the same level of support for the network professional.

CML, the paid, TAC-supported platform has already been released, but VIRL – the free, community-supported platform remains vaporware. However, should Cisco decide to release VIRL sooner than later, I wondered how a “free” product would impact them?

Stephen admits these products will impact GNS3 in some way, as a competing product, but a lot of the feedback from those with early access to these new platforms seems to be that while they were generally good products, people eventually moved back to GNS3.

“Cisco is building a whole new community from the ground up and that’s not easy.”

The Community

In 7 years the GNS3 community has evolved to a group that has very knowledgeable people who understand the product very well.  Stephen says plans here are to really nurture this relationship and harness the people within the community, starting with a “legitimate, real community portal”. He cites Thwack (the Solarwinds community portal) as an example.

“You help out, you get points, you get a t-shirt.”

Long-Term Strategy

I’ll admit that over the course of the interview with Stephen I learned a lot about the product that I didn’t know. I had been guilty of seeing GNS3 as a “Cisco simulator” but learned that their focus has not been single-minded, and that support for pretty much any vendor was their goal.

Training and Certification remain a huge part of what they are focused on. Plans include a full CCNA platform including labs and documentation, all for free.

“We want to provide all the material and all the resources you need in order to get your certifications. We would love to do it all the way up to CCIE and equivalent expert certifications in all fields, and provide it for free. All you have to do is be a part of the community.”

This is huge. As anyone who has set a goal for a particular vendor certification, the costs associated with the training and studying are sometimes a limiting factor. For GNS3 to be able to offer community-driven material as well as a platform for labs, is incredible and speaks volumes about the goals Jeremy and Stephen have for their software.

“Networks run our lives. They make our lives possible and the network professional, while it is a very thankless task, is probably one of the most important, or I think the most important profession in the world. Vendors make it extremely difficult for them to be good at their job and I think that’s a huge miss from them. We look at training not as a source of revenue but just as something that needs to be done. Someone needs to step up and be able to provide all of this, and we have the eyes on us to be able to do that, so that’s the ultimate goal.”

“You never have to pay for training again, if you chose to.”

As the new product evolves it’s plain to see that these guys are passionate about what they are doing and the energy they are putting into this new iteration of their product is tremendous. The GNS3 brand itself has undergone a massive overhaul as they reimagine themselves not only as a training tool but as a legitimate choice for network modeling, development, proof-of-concept work, etc.

It’s clear that as GNS3 evolves from “that Cisco simulator” into a full-fledged multi-vendor, multi-purpose network virtualization platform that it seeks to become a core component of every network professional’s toolset.