Many network engineers, Cisco students and people just interested in networking
has used GNS3 in the past for studies and Proof of Concepts (PoC). Despite it
being a CPU hog, bugs in the Ethernet drivers and lack of stability it has
been a vital tool to not have to invest large sums of money into real hardware.

The legality of GNS3 has always been an issue, GNS3 claims to have good relations
with Cisco which might be true because Cisco knows the value of people being
able to practice on their products. GNS3 is just a GUI and they don’t provide
any images so they aren’t doing anything illegal.

Crowd funding

A while back GNS3 decided to crowd fund their new release called 1.0.
The main selling point was that they are adding switching. I was skeptical of
this right from the start. GNS3 has always claimed that they can’t support
switching outside of ESW cards due to not being able to emulate ASICs.
What has changed now? From the GNS3 official FAQ:

Q. Will you support Cisco switching?

A. Switching is going be supported in GNS3 using L2IOU images, which are special IOS images made to work on PC/Linux. These are more like generic Cisco switches with most of the same features as in real switches. So in the end you can have 90% of the same features, just a bit slower.

Switching will be supported through L2IOU images. For those of you not familiar
with L2IOU, it is a binary running on Linux which is used in the CCIE RS lab in
the troubleshooting section. This is an actual binary so it is not emulating the
hardware. Because the ASIC is not emulated some features are not supported such as
Q-in-Q, QoS and private VLANs.

What’s the problem?

The problem is that this is a Cisco internal software. To run it you must have the binary
and a license. This software is not allowed to run outside of Cisco. Doing so would be
an illegal act unless Cisco opens up for it. But why would they when they have CML coming

GNS3 is just a GUI

Yes, GNS3 is just a GUI. In the past they have been able to avoid legal issues by users
downloading IOS images (which they have the right to). With L2IOU it’s a totally new
ball game. By adding support they are in fact encouraging users to use illegal
software, IOS images could be acquired legally but L2IOU images can not.

Come clean GNS3

I decided not to contribute to GNS3 because I don’t think they were fair in
the crowd funding part. Switching was the main selling point, lets be honest.
Most people donated because of that, I could have donated because I like the
software but I don’t like how GNS3 are playing their cards right now.
It’s time to come clean GNS3!

GNS3 – It’s time to come clean
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6 thoughts on “GNS3 – It’s time to come clean

    • February 21, 2014 at 10:33 pm

      Absolutely Stephen. I’ve sent you a mail and I’ll put the response up here later if you wish.

  • March 18, 2014 at 11:19 am

    What was the outcome of your conversation with Stephen ?

    I’m looking forward to the end of the month to see what we get in v1.0

  • April 20, 2014 at 9:55 am

    I contributed to the early release. I am disappointed to learn about the additional requirements that were not mentioned prior to the release.

    I have posted a couple of comments to GNS3 and actually requested my money back. Complete waste of time thus far.

  • June 12, 2014 at 12:56 pm

    Why start a rant and not update it, I assume the chat with Stephen went in Stephen’s favour?


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