Does anyone have any experience running GNS3 locally (on Windows or Mac) vs the VM Workbench? I tend to have larger and larger topologies and my 4GB of RAM get pretty loaded...

Anyway, can workbench calculate and utilize the idle PC value efficiently, and is there a significant performance decrease when using the VM in comparison to a local install?

  • Did you use Vmware Workbench for a long time?
    – laf
    May 28, 2013 at 8:51
  • I did not use it yet at all, I'm evaluating. I would run the GNS3 Workbench Distro (rednectar.net/gns3-workbench) on virtualbox locally and want to know if anyone has done this and has a comparison of processor usage
    – Max
    May 28, 2013 at 9:15

3 Answers 3


I'll go ahead and provide some more "in-depth" instructions on telling GNS3 to use a "remote hypervisor" (a dynamips instance listening on another machine).

You can even use this setup with Amazon EC2 (or another utility computing provider). A setup with a utility computing provider would also be extremely useful for testing out topologies with a very large number of routers, to see how OSPF may behave at scale, etc. I've documented how to do this at my last job (but this was before GNS3 was so popular) and we used it successfully for numerous scale tests. This would also be ideal for folks that don't want to spend the money on a high-end server but can afford to spend a few dollars for a few hours of "server time" for GNS3 labs, without chewing up CPU cycles on their home machines.

The following instructions assume your remote hypervisor is running Linux.

Step One: Set up your Linux box.

jjensen@jjensen-dev:~$ mkdir dynamips
jjensen@jjensen-dev:~$ cd dynamips
jjensen@jjensen-dev:~/dynamips$ mkdir tmp

Step Two: Set up GNS3. Edit -> IOS images and hypervisors. Click the "External Hypervisors" tab. Add in the IP address info for your remote hypervisor (Most of the time you can leave all the fields besides IP address as the default). Once you've filled in the IP of your remote hypervisor, click "Save".

add remote hypervisor

Once you have your remote hypervisor added, go back to the "IOS images" tab and add in IOS images. There are two important bits to remember:

Use the "Linux format" directory notation (see screenshot), and make sure that the "use the hypervisor manager" checkbox is unchecked so that you can select the remote hypervisor that you just added. When adding the IOS image with the remote hypervisor, make sure that your remote hypervisor is selected.

add IOS image

Once you have your IOS image added, start up Dynamips on your remote machine.

jjensen@jjensen-dev:~/network_eng/dynamips$ sudo ./dynamips-0.2.8-RC3-community-x86_64.bin -H 7200 &

You should now be able to add devices to GNS3 topologies on your Windows machine, and GNS3 will communicate with the remote hypervisor on another machine. You also get the console access via PuTTy and such for free as well. Note that there isn't really a "configuration limit" on how you want to add your IOS images and hypervisors. You could even have it so that you have a separate remote hypervisor per IOS image if you wanted. Pretty powerful stuff.

If anyone could add additional answers on how to make this work with JunOS/"virtual" Olive, I think that would also be pretty useful. :-)


I've had a ton of success running either dynagen/gns3 on my local laptop, while dynamips sits on a remote linux server. My server has only 4Gb RAM and an AMD quad core, yet it handles 32+ router topologies with ease. Your .net file simply connects to a remote box. i.e. this part:




The latest betas of GNS3 now also supports idlemax and various other settings to tune youe environment even more. In the past you would've needed to edit the .net file outside of gns3

  • I do like the remote server idea. Do you have the server locally on the same net or do you have it running all over the internet?
    – Max
    May 28, 2013 at 7:53
  • It can be anywhere as long as you have IP connectivity. Out of interest, my server sits in a rack at work so its always available. I then SSL into work and have full connectivity to it.
    – mellowd
    May 28, 2013 at 8:08
  • would GNS3 be generating a significant amount of traffic here? Considering plausability of SSL to a server over a 3G connection.
    – Max
    May 28, 2013 at 8:16
  • Good luck with 3G. I've never measured actual bits transferred, but 3G+SSL sounds like a nightmare for even basic tasks
    – mellowd
    May 28, 2013 at 8:26
  • I guess you would have to look at what GNS3 is actually doing, as in how is it using the remote server. If it is just sending your input/output as a basic text string it could compress it efficiently and 3G would be less problematic I guess.
    – Max
    May 28, 2013 at 8:37

If you have a restriction on CPU/RAM then running GNS3/Dynamips/Dynagen natively rather than in a VM container is always going to use less resources.

The 'GNS3 Workbench' is only really useful when you are someone that perhaps can't install GNS3 on their machine or don't have the required skill (little) to get GNS3 setup yourself.

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