Viability of GNS3 network simulation for testing features/configurations.

Thu Oct 17 16:08:34 UTC 2019

>
> Said that I haven’t played with GNS3, EVE-NG, VIRL,… recently so I don’t
> know if any of these would allow me to create these massive “spreadsheets”
> for programmatic generation of labs.
>

 GNS3 you can, they have a fairly well documented JSON based API that you
can use to script up all the things, connections, and visual layout as
well.

I've only played with it on a rudimentary level, but it seems to work
just fine.

On Thu, Oct 17, 2019 at 8:14 AM <adamv0025 at netconsultings.com> wrote:

> I’ve been using network simulation well before GNS3 was around using
> dynamips - and even when GNS3 came along it was still not good -since it
> just couldn’t handle the scale (~40nodes) (not on my compute resources at
> that time anyways).
>
>
>
> And similarly nowadays in the era of proper HW simulation through VMs
> (though I miss the idle-pc), I really like virsh/libvirt along with OVS as
> it allows me to programmatically generate the VM files (xmls, images,
> etc..) and define the topology in OVS (talking hundreds of links) which
> would be otherwise really tedious to draw by hand.
>
> Also spinning up a big virtual lab from scratch takes several hours (of
> pure compute time) so it’s better to have some meshing in between the nodes
> and just spin up arbitrary L1 topologies on demand rather than spinning up
> the VMs every time one needs to load a different topology.
>
> Said that I haven’t played with GNS3, EVE-NG, VIRL,… recently so I don’t
> know if any of these would allow me to create these massive “spreadsheets”
> for programmatic generation of labs.
>
>
>
> Best approach is to have at least two virtual environments
>
> 1) closely resembling production environment -this is where designers and
> Ops people can test day to day operational changes etc..
>
> 2) environment where architects can test strategic/evolution changes to
> the network infrastructure, new concepts and big migration/integration
> projects, etc…
>
>
>
> What is it good for:
>
> Testing design concepts
>
> -this is one of the biggest advantages of virtual testing
>
> Physical labs as we all know cost a small fortune and you can simulate
> just a small cross-sections of your overall topology at a time  -but in
> virtual lab depending on your computing resources and depending on what you
> need to test you can either simulate very large sections or complete
> network (at lower resolution) or smaller sections with very high resolution
> or combination of both.
>
> This allows you to really see what happens to your traffic patterns and
> assess the impact of your design changes from small to large scales.
>
>
>
> What is it not good for:
>
> A) Scale testing
>
> i.e. how many bgp/bfd/vrrp/etc.. sessions how many routes/VRFs/etc… - you
> need the actual HW resources to carry out these tests
>
> B) Performance testing
>
> How much pps I can drive through NPU with these features
> (QOS,filters,etc…) what are the failover times, (fast reroute, fabric
> fail,RE fail, etc…) -again you need the actual HW that will be used in
> production to measure these
>
>
>
> But as you can see A) and B) can easily be tested with a single DUT (or
> some small topology around it) using actual HW plugged in a loop with
> IXIA/Spirent testers.
>
>
>
> adam
>
>
>
> *From:* NANOG <nanog-bounces at nanog.org> *On Behalf Of *Ryland Kremeier
> *Sent:* Wednesday, October 16, 2019 4:31 PM
> *To:* <nanog at nanog.org> <nanog at nanog.org>
> *Subject:* Viability of GNS3 network simulation for testing
> features/configurations.
>
>
>
> Hello,
>
>
>
> I’m currently in the process of setting up a near identical network to our
> own in GNS3 for testing purposes. Has anyone here tried this before to any
> success? We need to buy the Cisco IOSv image to continue with the sim so I
> figured I would inquire here first before diving in.
>
>
>
> All info is appreciated,
>
> --
>
> Ryland Kremeier
>
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