Just Out: netsim-tools Release 1.1

New Year break was probably my busiest time (programming-wise) in years. Jeroen van Bemmel continued generating great ideas (and writing code and device configuration templates), and I found myself saying, “why not, let’s do the right thing!” more often than I expected. In parallel, Stefano Sasso fixed configuration templates for Junos, Mikrotik Router OS, and VyOS, and we were good to go.

To give you an idea of how fast we were moving: issue #84 was created on December 22nd, Sunday’s pull request that pushed release 1.1 into the master branch was #135 (GitHub numbers everything you do sequentially).

Starting with release 1.3, we renamed netsim-tools to netlab.

In the meantime, we rewrote most of the topology transformation code, changed major data structures, simplified configuration templates, and added BFD support for Arista EOS, Cisco IOS, IOS XE, and Nexus OS, Junos, Nokia SR OS and SR Linux, Mikrotik RouterOS, and VyOS.

You’ll find more details in the release notes; if you’re not familiar with netsim-tools yet, you might want to start with the Installation Guide and Getting Started document.


  1. Hello Ivan,

    Thanks for your great "holydays" work!

    Sometimes we struggle to meet the RAM requirements with large topologies. When using several instances of the same images (VMs, Containers,...), memory page sharing is a great optimization.

    Take a look at:


    It has been a game changer for me! If you don't use it already, consider recommending UKSM for netsim-tools.



    1. Thanks for the pointer -- it looks like once you install UKSM it's mostly behind-the-scenes magic, so I don't think there's any interaction with netsim-tools (which is mostly an abstraction layer and orchestrator).

      I will add a link to the libvirt installation instructions, so whoever wants to go down that path can get it done.

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