Archives For simulation

related to the network simulators and other VM-management tools

As we work through this tutorial, we will learn how to use the cloonix graph interface to build a simulation scenario that includes two small IPv6 networks connected to each other by two routers via static routes. We will also learn how cloonix saves network topologies and guest virtual machine root filesystems.

Cloonix IPv6 linux network simulation

Linux IPv6 network simulation running on the cloonix open-source network simulator

The cloonix open-source network simulator uses KVM virtual machines in the simulated network so, in this tutorial, we will demonstrate real Linux router and host configuration procedures.

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The cloonix project provides a variety of root filesystems for use in the cloonix network simulator. These root filesystem only have the most basic software packages installed and will not support advanced network configuration (with the exception of router filesystems such as openwrt).

To create a network simulation that runs real-world networking software, we need to install new software on the root filesystems we will use in cloonix. In this example, we chose to start with the Debian jessie root filesystem and we will install some networking software and a desktop environment.

We will also show how to save the upgraded root filesystem for future use as either a static or non-static root filesystem.

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The cloonix development team recently updated the cloonix network simulator to version 24. This post describes the changes in cloonix v24 compared to cloonix v19, which we reviewed in a previous post.

Cloonix open-source network simulator on Linux

Version 24 simplifies the setup of guest virtual machines, improves the link performance emulation tool, and adds new interface types designed to improve packet throughput performance. Users familiar with the cloonix graph GUI will have no problems using this new version, but shell scripts with cloonix ctrl commands may need to be updated, because the ctrl CLI has changed.

Please read on to see a detailed description of the changes.

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Install Cloonix v24

May 18, 2014

The Cloonix open-source network simulator was recently updated to version 24. The last time I used Cloonix, it was at version 19 (see my review of Cloonix and my using the Cloonix graph interface posts). Compared to version 19, only a few details of the installation procedure have changed — the list of package dependencies is different compared to v19.

The Cloonix v24 installation procedure is documented in the README file that comes with the source code. For my own reference, I will describe the procedure, along with some additional information, in this post.

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While working through some of the previous tutorials about the CORE Network Emulator or IPv6, we noticed some strange broadcast packets in the Wireshark packet analyzer that appeared to have nothing to do with the processes running on the simulated network.

Messages generated by the host Linux system that are not associated with any nodes running in the simulated network

Messages injected into the simulated network by the host Linux system

For example, we started a simulation consisting of two nodes connected to the same switch. We started the Wireshark packet analyzer on one of the nodes. No processes are running on the nodes that would generate data traffic on the links between them so we should see no data packets in the packet capture shown above. However, we see many broadcast frames carrying mDNS, NDP, and DCHP requests.

Data passing between simulated nodes in CORE is mixed up with other data packets generated by the host Linux system. Read on to learn how we stop this distracting data.

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The Integrated Multiprotocol Network Emulator/Simulator (IMUNES) is a fast, functional network simulator that runs on the FreeBSD operating system. It was created by a team of researchers and educators at the University of Zagreb.


The IMUNES development team offers a VirtualBox image of a FreeBSD system with IMUNES installed so it is easy to evaluate. We will take a first look at IMUNES by installing this image in VirtualBox and testing a few of the features of this interesting open-source network simulator.

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The Common Open Research Emulator (CORE) is an open-source network simulator developed by Boeing’s Research and Technology division and supported, in part, by the US Naval Research Laboratory. It is a fork of the IMUNES Network Emulator project and it was developed as a tool to support a mobile data networking research project. It can also be used to emulate fixed link networks, which is the use-case we are investigating.

CORE desktop

Common Open research Emulator running on VCORE virtual machine

CORE uses Linux Containers (LXC) as its virtualization method. It provides a GUI tool for creating networks and offers useful functions for inspecting the status of virtual network elements and for running applications and creating traffic in the network.

To test-drive the CORE Network Emulator, I will use CORE to create a simulated network of host computers, switches, and routers. I will run the simulation and show some of the interesting features available in CORE.

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The Netkit open-source network simulator was created by a group of university professors who use it as a tool in their teaching. They created a large number of pre-configured lab scenarios, each with lecture slides that describe the scenario and the technology used in the scenario, and make these assets available on the Netkit web site.

Netkit open source single-area OSPF pre-configured lab

Netkit network simulator running the pre-configured single-area OSPF lab

This library of pre-configured lab scenarios and acompanying lecture slides is one of the key benefits of Netkit. In this post, we will explore one of the prepared labs: the single-area OSPF lab.

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Picture of three virtual machines in the Cloonix graph window

I used the Cloonix open-source network simulator to simulate a very simple network. This helped me understand how to use the “point and click” functionality provided by the graph function to manually build and configure a test network. I also hope that the following procedure would be useful as a simple tutorial for anyone interested in learning to use Cloonix.

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This article describes my first experience with the cloonix open-source network simulator. I installed cloonix on ubuntu 12.04 and tested it by running the demonstration script provided with the cloonix package. The demonstration script sets up a simulated OSPF network and runs HTTP traffic between two virtual computers attached to that network.

cloonix network simulator

cloonix network simulator running on ubuntu 12.04

The cloonix package provides modified versions of networking tools and virtual machine management tools, so one does not need to install a lot of supporting software. The developers also provide filesystems for Linux distributions such as Debian and Vyatta (a Linux router) that can be used in the simulations. More details about what makes cloonix special are available in the online cloonix documentation.

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NetKit test drive

August 25, 2012


Let’s look at the NetKit network simulator first. NetKit offers some useful prepared labs and provides the NetKit files already installed on a Knoppix LiveDVD. These assets make it easy to try out Netkit.

To take a first look at NetKit, we will load the LiveDVD into a VirtualBox virtual machine running on our computer and follow the steps below to run a simple lab using NetKit.

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NOTE updated February 26, 2013: This post contains old information. I created a page that lists all the open-source network simulators listed in the post below. I will keep the page up-to-date. Please see the List of Open-Source Network Simulators page.

I am impressed with the number of network simulation tools available as open-source software. Here are some more tools that allow a user to build a virtual network and simulate network functions. The tools are: Marionnet, Virtualbricks, and libvirt.

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