Archives For Network Simulation

open-source network simulation tools that run on Linux or BSD systems

The Cloonix network simulator has been updated to version 29, which adds the ability to save network simulation topologies and node configurations to a directory.

Users may save a network topology and all node configurations to a directory of their choice. They may also load saved topologies into Cloonix so they can restore a network scenario they previously created. The save function of Cloonix v29 supports copy-on-write filesystems and also allows users to save the full filesystems of nodes, if they wish.

This post will work through a detailed tutorial showing how to save, load, and re-save topologies and node configurations using the Cloonix GUI or command-line interface.

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The Cloonix development team recently released a major update to the Cloonix network simulator.

Cloonix version 28 makes major changes to the infrastructure of Cloonix. It changes the installation procedure, the location of Cloonix files on your computer, and the names of the commands used to start and administer Cloonix.

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Cloonix version 28 also makes changes to the features available to users. It adds support for multiple Cloonix servers running on the same machine, and standardizes and documents the new interface types used to connect virtual machines to each other.

Read the rest of this post for more details about what’s new in Cloonix v28.

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I need to determine the maximum number of KVM virtual machines that can run on an average laptop computer. Unfortunately, I cannot find authoritative information about the maximum number of KVM virtual machines that can run on a host computer. Most information I could find about KVM limits does not publish absolute limits but, instead, recommends best practices.

In this post, I will synthesize the information available from multiple sources into a single recommendation for the maximum number of KVM-based nodes that can run in an open-source network simulator running on a single host computer.

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In this post, I will show how to set up data capture in the GNS3 network simulator when using network devices that are emulated by VirtualBox or QEMU virtual machines.

The GNS3 network simulator makes it easy for users to capture and view data passing across the interfaces of devices running in a GNS3 network simulation. The GNS3 documentation covers how to capture data from devices running on Dynamips in GNS3 but the procedures for capturing data from devices running in other hypervisors, such as VirtualBox or QEMU/KVM, are not well documented.

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While GNS3 users may start and stop data capture on Dynamips VM interfaces any time they wish, they must plan ahead when they intend to capture data on open-source routers and hosts running on VirtualBox or QEMU virtual machines.

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GNS3 1.3 will create and manage VirtualBox virtual machine linked clones from within the GNS3 user interface. This simplifies the process of setting up VirtualBox virtual machines in GNS3, which makes GNS3 easier to use for studying the operation of open-source routers, switches, and hosts in network simulation scenarios.

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In this post, I will show how to set up and use VirtualBox linked clones in your GNS3 simulation scenarios and work through a detailed tutorial.

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When testing SDN functions in the Mininet network emulator and viewing captured OpenFlow messages in a packet analyzer such as Wireshark, it is difficult to identify which SDN switch is the source or destination of each captured message.

The only reliable way to identify which SDN switch sent or received an OpenFlow message is to look at the source or destination TCP port of the OpenFlow packets. This is because most OpenFlow messages exchanged between switches and the controller do not contain any other information that helps identify the sending or receiving switch. Neither Mininet nor the Open vSwitch database provides information that might be used to identify the TCP ports used by each switches to communicate with the OpenFlow controller in the network.

This post describes a procedure to map which TCP ports are used on each switch to communicate with the SDN controller in the Mininet network simulation. This procedure will enable researchers or students to study the interactions between SDN controller and switches in a more detailed and accurate way.

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IMUNES on Linux

August 13, 2015

The IMUNES open-source network simulator can now be installed on and run on Linux. Previously, IMUNES was available only for the FreeBSD operating system.

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The Linux version of IMUNES is ready to be used and can set up and run network emulation scenarios. It does not yet have all the features offered in the FreeBSD version of IMUNES but the development team intends make add in more features until both versions support similar capabilities.

In this post, we will show how to install the Linux version of IMUNES on Ubuntu 14.04, look at the tool set used by IMUNES on Linux, and experiment with a simple network simulation scenario.

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In 2014, the GNS3 development team launched a successful Kickstarter crowdfunding campaign to support development of a major new release, version 1.0, which was released in October that same year. I was happy to support the Kickstarter campaign and now I am finally getting around to taking a look at the new version of GNS3.

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The last time I used the GNS3 network simulator, it was at version 0.8.7. After producing version GNS3 1.0, the GNS3 development team has been updating it frequently. GNS3 is now at version 1.3.7.

In this post, I will look at the new version 1.3.7 of GNS3 and evaluate how it works with emulated routers and hosts running open-source software.

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GNS3coverNo Starch Press recently sent me a preview copy of a new book about the GNS3 network simulator, titled The Book of GNS3 written by Jason Neumann. This book covers the new version of GNS3, GNS3 1.x. Here is my review of The Book of GNS3.

The Book of GNS3 effectively serves as a user manual for GNS3. It offers detailed installation and configuration information for GNS3 1.x in one easy-to-access volume. Experienced users will find some new information in this book, especially about the new features available in GNS3 1.x. However, I think the main beneficiaries will be new or inexperienced users of GNS3.

Most users of GNS3 use it to emulate networks of commercial routers from vendors such as Cisco and Juniper. Understandably, Mr. Neumann spends most of the book discussing how to set up GNS3 to run commercial routers and, as much as is possible, switches.

How does this book help those who want to use open-source routers in GNS3? Read the rest of my review to find out.

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The GNS3 development team produced a major new release, version 1.0, in October 2014. Since then, they have been regularly updating GNS3 and, at the time I write this, the latest version of GNS3 is version 1.3.7.

The latest version of GNS3 cannot be installed using a package manager like Ubuntu Software Center or Synaptic because no packages have been created yet for GNS3 1.x. The Ubuntu repository and the GNS3 PPA only provide packages for old versions of GNS3. The latest version of the GNS3 package for Debian/Ubuntu is GNS3 0.8.7.

The GNS3 development team is working on packages for GNS3 1.x but, as of the time I post this, it is not clear when they will be available.

To install the latest version of GNS3 on an Ubuntu Linux system, install the dependencies, download the GNS3 source files, and compile the software. I provide the list of commands in this post.

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Open-source DevOps tools are used to deploy applications and services in datacenter server networks, but they may also enable researchers or students to simulate networks. In this post, we will survey popular open-source DevOps tools and provide links to information that shows how to use them to create network simulation scenarios.

Most open-source network simulators simplify the setup and configuration of virtual machines and the networking connections between virtual machines. DevOps tools such as OpenStack do the same things, although they expose more of the complexities of the virtualized infrastructure to the user.

If you are already using DevOps tools for other activities you may find it useful to also use them when you need to create a simulated network instead of learning to use a network simulator.

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The CORE Network Emulator has been updated to version 4.8. This new version fixes the issues I noted in my previous review of CORE release 4.7. It also implements some new features. See the CORE 4.8 release notes for all the details.

The most visible change is the addition of some new services — most notably a new Docker service that will allow Docker containers to be used as nodes in the simulation scenario.

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