OMNeT++ is an extensible, modular, component-based C++ simulation library and framework, primarily for building network simulators. “Network” is meant in a broader sense that includes wired and wireless communication networks, on-chip networks, queueing networks, and so on. Domain-specific functionality such as support for sensor networks, wireless ad-hoc networks, Internet protocols, performance modeling, photonic networks, etc., is provided by model frameworks, developed as independent projects. OMNeT++ offers an Eclipse-based IDE, a graphical runtime environment, and a host of other tools. There are extensions for real-time simulation, network emulation, database integration, SystemC integration, and several other functions. OMNeT++ is distributed under the Academic Public License.
Although OMNeT++ is not a network simulator itself, it has gained widespread popularity as a network simulation platform in the scientific community as well as in industrial settings, and building up a large user community.
OMNeT++ provides a component architecture for models. Components (modules) are programmed in C++, then assembled into larger components and models using a high-level language (NED). Reusability of models comes for free. OMNeT++ has extensive GUI support, and due to its modular architecture, the simulation kernel (and models) can be embedded easily into your applications.
The main ingredients of OMNeT++ are:
During the years OMNeT++ has been available, countless simulation models and model frameworks have been written for it by researchers in diverse areas: queuing, resource modeling, internet protocols, wireless networks, switched LANs, peer-to-peer networks, media streaming, mobile ad-hoc networks, mesh networks, wireless sensor networks, vehicular networks, NoCs, optical networks, HPC systems, cloud computing, SANs, and more. Most of these model frameworks are open source, developed as independent projects, and follow their own release cycles.
The INET Framework can be considered the standard protocol model library of OMNeT++. INET contains models for the Internet stack and many other protocols and components. The INET Framework is maintained by the OMNeT++ team for the community, utilizing patches and new models contributed by members of the community. Several other simulation frameworks take INET as a base, and extend it into specific directions, such as vehicular networks (Veins, CoRE), overlay/peer-to-peer networks (OverSim), or LTE (SimuLTE).
We maintain a list of selected OMNeT++ models and model frameworks here.
Here is a a brief overview of the workflow for using OMNeT++:
An OMNeT++ model is built from components (modules) which communicate by exchanging messages. Modules can be nested, that is, several modules can be grouped together to form a compound module. When creating the model, you need to map your system into a hierarchy of communicating modules. (When you use a model framework, this and the next two steps are mostly done for you.)
Define the model structure in the NED language. You can edit NED in a text editor or in the graphical editor of the Eclipse-based OMNeT++ Simulation IDE.
The active components of the model (simple modules) are programmed in C++, using the simulation kernel and class library. C++ classes that represent protocol headers are described in MSG files which are then translated into C++ code.
Provide a suitable omnetpp.ini file to hold OMNeT++ configuration and
parameters to your model. One ini file may hold several configurations which
can build on one another, and may even contain parameter studies.
Build the simulation program and run it. You’ll link the code with the OMNeT++ simulation kernel and one of the user interfaces OMNeT++ provides. There are command line and interactive, graphical user interfaces.
Simulation results are written into output vector and output scalar files. You can use the Analysis Tool powered by Pandas and Matplotlib in the Simulation IDE to analyze and plot them. Event logs recorded from the simulation can be viewed in the Sequence Chart Tool in the IDE. Result files are text-based, so you can also process them with R, Matlab or other tools.
The Simulation IDE is a powerful, feature-rich environment for developing, running, and evaluating simulation models. Please note that using the IDE is entirely optional; model development and execution are also possible and fully supported through the command line or alternative editors/IDEs.
The following video provides a brief introduction to the IDE.
The OMNeT++ simulation kernel is standard C++, and runs basically on all platforms where a modern C++ compiler is available. The Simulation IDE requires Windows, Linux, or macOS.