<font size=+4>Notes about network simulators

Notes about network simulators

Compiled by Thierry Ernst - INRIA Sophia-Antipolis
MISTRAL Team - France


1.  Introduction

The aim of this compilation is to overview some of the simulators currently available. It focuses on network simulators specifically and summarizes the information available so far about some of the most popular ones. It gives a description of the simulator, its use and target, the tools provided with it and try to describe the simulation engine and the implementation of the network components to be simulated.

This compilation doens't pretend to be exhaustiv since many research centers have designed simulators for their own purpose and specifically designed for the simulation of a particular protocol or problem. This results in a plethora of simulators, sometimes based on a more general one or a common initial framework that evolved differently over time, which where not intended to evolve and are unsuitable for other simulations. Moreover, the documentation available is often sparse and poor, or confidential, bugs are not fixed, later versions are not made available and the simulators have not evolved with the protocol they were intended to simulate at the time being.

As a result, some simulators are better described than the others in this compilation which retained only those where enough information was provided to understand their purpose and operation. I have sometimes added some comments.

The following were considered:

Links to the appropriate web sites were to find more details are always given for each simulator presented here. There is an interesting web site that points to some of them.

2.  MIT's NETSIM 3.1

NETSIM is an event driven simulator for packet-switched networks designed at the MIT LCS Advanced Network Architecture group for their personal use. The simulator isn't intended to evolve, but is made freely available here to anyone interested. The documentation mentions the latest version 3.1 (25/5/94), but it doens't seem to be available on-line.

3.  NIST

The National Institute of Standards and Technology (NIST) has developed its ATM network simulator for studying and evaluating the performance of ATM networks and is based on NETSIM developed at MIT. The user manual and the source code are freely available. It gives a good example of use of NETSIM.


CPSim is a parallel general-purpose simulation tool commercially available created by Groselj Boyan (BoyanTech Inc.)


INSANE is a network simulator designed at University of California at Berkeley in 1996.

6.  NEST 2.5

NEST was developed at Columbia University department of Computer Science and stands for NEtwork Simulation Testbed. Code and documentation are freely available. The tool is targetted for simulating and prototyping distributed algorithms and systems.

7.  REAL 5.0 (08/97)

REAL (REalistic And Large) is a network simulator written at Cornell University by S. Keshav and based on a modified version of NEST 2.5.

8.  NS version 2.0 (VINT project)

NS is a object-oriented discrete-event simulator for networking research based on REAL. Initially, NS version 1.0 was developed by the Network Research Group at the Lawrence Berkeley National Laboratory (LBNL). Its development is now part of the VINT project under which NS version 2.0 was released.


OPNET (Optimized Network Engineering Tools) is a commercial tool from MIL3 Inc. It is being developed for almost 15 years. As everyone should guess, no much technical detail are available about the internals.

You can find some more information about OPNET compiled by UCL (University College London).

10.  Other simulators and links

There are many more simulators. I have just listed some of them. Note that various people named their simulator NetSim, not necessarily derived from the initial MIT's, which adds some extra difficulties to clear one's mind in this plethora of special purpose simulators.

Last modified: 31 August 2000

Thierry Ernst - Thierry.Ernst@inrialpes.fr at Inria Sophia-Antipolis for Projet Mistral

File translated from TEX by TTH, version 0.9.