Jul 31, 2009 - library development potential is enormous. 13.COMNET 111: This is a trace driven tool sold by CACI. This tool replaces LNETII and COMNET ...
An Overview of Some Network Modeling, Simulation & Performance Analysis Tools Humayun Akhtar, Ph.D AT&T Laboratories 1 Oakway, Berkeley Heights, NJ 07922, USA e-mail: haha @ attmail.com
Abstract: This paper is an overview of more than forty of the leading tools being used in the field of network performance analysis, modeling and simulation. The purpose of this paper is to inform potential users of trends in the industry by providing an overview of some of the capabilities of each tool. With unique knowledge of the tools available and a solid background in mathematical modeling and networking architecture, it is possible to utilize some of these tools to dramatically shorten the time span involved in providing useful network architectural solutions, cost reduction and optimization of network resources. Tools Overview: An evaluation of most of the tools has been conducted. A brief description follows : 1 .Q+: This tool was developed at AT&T Bell Labs and was thefirst of its kind for the 80's which in fact led to the development of some external tools that share some of its central philosophy. It is based upon the use of queuing theory and simulation. Even though it is not very user friendly, it is a powerful engine requiring experienced modeling personnel. Considering the fact that its graphics have not kept up with the pace of commercial tools, user friendly interfaces, it does not present itself as an easily understandable tool for the average user even though some of its features are quite impressive. This tool has good long-term potential and continues to evolve albeit slowly. In its present form it can be used as a back-end for developing simulations of sub-components of customers' extensive networks since the front-end graphics have not yet been developed sufficiently. It is possible to do a variety of simulations using the queueing theory paradigm with this tool if modeling personnel with a strong academic background are available. 2.ATOMS: This is a statistical tool for performing multiple Qf runs for what-if studies and also uses the famous SAS statistical engine to enhance the statistical output of Q+. 3.PAT: This is an analytical performance analysis tool from Bell Labs and could be used to cross-check certain components of a simulation with mathematical formulas. It is an analytic tool for examining the performance of a distributed processing system or an intelligent network. It ocmbines both queueing network and activity network modeling concepts in that both probabilistic branching as well as parallel branching are allowed in describing the message flows of a call. PAT is completely data driven. PAT is used for single dimensional inversion applications. 4.MyPAL: This is another analytical performance analysis tool based upon the theory of transforms in queuing theory and is used again for further cross-checks of performance analysis simulations. It uses an approximation technique defined by the Widder Laplace transform inversion formula for inverting the Laplace transform. It does single dimensional transform inversion. 5.QNA: This is a queuing network analyzer analytical tool. It has been in use at Bell Labs for many years and interfaces with Q+. It is used for obtaining analytical approximations to open queuing networks. 6.PANACEA: This is yet another analytical performance analysis tool used for solving closed queuing networks problems and interfaces to Q+. 7.42 (Q squared): This is a new analytical performance tool that has been developed at AT&T Labs which is supposed to be the 'mother of all analytical tools'. It solves not only steady state but transient and time
0-8186-7852-6/97$10.00 0 1997 IEEE
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dependent queuing situations as well. It does multidimensional transform inversion. Whereas most other analytical tools do essentially M/M/I type systems, this tool does those and BMAP/G/I systems as well. 8.PFM: This tool is referred to its generic name which is product form models (PFM) since a formal name has not been decided yet owing to its relative infancy. It can do some of the features of PANACEA along with blocking calculations. It is being developed along with Q squared. 9.RESQME: This is an IBM simulation tool which has shared some of the ideas of Q+ . It has features similar to Q+ but incorporates some features similar to SES Workbench. It runs in several environments including OS/2. The precursor to this tool was RESQ from IBM. However, this tool 's disadvantage is that it is trace driven versus Q+ which is a real-time tool. A new release for RESQME including real-time animation and additional user-friendly graphics interfaces are in the works. It is the only real simulation tool available in an OS12 PC environment which could be considered an advantage by some. However, using this tool requires experienced modeling personnel as well.
IO.SES: This is a simulation tool which had origins similar to RESQ since the same PhD students who began its development first at University of Texas at Austin under a professor (now owner of SES), also began the formal RESQ project at IBM. Although the tool has a similar look to RESQME, it is quite different in many aspects. It is essentially a general purpose graphical simulation engine for generalized applications. 10.5 ALTIA: This is a user-friendly icon oriented front-end for SES. It enables the user to visualize an .actual animated scenario such as the dynamics of a Burger-Stand which could not be readily understood by a customer in the regular SES icon paradigm. 11.BONES: This is a block-diagram driven simulation tool from Comdisco Systems. It has a friendly user interface and plenty of examples in their applications library. However, it is slow for large simulations that require a large number of nodes in what-if studies. One of its greatest features is a large library of readymade models. Leaming BONES really amounts to learning a new block-oriented programming language, which could be considered a disadvantage by some, if one is to conduct new library design using its designer module. However, with its front-end Plannet module this is not necessary since one can use the ready-made models. Plannet could be used easily by inexperienced personnel requiring quick answers to what-if scenarios already modeled by BONES engineers. Due to various reasons, Cadence, the new owners of the product, have essentially withdrawn the tool from the market with very specialized and limited internal circulation in the circuit and component level market.
11.5 SCRIBE is an add-on developed by a third party vendor for developing applications on a PC for BONES. However, the actual application would still execute on a workstation and not a PC. 12. OPNET: This is an outstanding, high-fidelity, high-precision, reliable, Unix and PC based high-speed simulation tool developed by MIL-3 that can be used for small as well as large networks. It originated out of research at MIT and is still used there and at leading universities, R&D centers, consulting organizations and telecom institutions worldwide. It is based upon the state-machine paradigm. It presents features not easily modeled in BONES such as software protocol modeling. It has a built in proto-C programming capability including a full C language programming facility as well. With the introduction of OPNET 3 .O, it can now be used in both non-programming plug and play as well as full programming modes, giving it unparalleled capabilities in the industry. It also has a world CIA map data-base showing latitudes and longitudes. This tool provides capabilities of modeling with radio and satellite configurations as well, which is not found in the BONES product except as a separate product called SATLAB. It is relatively inexpensive for what it offers. It also has custom Icon editor including open interfaces. It has been in use before BONES, it is well documented, well tested in the field and a proven tool, used extensively by the US govemment, especially in secure network planning which requires stringent military specifications. It's free ready-made libraries are now more extensive than any other product. A special field and management oriented non-developers version of this tool, called PLANNER has now been released on a PC and Unix.
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AT&T and Bcllcore (which has a SS7 custom model of OPNET) have used this tool extensively for various domestic and international projects such as banking, enterprise networks, internet, web-modeling, multi-media exchange, Adapt protocol design studies including custom protocols, wireless, VSAT, defense networks, circuit-switched, LAN-WAN-FDDI, TCP-IP, Routers, Client-Server, ATM, DQDB, Fiber, cellular and wireless, satellite, network management, sniffer interfaces and a whole slew of other applications. It is a high-level as well as low lcvel detailed modeling tool that appears to be one of the few tools designed from the ground up with communications problems in mind. The tool is also one of the few that provides both ease of use combined with high level scientific sophistication and is therefore practically a class by itself, unmatched in the industry especially considering the fact that it is not only one of the cheapest on a relative basis but also comes with fee ready made libraries with on-line code available and open interfaces such as APIs. It appears to be the only tool capable of interfacing with other tools described in this paper in order to provide accurate extended networking solutions such as for backbone network design requiring tariffs and analytical queuing theory based verification. As such its future applications library development potential is enormous. 13.COMNET 111: This is a trace driven tool sold by CACI. This tool replaces LNETII and COMNET 11.5. It is used primarily for LAN/WAN simulation and is a reasonably good tool for entry level networking engineers who do not have a good understanding of networking and want to get some feel of the field. This tool is also useful for obtaining a high level view of networks where precision or accuracy is not an issue. The models provided are mostly approximate delay type models without any code or details provided to the user for verification. In order to do development one has to purchase a separate tool at almost three times the base price and learn to program in Modsim, an object oriented language. The tool interfaces to Quintessential to provide tariffing solutions for small to medium sized networks. Overall, this is a low to medium fidelity tool for entry level networking engineers which is not suitable for situations where accuracy is required or consulting contracts are at stake with respect to accuracy of the deliverables. It is also a suitable tool for drawing basic, non-hierarchical network pictures. However, with the introduction of Opnet 3.0 and Planner (PC/Unix), the advantage that Comnet once had at the PC, low end non-programming, plug and play end has essentially disappeared based both upon technological innovation and cost. Overall, Comnet provides a restricted paradigm in which the user is allowed to make changes through menus. Therefore, custom changes or network designs are very limited in the base version of the tool which could be overcome through the use of the Modsim based development tool. 14.MIND : This tool is used for static simulation of WAN designs based upon tariffs. It is used for conducting static network design studies. This tool is used along with INOS at AT&T Global Network Design Center. It runs on a PC and will shortly be available under the windows environment.
15.INOS: An AT&T internal tool for what-if tariff based static simulation network design studies. 16.MAKE Systems: A suite of static simulation network design tools based upon tariffs. It claims to have accurate vendor specific network design parameters which we have not yet confirmed. But the entire suite of sub-tools appears to be still under development and testing. 17.WANDL: A tool similar to INOS developed by one of the former developers of INOS. It is especially suitable for conducting frame-relay what-if studies. 18.TES Tool: A statistical simulation tool developed at NEC by one of the former inventors of Q+, Dr.Ben Melamed, at Bell Labs. This tool is a specialized tool to be used with some of the other peformance tools and as such does not compete directly with any of them. Essentially this is tool for parameterizing input data to drive simulations. 19.QUEUE: An academic analytical simulation tool developed at a Dutch university available for a modest sum. It can solve a variety of basic queuing theory problems.
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20.M/G/IM+I & GI/MM+I : This tool is used for advanced queuing problems for finite queues with general service and general interarrival times. 2 1.CAPER This tool has been developed at Bell Labs for parallel network programming applications. 22.AT&T Network Flight Simulator: This is one of the most advanced simulation tools out of Bell Labs yet. It is a real-time simulator used mostly for parallel programming applications and is specifically designed for modeling the performance of AT&Ts 4ESS backbone networks. It is built upon the CAPER project. It is currently being adapted for large data base simulations. 23.WITNESS: An AT&T/Istel simulation tool which is used for front-end simulations for BPR. 24.ECLIPSE : A BPR suite of tools from Bell labs. A Q+ interface is also available for it. 25.STELLA / I Think: This is a generalized modeling and simulation tool which could be used for certain types of BPR applications. It was originally developed at MIT between the EE department and the SLOAN school of management and was called DYNAMO. In its present form called STELLA (Z Think), it is a highly interactive tool and very useful for studying the dynamics of certain processes. It uses difference equations to enhance the dynamic simulation interface to users and has an open interface to allow import/export with many popular packages. 26. CRYSTALL BALL/ PowerSim : A tool for characterizing input data with distributions as well as doing probabilistic spread-sheets which could interface to STELLA for what-if studies. It is actually possible to see the distribution of whatever probability distribution formula that is input, such as the Gamma distribution with a certain parameter. It is interfaceable to other tools with an open interface such as OPNET. 27.MOPTSIM: A simulation tool developed in Michigan for conducting adaptive control oriented what-if scenarios in the STELLA/I Think paradigm. 28.SIMNET 11: A generalized simulation engine developed at University of Arkansas and Kuwait Institute For Scientific Research for studying simulation of networks, by Dr.Hamdy Taha, a world famous professor of Operations Research writing the 6th edition of his highly acclaimed book. This is an excellent tool for someone interested in understanding simulation from the bottom up. It's great advantage is that it uses only a few block versus some of the other traditional languages such as GPSS and SLAM. 29.CSIM: A generalized simulation engine based upon process oriented simulation developed at MCC. 30.NSIM: A network simulation engine based upon CSIM developed by NCR (formerly AT&T GIs) for simulating custom network scenarios using product proprietary AT&T information. 3 1.EXAMS V: A tool developed by NCR (AT&T GIs) for network simulation. It is non-graphic. 32.TrafCalc: This is a Bell Labs tool for conducting traffic calculations for Erlang B & C models. 33.TRAFLIB: A Bell Labs tool for conducting a variety of telephony traffic studies. 34.MATLAB: This is a commercially available generalized tool for engineering studies. It is only mentioned here because it could be coupled with one of the forementioned tools such as OPNET owing to its open interface to conduct estimative/ predictive studies for radio-wave propagation in wireless/ cellular communications using its stochastic Kalman Filtering models. 35. Unifit 11: A tool for characterizing data developed by Dr.Law. 36. Modline: this is a French tool to do Queuing theory academic modeling.
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37. Optimql Networks: a new tool appearing on the market that does mostly LAN oriented models and provides RMON capabilities. It is still under development although preliminary versions have appeared. It looks very similar to Comnet. 38.Item 95: this is an internal AT&T tool used for designing hierarchical networks.
39.,Synergist/Quintessential/Autonet:these are PC based tools similar to MIND. 40.JADE: a tool that provides customized circuit switched models. 4 1.Concord: a tool for getting networking profile information including costing. 42.INDT: A suite of network design tools for current and next generation networking technologies from Bell Labs. This tool could be interfaced to OPNET to enhance its usefulness due it open architecture.
Conclusion: We have reviewed more than 40 tools in the field of networking, modeling and simulation. Having a good understanding of some of these tools, it could be possible for networking engineers to obtain a better understanding and insight into alternate networking strategies than without the use of tools. It could also help in cost reduction by optimization of network resources potentially saving millions of dollars that could be lost if networks are designed only based upon rule of thumb estimates. References: 1.OPNET User’s Guide, MIL3 Inc., Washington D.C 2.CACI Class Notes, Caci Inc., La Jolla, California 3 .Bones Product Application Notes, Comdisco, Redwood City, California
Networking, Modeling & Simulation Tools
Networking, Modeling &
AT&T NETWORK FLIGHT SIMULATOR
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