Simulador MPLS para la Innovación Pedagógica en el Área de
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1. Quality of Service 2 by means of flows differentiation and resources reservation Moreover it eliminates the problem of managing different control planes that take place in IP ATM networks providing mechanisms to achieve the convergence of both technologies MPLS acts as link between network protocols and the corresponding link level protocol To do it the MPLS header is located after the network header and before the link header 3 in the frame structure In fact MPLS packets forwarding is based on labels and not in the analysis of encapsulated data from upper levels It is a multiprotocol technology that supports any network protocol as well as any technology in M Dominguez Dorado belongs to DISIT at Universidad de Extremadura Avenida de la Universidad s n CP 10071 Tlf 34 607 417 860 Fax 34 927 257 202 e mail mdomdor unex es F J Rodriguez P rez belongs to DISIT at Universidad de Extremadura Avenida de la Universidad s n CP 10071 Tlf 34 927 257 195 Fax 34 927 257 202 e mail fjrodri unex es J Carmona Murillo belongs to DISIT at Universidad de Extremadura Avenida de la Universidad s n CP 10071 Tlf 34 625 943 308 Fax 34 927 257 202 e mail jcarmur unex es J L Gonzalez Sanchez belongs to DISIT at Universidad de Extremadura Avenida de la Universidad s n CP 10071 Tlf 34 927 257 195 Fax 34 927 257 202 e mail jlgs unex es lower layers link or physical In this way an attractive mec2. It also establishes the associations between either the clock and the elements or the collector and the elements The overall functionality is implemented in TTopologia class To carry out these tasks each element has to use a unique identification which is assigned by the identifier generator that belongs to the topology B Simulation scene The scene is implemented as a TEscenario class that contains all components of a simulation environment for instance clock collector topology identifiers generator links nodes etc This means that the overall components in a scene are stored in a single object The most important method in the scene is called generarSimulacion It starts the simulation after the topology clock is turned on In fact everything needed to operate is contained in TEscenario object even the user interface doesn t exist This means that one can create an event interpreter easily where users with visual limitations could get an adapted interface Even it is possible to separate events generation from their visualization and execute them in different hosts V TEACHING AND RESEARCHING APPLICATIONS OF OPENSIMMPLS The main goal of OpenSimMPLS is to be useful to university professors as a tool for teaching innovation 13 It also allows analyzing the operation of MPLS networks via a multilingual and multiplatform system OpenSimMPLS will be shown in Spanish language if that one is the operating system configu
3. Magazine vol 41 Issue 10 Oct 2003 pp 126 132 7 G Ahn W Chun Simulator for MPLS Path Restoration and Performance Evaluation Chungnam National University Korea 2001 pp 32 36 gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 8 9 10 11 12 13 14 15 16 MPLS Simulator http www entel upc es xavierh mpls 07 05 2007 G Ahn W Chun Design and Implementation of MPLS Network Simulator 15th International Conference on Information Networking 2001 pp 694 OpenSimMPLS http gitaca unex es opensimmpls 07 05 2007 http totem info ucl ac be index html 07 05 2007 http www opnet com 07 05 2007 S H Thomke Simulation learning and R amp D performance Evidence from automotive development Research Policy Volume 27 Issue 1 May 1998 pp 55 74 T J Overbye P W Sauer C M Marzinzik G Gross A user friendly simulation program for teaching power system operations IEEE Transactions on Power Systems Vol 10 Issue 4 Nov 1995 pp 1725 1733 T de Jong W R van Joolingen Scientific Discovery Learning with Computer Simulations of Conceptual Domains Review of Educational Research Vol 68 Issue 2 summer 1998 pp 179 201 A Parush H Hamm A Shtub Learning histories in simulation based teaching the effects on self learning and transfer Computers and Education Vol 39 Issue 4 Dec 2002 pp 319 332 Manuel Doming
4. e Scenes where is necessary the student interaction causing links failures or node congestions In the first case scenes will make the students to reinforce their theoretical concepts In the second point the students will analyze situations where although there is not network failures it performance can be improved by way of reconfiguring topology components or changing the profile of generated data flows In the last case the student will have the gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 6 opportunity to detect and to analyze the consequences of sporadic network failures The student will be able to check how the introduced variations affect to the final system performance 14 Theoretical concepts Knowledge 3 acquisition Obtaining conclusions pane nae Student means Obtaining Taking 3 conclusions decisions iri Dynamical scene designin i i RESUS Execution analysis Settings changes Evaluation Obtaining data a Operational statistics Fig 7 Double feedback process followed by the pupil when using OpenSimMPLS simulator OpenSimMPLS is an interactive application what means that the student becomes an active part during the simulation modifying properties of the scene in a dynamic manner developing this way the experimental knowledge and the discovery learning 15 16 Our tool is a solution to make the operation of an MPLS d
5. gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt l Educational improvements applying an MPLS network simulator a technical approach M Dom nguez Dorado F J Rodr guez P rez J Carmona Murillo J L Gonz lez S nchez Abstract Nowadays multiple services are being offered over the Internet next generation infrastructure Most of these services are causing important social changes online collaboration e commerce e vote knowledge sharing etc Future technical leaders should learn about the impact of their activities on the society and not only about the usual economic point of view These principles must be instilled into future engineers by their educators who should have a suitable set of teaching tools which allows them to improve their educational methods As MPLS is one of the most important technologies that support the integration of the aforementioned Internet services in this work we present an MPLS teaching tool and an evaluation of its influence when educating future engineers in an academic environment Index terms simulator MPLS teaching experience engineering education dynamical interaction networking tool I INTRODUCTION PLS Multiprotocol Label Switching is a connection oriented technology that arises to palliate the problems that current networks have related to speed scalability and traffic engineering 1 Simultaneously it offers end to end QoS
6. is the main area where simulation of different MPLS scenes takes place Main menu is located in the upper left corner It includes options related to file management creating saving and loading scenes to from disk windows layout and help Finally scenes windows allow designing and analyzing particular MPLS scenes Their structure is formed by several tabs which will be described in following sections A Topology designing area The first tab is the designing area in which the parameters related to the topology and configuration of the MPLS domain are set The toolbar is composed of several icons which show the elements that can be inserted in an MPLS domain LERs LSRs links The first icon makes reference to the Sender which is the node that generates network traffic in the simulator The second one is the Receiver which is the sink of this data flow The third one represents an LER Label Edge Router used to assign labels to IP or MPLS packets It also classifies them establishes a path towards the destination host through the MPLS domain and finally allows labeled packets to ingress in the MPLS domain The fourth icon is an LERA Label Edge Active Router that operates as an LER but it also analyses the IP header to know if packets have GoS requirements codifying in this case those requirements in the MPLS header 5 A GoS marked IP traffic can only keeps those GoS parameters inside the MPLS domain if this flow has a
7. task they are performing during their operation time Although the tick generation is a discrete process through its repetition we get a fluid simulation Therefore the elements of the topology gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 5 TNodoEmisor TNodoReceptor TNodoLER TNodoLSR TNodoLERA TNodoLSRA TEnlacelnterno TEnlace Externo will encapsulate methods to carry out these notification tasks The global events collector is implemented by TRecolectorSimulacion class This class has a method called capturarEventoSimulacion that allows the topology elements to send the simulation events generated during their threads execution time However the collector only gathers events but it doesn t show them To show them graphically the services of a simulation panel component must be used Thus the ability to isolate generation tasks and events gathering from its visual representation is achieved The simulation panel is implemented in JPanelSimulacion class that carries out tasks like screen refreshing visual simulating etc That is the events that arrive at the collector are interpreted and shown in the screen making easy the user understanding The method used to send the events to the screen is called ponerEvento A Scene s topology The topology is an object needed to store all the components in the scene and to manage the links graph between the nodes and the links
8. The use of OpenSimMPLS to carry out professional works in real network environments is not recommended due to its teaching purpose it doesn t incorporate real features of current manufacturers components However the present work proposes the use of OpenSimMPLS as an educational tool to be innovative when teaching subjects belonging to Telematics Engineering Area which is justified by the growing interest that the MPLS technology is waking up Also the simulator is a supporting tool to those research projects related to MPLS as a particular case we have implemented the GoS support on it as well as in teaching subjects related to this technology Particularly we have proved the improvement of the results concerning to Broadband communications group We observed an increase in the students motivation and interest with an improvement of the average mark and also obtaining more homogeneous qualifications as shown by the decrease of the standard deviation Its multiplatform philosophy and its free software license make easy its own evolution since it can incorporate the received feedback from other users by means of the project s homepage or via the simulator Contact the authors option Among its future possibilities we are thinking about carrying out coding practices so that the students of subjects related to Telematics Engineering Area can develop modules algorithms and additional network technologies on the simulat
9. ation of OpenSimMPLS the percentage of passed exams grows to 66 67 diminishing the rate of failed exams therefore to 33 33 100 80 41 18 60 20 2005 2006 2006 2007 I failed exams _ passed exams Fig 8 Comparative between pupils who have passed the exam and those who have failed it Years 2005 2006 and 2006 2007 gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 7 In Fig 9 are also observed that the groups average mark in 2005 2006 year was 4 67 on 10 and in 2006 2007 year that value ascended to 6 17 on 10 At the same time standard deviation diminishes from 3 19 points in 2005 2006 to 2 71 points in 2006 2007 showing therefore a better homogenization of students qualifications 2005 2006 2006 2007 E Average mark E Standard deviation of average mark Fig 9 Average grade variation and marks standard deviation for years 2005 2006 and 2006 2007 Summarizing in Fig 10 the improvement obtained in 2006 2007 year when using OpenSimMPLS is quantified on one hand the increment of the average mark has been 32 07 and on the other hand the decrease of standard deviation is 24 28 30 20 10 10 20 I Average Mark variation C Standard Deviation variation Fig 10 Increment of Average grade variation and decrement of marks standard deviation between years 2005 2006 and 2006 2007 VII CONCLUSIONS AND FUTURE WORK
10. ccessed through an LERA node Next icon represents an LSR which switches the traffic in the domain It is a fast component because it only checks packets label set by the ingress LER LERA An LSR node has not capabilities to be an MPLS gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 3 network edge router The sixth icon makes reference to an LSRA Label Switch Active Router that switches MPLS traffic inside the domain It also has the capability to perform packets retransmissions and LSP fails recoveries both in a local environment It also has the capability of temporary packets storing In this way it allows satisfying local retransmission requests from another LSRA in the domain Last icon is the Link which makes possible the connection between two nodes All components in a simulation scene have to be connected using links Traffic will flow through those links Anyway OpenSimMPLS incorporates errors control that allows the student to generate free of errors topologies B Scenes simulation area Once scene s topology design has been finished we should use the Simulation Area There one can analyze its behavior in a visual way traffic generation congestions link failures etc Fig 2 The simulation topology will be the corresponding to the scene specified in the designing area The only difference in the structure of both areas designing and simulation is the set of icons showe
11. d in the toolbar Now we can see icons to manage the simulation operation Finally we can start the simulation by clicking the first icon that shows a gear When a simulation is running a progress bar indicates the percentage of the simulation in course There is also a small counter at upper left corner that shows the number of elapsed simulation nanoseconds On the other hand it is also possible to slow the simulation what makes feasible to analyze simulation events in a more detailed way without the necessity of simulation stopping and restarting To do it one must use the slider in the toolbar Fig 2 Different types of traffic packets being discarded Real time simulation shown in the simulation area consists of the graphical representation of the internal values generated by the elements that compose the scene Most of times using both visual representation of the simulation events and statistical charts of the elements links and nodes is enough to understand the different events happened during the simulation however sometimes we need to have a numerical point of view to understand some complex situations To achieve it OpenSimMPLS is able to generate a human comprehensible trace file in text format containing all events that have taken place during the simulation for instance affected components consequences etc This way a functional method which makes possible to check the simulation is provided In order to gen
12. erate this trace file a click must be done on the checkbox called Create trace file During the simulation different scene elements automatically modify their visual appearance as needed For example LER and LSR nodes will change their color depending on their congestion level This is a measurement of the amount of packets accumulated in the node buffer Graphical representation of packets will allow knowing the kind of on fly data traffic in the simulation window classified according to their priority It also informs about the quantity and types of traffics flows speed when and how the signaling takes place established paths etc Normally packets are forwarded through the network but they also can be discarded in congested nodes In this case packets will be shown graphically falling down these nodes Fig 2 During simulation packets representation belonging to different types of traffic as well as data flows forwarding can be analyzed with the aid of the legend that is shown optionally at the lower right corner Fig 3 The legend has demonstrated to be a great help to the students when they use OpenSimMPLS they are able to analyze what is happening during simulations 4 Facket recejved a Packet generated Packet sent Ef Packet switched Soe Le Backup LSP F packet o IF G05 packet a MPLS packet ad MPLS Gos packet TLOP packet OPSRP packet TS Fig 3 Visual help to be used by t
13. hanism has been provided to take advantage of present infrastructure in backbone environments making easy the migration between technologies however the efforts performed for years to develop innovative mechanisms that offer support to IP over ATM have not been lost Most of the developed techniques are still valid to have IP over MPLS and MPLS over ATM E open simmpcs robo yea pep FF pacha loa Darkest 8 iF fl T aL packer T pL pets picur a TLOP piigi GREP paika Fig 1 General view of a scene window where flows with different GoS levels coexist In this work we show up an MPLS network simulator called OpenSimMPLS It is a functional and visual tool Fig 1 that can be used in network and or communications teaching It considers the main operational and setting aspects of an MPLS domain 4 at the same time it has been improved to be compatible with GoS supporting Guarantee of Service domains 5 An MPLS domain with GoS capability could be understood as an environment able to carry out local recoveries of discarded MPLS packets together with the possibility of re establishing LSPs Label Switched Paths in a local way 6 7 This feature can be offered to some specific and privileged flows that needs a fast and reliable service GoS also allows these flows to be prioritized with regard to those not characterized as GoS traffic In the following section a comparative between some common teaching simulators i
14. he pupil during the simulation At this moment we have explained several visual signs that have to be interpreted to understand the events that take place during a simulation However simulation is an interactive environment and lots of actions can be issued For instance node congestion can be caused by clicking on the node After that the node will suffer great packets saturation Fig 4 If it continues receiving incoming traffic surely will begin to discard packets in a short time This function is very useful to cause packets losses and consequent packets retransmissions without having to wait the natural node congestion Fig 4 Artificial congestion of nodes In real conditions a link has failure possibilities Repairs electric discharges human mistakes etc can make a link to fail and then its traffic will be discarded However traffic overload does not cause a link failure OpenSimMPLS can simulate that fact because it supports link failures anytime However it is not an event that happens during the simulation in a natural way so it must be caused by hand We will be able to simulate a link failure in a simulation with a click on the desired link The link will change its appearance showing gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 4 itself as a dashed red line and will cause all on fly packets to be lost C Analysis of results area We can go on to use the Analy
15. ks duration The clock which is executed into its own thread will advance from the beginning until it reaches the maximum number of ticks defined for the overall simulation Every tick will be sent to all scene elements which are synchronized so when it reaches the end the thread will be stopped and the simulation will finish When the different topology components receive a tick they also get its duration number of nanoseconds Then every component activates its own execution thread so it is generating concurrent processes Each thread will carry out a task depending on the device type for instance switching packets forwarding etc Each component execution thread will stop when the time conferred on it by the received tick is used up rri Po 4 f amp t f i i i Links and nodes Simulation events Events collector Simulation panel Fig 6 General operation of a scene simulation When every component has used their tick up the clock detects it and generates the next tick to repeat again the process The class that implements the clock is denominated TReloj and contains an internal list of elements Every elements belonging to that list will get temporization events by the clock At runtime lots of events happen They must be collected in order to shown them in a visual form This acquirement process is carried out by a scene global collector All topology elements will notify the collector of the
16. n changes e Simulation allows the student to obtain detailed statistical data that can be used to examine particular behaviors of the MPLS domain e It is open source software That means that it allows the educators to teach not only networking subjects but also coding subjects proposing to their students some changes to be implemented to the simulator in order to improve it or add new capabilities VI REAL OPENSIMMPLS EVALUATION IN THE UNIVERSITY In our case the simulator is used to gain teaching innovation in subjects belonging to the Telematics Engineering Area at Polytechnic School of Caceres such as Broadband communications or Network planning specification designing and evaluation It is also used in subjects focused to train Ph D candidates e g Multimedia multiprotocol and heterogeneous networks integration with QoS and Broadband multimedia and _ multiprotocol communications with QoS and security at the University of Extremadura We have carried out a comparative study of the OpenSimMPLS use in Broadband communications The study compares the qualifications obtained by the students in 2005 2006 academic year teaching without the use of OpenSimMPLS and 2006 2007 academic year when we used the simulator as a supporting tool In Fig 8 it can be observed that for 2005 2006 year the rate of passed exams was 58 82 and 41 18 of failed exams In the following year coinciding with the incorpor
17. omain familiar to students of networking subjects The student can research into communications issues and size up MPLS network resources avoiding unnecessary risks of modifying the configuration of real devices in the lab local network On the other hand and as collateral goal the statistical results obtained will be useful to the student to develop new methodologies in its future work as next generation network planner It allows acquiring a very methodical discipline planning of a MPLS network obtaining and analyzing results and successive refinements toward a final optimal architecture Fig 7 The use of OpenSimMPLS reinforces the theoretical concepts of MPLS technology and offers the students the motivation they need to understand the interaction between different components of a scene To sum up using the simulator as a teaching support to explain MPLS operation contributes several advantages e tis easy to install in a lab it doesn t require database it admits multiple architectures and operating systems e The use of the simulator as a teaching or a learning validation tool will always suppose a cheaper solution than deploying a real MPLS domain in an academic laboratory e OpenSimMPLS allows modifying the settings of the scenes components after that it let us to analyze the consequences of these changes and to learn of them In a real MPLS network at an academic lab won t always be allowed to carry out configuratio
18. or On the other hand OpenSimMPLS will be improved by adding IPv6 Internet Protocol version 6 and RSVP Resource Reservation Protocol support and with the addition of new visual features intended to allow obtaining a more detailed and richer information ACKNOWLEDGEMENTS This research work is sponsored in part by the regional Education Science and Technology ministry belonging to the Extremadura Regional Government by means of AGILA project numbered as 2PRO3A090 REFERENCES 1 M Kodialam T V Lakshman Restorable Dynamic QoS Routing IEEE Communications Magazine Vol 40 Issue 6 June 2002 pp 72 81 2 J Gozdecki A Jajszczyk R Stankiewicz Quality of Service Terminology in IP Networks IEEE Communications Magazine Vol 41 Issue 3 Mar 2003 pp 153 159 3 E Rosen et al Multiprotocol Label Switching Architecture RFC 3031 January 2001 4 M Dominguez Dorado F J Rodriguez P rez J L Gonzalez Sanchez A Gazo Multiplatform and Opensource GoS MPLS Simulator II European Modelling and Simulation Symposium EMSS2006 International Mediterranean Modelling Multiconference I3M2006 Barcelona 2006 pp 529 537 5 F J Rodriguez P rez J L Gonzalez Sanchez A Gazo Cervero RSVP TE extensions to provide guarantee of service to MPLS IFIP Networking 2007 Atlanta USA May 2007 6 J L Marzo E Calle C Scoglio T Anjali QoS Online Routing and MPLS Multilevel Protection A Survey IEEE Communications
19. quire any difficult step and we just only need to invoke OpenSimMPLS execution through the SUN s Java Virtual Machine that should have been previously installed One of the OpenSimMPLS advantages is its portability since it works independently of computer architectures or operating systems That is why Java language has been used Java has also allowed the implementation of the simulator as a multitask application it is able to simulate more than a scene simultaneously what is gotten by means of multithreading coding Moreover Java is an object oriented language The simulator s main class called openSimMPLS starts the simulator execution The main method belonging to that class creates a TDispensadorDelmagenes object that will load all necessary images for the application Then it will be passed as a parameter to the constructor of every interface elements improving the performance Later a JSimulador object is created It is the main application window At this moment simulation execution gives up being a sequential process From that moment everything is controlled by listening to the user events generated by the application interface mouse orders menu options etc During the simulation a clock sends signals to the scene elements links and nodes as temporization events Fig 6 or ticks The clock component is configured using two values first the simulation length total number of ticks and second the tic
20. r hand it doesn t allow interacting with the simulation at runtime or changing its language Also due to its educational approach it has not been designed to work in real MPLS networks using current manufacturers components MNS MPLS Network Simulator 9 is an NS2 Network Simulator 2 extension to allow MPLS networks simulations Therefore their features are similar to those of NS2 that is it is a teaching tool allows a full statistical analysis of all the events happened during the simulation it is multiplatform software it is distributed under the terms of a free software license and it is free of charge Some of its weaknesses are it doesn t allow the user to interact at simulation time to modify its behavior that is the simulation will operate as previously specified in the configuration file In teaching tasks this static behavior prevents the student to exploit the discovery learning mechanism The installation of MNS NS2 is not easy it requires to compile and to install some libraries The generation of simulation scenes is difficult due to the necessity of knowing TCL Tool Command Language for the definition of scenes and all their components This last confers to MNS NS2 the property of being a complete tool to validate research results but in teaching tasks it originates a learning curve that makes difficult the design of practical sessions in a short time This is a great problem taking into account the difficul
21. ration otherwise the default simulator language will be English OpenSimMPLS uses the Java internationalization system so it is easy to translate the tool to another language It also has an easy to use graphical interface Each element is coded following the object oriented paradigm and the generated processes operate by means of independent threads in a concurrent way The simulation is composed by three stages MPLS domain design and configuration visual representation of events and generation of simulation statistical results Students of networking and communications subjects increase their learning thanks to practical examples The simulator permits the students to observe the network behavior in particular situations for instance when the kind of used traffic is multimedia It also allows comparing and contrasting the results thanks to the reconfiguration of domain elements In this way students can improve MPLS scenes proposing new features to be added It is also possible to detect either pernicious or beneficial effects on the traffic A discovery learning based method is performed in OpenSimMPLS so students can solve their own problems and situations learn technology procedures and understand events features They also learn how to control these events and what to do in particular cases thanks to the dynamical interactivity during the simulation OpenSimMPLS can be used to help students to reinforce their knowledge abou
22. s made In third section a brief description of the simulator visual environment is shown as well as some other functional aspects In fourth section we explain some important technical issues about its implementation In fifth point the applications of OpenSimMPLS in academics environments or preliminary research works are highlighted In section six we show recent results obtained after using the simulator to teach future gt REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER DOUBLE CLICK HERE TO EDIT lt 2 engineers Finally the article concludes summarizing the contributions of the simulator and the future work II RELATED WORK OpenSimMPLS is not the first effort carried out to develop an educational MPLS simulator Some researchers have already made proposals in this way For example in 8 we can find an MPLS simulator that allows designing and setting MPLS domains and their components One can run a simulation and perform statistical analysis of its results everything from an educational point of view Their main features are it is a teaching simulator that allows an elementary statistical analysis of the network traffic it has a visual editor to design scenes it is a multiplatform software and although of facto it is free of charge and easy to install it is an runnable applet located at project s homepage neither its source code is available nor it is a downloadable executable for a local execution On the othe
23. sis Area Fig 5 if we have set scene s components to generate statistical data then we will see the charts that they are generating or that they have already generated if simulation has finished E Open SimmPLs Scene Yiew Help 3 A EfectoDeRABAN osm Design KC Simulation 32 Analysis a Options f em Select an element to show its statistics C LSRA 1 w parcor Brows Ty a M L E Outgoing packets n ps w me uv oO Qa o as w a 3 zZ 50 000 100 000 150 000 200 000 250 000 300 000 350 000 400 000 450 000 Time ns JM TLDP mi MPLS GoS 1 W MPLS GoS 3 MPLS Fig 5 Chart example Analysis area This area is split up in two parts a toolbar where we can choose the node or link to be analyzed and a bigger area where the statistical charts will be shown During a simulation charts will have a dynamic behavior changing according to the simulation advances If it has already finished charts show final results Furthermore charts generated by OpenSimMPLS are not static images but they operate as interactive objects One can obtain a pop up menu just clicking on a chart using the secondary mouse button This way one will have access to different options for instance disk saving of the image interesting chart enlargement or printing etc IV IMPLEMENTATION DETAILS OpenSimMPLS is a standalone JAR application Installation therefore does not re
24. t the technology for instance when the students think in a hypothetical network situation they can test it through the simulator results In this way the simulator is a test bed that returns feedback to the students Fig 7 This returned information must be analyzed to know what happens inside the MPSL domain and how it is operating In summary there is a double feedback process when the simulator is used in an academic centre In one hand the simulator execution gives the student the possibility of analyzing the MPLS scene behavior in the other hand after examining statistical results several conclusions can be inferred by the student who will can change the settings and restart the simulation This repetitive process motivates the students to develop their own mental strategy about MPLS operation Hereafter we show the educational OpenSimMPLS capabilities as well as guidelines for using it in a lab practical session First of all the teacher explains the theoretical concepts about MPLS technology as well as their possible problems nodes congestion links failures packets loss etc Next the student can immediately start the practical session Wasting time on explaining the simulator operation is not necessary due to the useful user manual that it enclose In practical sessions several activities will be proposed to the students e Well designed and optimum MPLS scenes e Scenes where exist common problematic situations
25. ty of fitting these practical sessions into a teaching calendar at universities As the previous simulator it is not capable to work in real MPLS networks Although it is broadly used in teaching it is focused on networks research works In the case of OpenSimMPLS 10 in order to make easy its future use in different academic organizations it has been developed as multiplatform software licensed under the terms of GPL General Public License It incorporates the advantages of 8 and 9 but it also allows students to dynamically interact with the simulation it is translated to other languages allows visual designing of scenes and GoS technology simulation it doesn t require installation A comparison between the features of these three simulators is presented in Table 1 In order to do more specific works not educational there are more complete tools for instance Totem 11 or OPNET 12 both directed to work in real environments TABLE 1 SIMULATORS COMPARISON Ae Pan ODS Ere Teaching tool e e Interactive simulation e Statistics data e e Multiplatform e e e Multilanguage Visual design e e Free software e e Free of charge e e e GoS simulation e Real environments applicability Installation and i execution easiness HI OPENSIMMPLS SIMULATOR Simplicity is the main feature of the simulator s graphics user interface It has tree differentiated areas workspace main menu and scenes windows The first one
26. uez Dorado Zafra Badajoz Spain 1977 He got his BS and MS degree in Computer Science at University of Extremadura 2004 Now he is a Ph D candidate and FPI grant holder at Telematics Engineering Area Computing Systems and Telematics Engineering Department UEx His areas of interest are MPLS TE QoS routing and inter domain routing Fco Javier Rodriguez P rez Huelva Spain 1976 He got his MS degree in Computer Science at University of Extremadura 2000 Now he is professor at Telematics Engineering Area Computing Systems and Telematics Engineering Department UEx His areas of interest are QoS routing and Guarantee of Service over MPLS TE Javier Carmona Murillo Badajoz Spain 1982 He got his BS and MS degree in Computer Science at University of Extremadura 2005 Now he is a Ph D candidate and a researcher at Telematics Engineering Area Computing Systems and Telematics Engineering Department UEx His areas of interest are QoS and IPv6 mobility support Jos Luis Gonzalez Sanchez He got his Ph D in Computer Science at Technical University of Catalonia He is Lecturer Professor and Telematics Engineering Area coordinator at Computing Systems and Telematics Engineering Department UEx He is the main researcher of GITACA research group His areas of interest are QoS MPLS TE and security in communications 8
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