* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CS 5865
Survey
Document related concepts
Asynchronous Transfer Mode wikipedia , lookup
Wake-on-LAN wikipedia , lookup
Piggybacking (Internet access) wikipedia , lookup
Computer network wikipedia , lookup
Zero-configuration networking wikipedia , lookup
Deep packet inspection wikipedia , lookup
Distributed firewall wikipedia , lookup
Cracking of wireless networks wikipedia , lookup
Airborne Networking wikipedia , lookup
List of wireless community networks by region wikipedia , lookup
Transcript
Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed Chaudhry Usman Ali UNB, Fredericton TESTING SIMULATOR ACCURACY • Measure real network traffic. • Compare real network traffic with the simulator results. Real Traffic Types of Traffic: CBR (Constant Bit Rate) data traffic. (Simplicity) FTP (File Transfer Protocol) session. (Popularity and Dynamic behaviour) Simulated Traffic CBR (Few external factors influence the model) FTP(Complex) HTTP(too many degrees of freedom) METHODS OF SIMULATION Discrete Event Analytical Simulation Produce predictions in the network at a low level (packetby-packet). Use mathematical models to produce their results. Accurate. Sacrifice Accuracy ! But SLOW ! Faster speed ! NS-2 and OPNET use a hybrid approach. SIMULATION TOOLS • OPNET MODELLER • NS-2 1. 2. 3. 4. 1. Finite State Machine + Analytical Model. 2. 400 special purpose modelling functions. 3. Not open source. 4. Model parameters can be altered. Numerous models of Internet protocols. C++ : per packet processing. Otcl : Simulation Scenario NAM network animator. generation. Animations and graphs. Custom applications and protocols can be created. NETWORK TESTBED 5 PCs. Client-Server Pair. G- Traffic Generator. S - Traffic Sink. Hub 10/100 Mbit links. * KURT G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. NETWORK REPRESENTATION OPNET NS-2 G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. EXPERIMENTS CBR Traffic 1. Characterized by a fixed bandwidth across the network. 2. Typically used by applications such as video and audio. 3. CBR traffic stream can be generated by fixing the packet size and using the same interarrival time between packets. FTP Session Share, transfer and transmit information between two computers. Two types of test were performed for the FTP experiments. 1- FTP sessions using default settings. 2- Finely tuned FTP parameters. PARAMETER TUNING Reno to New Reno Fast Recovery capability + recover without retransmission. Window Scaling Allows advertisement of window sizes bigger than 65 kB. Timestamp Imitates the echoing capability of the testbed in both directions. Link Latency Affects RTT. Max Segment Size Bigger Ethernet packets. Window Size More range for sliding the window value. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for PacketLevel Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. TRAFFIC SCENARIOS IP Traffic monitored using tcpdump. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. RESULTS Scenario# Client –Server Load Traffic G. – Traffic S. Load CBR1 2 Mb/s 0 Mb/s ROUTER`s PERSPECTIVE NS-2 displays a more realistic CBR behaviour. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. Scenario# Client –Server Load Traffic G. – Traffic S. Load CBR2 2 Mb/s 2 Mb/s CBR3 5 Mb/s 0 Mb/s ROUTER`s PERSPECTIVE Lower throughput for the network testbed. Scheduling problems? G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. Scenario# Client –Server Load Traffic G. – Traffic S. Load CBR4 5 Mb/s 6 Mb/s CLIENT`s PERSPECTIVE Sudden drop SERVER`s PERSPECTIVE ROUTER`s PERSPECTIVE Scenario# Client –Server Load Traffic G. – Traffic S. Load FTP1 10 MB File 0 Mb/s (CBR) FTP3 10 MB File 0 Mb/s (CBR) ROUTER`s PERSPECTIVE Server to Client Client to Server Without tuning. With tuning. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. Scenario# Client –Server Load Traffic G. – Traffic S. Load FTP2 10 MB File 6 Mb/s (CBR) FTP4 10 MB File 6 Mb/s (CBR) ROUTER`s PERSPECTIVE Server to Client Client to Server Without tuning. With tuning. G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003. Conclusions • Pure CBR type traffic. (NS-2 performed better). • In one scenario OPNET performed “better”. • FTP Experiments • NS-2 FTP simulation model only indicated general transfer rate rather than replicating the actual network flow. • OPNET performed closely to the testbed results. • Simulation speed was fast in both simulators. • The learning curve was different and steep at times. • NS-2: “script” generated. • OPNET: User Interface. Conclusions Contd.. • In FTP session, simulators did not model the dynamic behaviour of FTP in standard form. • FTP adapts its output to prevailing network conditions. • NS-2 and OPNET did not always mimic this performance. • However, OPNET performed better. Future Work • Establishing a scheme to model HTTP in the simulators and the testbed. REFERENCE • G. Flores-Lucio, M. Paredes-Farrera, E. Jammeh, M. Fleury, and M. Reed, OPNET-Modeler and NS-2: "Comparing the Accuracy of Network Simulators for Packet-Level Analysis using a Network Testbed". 3rd WEAS Int. Conf. on Simulation, Modelling and Optimization (ICOSMO 2003), Crete, vol. 2, pp. 700-707, 2003.