Modeler Day 3 Modeler Day 3 1 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Course Content DAY 3: DAY 4: • Configuring Standard Applications {LABs} • Traffic Modeling Techniques {LABs} • Modeling Large Networks • Process Modeling Methodology • Accelerating Wireless Simulations{LABs} • Custom Wireless Effect {LABs} • Importing Topology and Traffic • Debugging Simulation Models{LABs} 2 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Standard Applications 3 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: application demands • Troubleshooting • Lab 4: troubleshooting (bonus) 4 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Take-Away Points • Standard applications available • Application configuration • Defining user profile • Client & server setup for standard applications • Application demands • Application modeling techniques • Application troubleshooting 5 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: application demands • Troubleshooting • Lab 4: troubleshooting (bonus) 6 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 How Do We Define Network Traffic? • Source (user, group of users) • Destination (user, server) • Traffic patterns 7 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Applications REQUEST • Client-server applications RESPONSE • Examples: HTTP, FTP REQUEST RESPONSE • Peer-peer applications REQUEST RESPONSE • Examples: voice, video • Multi-tier applications 1 REQUEST 2 REQUEST 3 4 RESPONSE RESPONSE • Examples: web-based applications, e-commerce, home-grown applications 8 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Modeling Techniques • Explicit • Simulate all packets in detail • Very high fidelity results • Potentially longer run times • Analytical • Simulate majority of traffic using mathematical representation • Faster simulation run times • Hybrid • Combination of both explicit and analytical modeling techniques 9 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 OPNET Application Architecture Profiles Describe user behaviour Applications Define application configuration Tasks Describe basic unit of user activity Custom application Phases Define communication patterns within each task 10 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profile and Applications: Example Profiles Apps Engineer HTTP FTP Marketing Department Video HTTP Sales Engineer Voice Database 11 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Application Models: Workflow Configure applications Define profiles Configure servers/peers Deploy profiles 12 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: AppDemands • Troubleshooting • Lab 4: troubleshooting (bonus) 13 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Applications Configure applications Define profiles Configure servers/peers Deploy profiles 14 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configure Applications 15 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Applications: Built-in Common Applications Standard applications Name Description Custom Application Generic/customizable application Database Data entry/query application E-mail E-mail application FTP File transfer protocol application HTTP Web-browsing application Print Print job Remote Login Telnet application application Video Conferencing Client-to-client video application Voice Client-to-client voice application 16 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Applications • Session of specific request/response patterns • Commonly used applications: email, http, ftp… • Common settings to all applications • Type of service • Symbolic server name • RSVP parameters • Specific settings to each application • HTTP page configurations • FTP file sizes • Database query ratio 17 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Definition Utility • Contains all application definitions “FTP (Light)” Application Definition • Reusability • Across clients • Across scenarios • Easier deployment • Easier change I’m running I “FTP (Light)” I’m running I “FTP (Light)” I’m running “FTP I(Light)” I’m running I “FTP (Light)” I’m running I “FTP (Light)” I’m running “FTP I(Light)” 18 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Symbolic Server Name Application has a symbolic server name, e.g. “FTP (Light)” Mapping between symbolic server name and actual server name Actual server name is specified in server, e.g. WashingtonDC_Server 19 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Definition Object 20 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Example: File Transfer Protocol • Upload or download of files: • Using file size distribution • Using Inter-request time distribution FTP (Application) PUT GET PUT InterRequest Time InterRequest Time PUT time InterRequest Time Specific FTP settings Common settings 21 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Example: Hypertext Transfer Protocol (HTTP) • Download of a web page: • Using distribution for number of objects in page and sizes • Using page interarrival time distribution HTTP (Application) Web page download Page Inter arrival Time Web page download Web page download time Page Inter arrival Time Specific HTTP settings Common settings 22 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Hypertext Transfer Protocol (cont.) 23 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profiles Configure applications Define profiles Configure servers/peers Deploy profiles 24 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Define Profiles 25 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profiles • Profile = Reusable collection of applications • Describes activity patterns of: • an individual user • a group of users Engineer Engineer Engineer CFO Marketing department CEO Help desk 26 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profile Configuration Object • Contains all profile definitions • Reusability • Across clients • Across scenarios • Easier deployment • Easier change Engineer Profile Definition I’m an I engineer I’m an I engineer I’m an I engineer I’m an I engineer I’m an I engineer I’m an I engineer 27 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profile Properties Repeatability Profile Name Operation Mode Applications Duration Start Time 28 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profile Name, Start Time, and Duration • Example: • “Engineer” profile • Starting at 9:00am • Lasting 8 hours Duration Engineer 9:00am 12:00pm 5:00pm Start Time 29 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Profile Repeatability • Serial mode Engineer Engineer Inter-repetition time Engineer Inter-repetition time Engineer Inter-repetition time • Concurrent mode Engineer Engineer Inter-repetition time Engineer Inter-repetition time Engineer Inter-repetition time 30 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Applications in Profile I have the definitions of the following applications: • Database Access (Light) • Email (Light) • Web Browsing (Light) • FTP 31 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Scheduling • Multiple applications per profile “Engineer” profile Database Web Browsing Web Browsing Web Browsing Email FTP 9:00am FTP FTP FTP 12:00pm FTP 17:00pm 32 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Operation Mode • Simultaneous Database Web Browsing Email FTP 9:00am 12:00pm 17:00pm • Serial (ordered/random) Database 9:00am Web Browsing Email 12:00pm FTP 17:00pm 33 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Applications in Profile Repeatability Name Start Time Offset Duration 34 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Name, Start Time Offset, and Duration • Example: • “FTP” application • Starting 2 hours after profile “Engineer” starts • Lasting 4 hours Engineer (Profile) FTP (Application) PUT Start time offset 9:00am PUT GET PUT Duration 11:00am 3:00pm 5:00pm Note: an application will not last longer than the profile 35 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Repeatability • Serial mode FTP FTP Inter-repetition time FTP Inter-repetition time FTP Inter-repetition time • Concurrent mode FTP FTP Inter-repetition time FTP Inter-repetition time FTP Inter-repetition time Note: an application will not repeat and last longer than the profile 36 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configure Servers/Peers Configure applications Define profiles Configure servers/peers Deploy profiles 37 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configure Server/Peers (cont.) 38 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Server Supported Service Setup 39 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Server CPU Setup 40 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Server Address • Uniquely identifies server • Server address to be mapped to the symbolic server name 41 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Deploy Profiles Configure applications Define profiles Configure servers/peers Deploy profiles 42 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Deploy Profiles (cont.) 43 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Client Profile Setup 44 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Destination Preferences • No destination preference => Randomly select among destinations supporting service • Selection weight set on destinations My weight is 10 Choose me! Server2 is 5X more likely to be chosen Client Server1 ? My weight is 50 Choose me! Server2 Explicitly configure destination(s) => Randomly select among destinations specified on client Weight set on client I have to choose between: - Server1: weight 20 - Server2: weight 10 Client ? Server1 is 2X more likely to be chosen Server1 Server2 45 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Destination Preferences Application refers to a symbolic server name, e.g. web_browsing_server Mapping between symbolic server name and actual server name Actual server name is specified in server, e.g. WashingtonDC_Server 46 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Destination Preferences (cont.) 47 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Statistics • Local and global statistics • Client/Server statistics or calling/called party statistics • Specific to each application • Local statistic results will be grouped per profile/application 48 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab 1: OPNK2003 Cyber Cafe • Objective • Apply workflow to configure application traffic • Application configuration • User behavior profiles • Configure servers to support applications • Deploy user profiles Configure applications Define profiles Configure servers/peers Deploy profiles • Refer to lab handout “Lab1: HTTP Application Configuration Lab” on page 1 49 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: AppDemands • Troubleshooting • Lab 4: troubleshooting 50 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Analytical Traffic on Voice and Video Applications • Voice and video: intensive discrete-event applications • Streaming applications • Each small packet is modeled • Long simulation run • Not scalable • Solution to improve simulation performances • Analytical traffic • Interpret all traffic as a background traffic flow • Loss of accuracy • Hybrid traffic • Model part of the discrete traffic in an analytical flow • Keep accurate response time and jitter • Still model specific internals of voice application 51 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Hybrid Traffic Concept Discrete event traffic Analytical traffic Hybrid traffic 52 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 VoIP “Traffic Mix” Attribute 53 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Video Conferencing “Traffic Mix” Attribute 54 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Methodology • Configure most of your VoIP or video nodes with background traffic • Configure the node of interest to use discrete traffic 55 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab2: Configuring VoIP • Objective • Apply hybrid traffic to generate VoIP traffic and get end-to-end delay • Refer to lab handout “Lab2: VoIP Application Configuration Lab” on page 26 56 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: AppDemands • Troubleshooting • Lab 4: troubleshooting (bonus) 57 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Definition • Abstract of a client-server or client-client application • Connects two end-nodes • Request/response oriented configuration • Available in “applications” object palette • Advantages • • • • Configuration friendly Custom-made traffic Possibility to use discrete, hybrid, or analytical traffic Visual representation of the application flows • Limitations • No specific internals of a standard application • Only for simple traffic patterns 58 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Concepts Requests Client or server Client or server Responses Rate (requests/hour) Start Time End Time Time 59 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Deployment • Click and connect • No need for configuration objects • Right-click on demand to configure • Demands can be copied and pasted for duplication 60 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Attributes • Generic traffic configuration • Duration • Request parameters • Response parameters • Hybrid traffic • Transport protocol 61 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Deployment Wizard • Faster deployment to create application demands • Full mesh • From one node to many nodes • From many nodes to one node • Note: • If 2 or more nodes are selected before starting wizard, configuration applies to selected nodes only • If no node is selected before starting wizard, configuration applies to all nodes in network 62 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Application Demand Statistics • Statistics per demand collected on end-nodes • Traffic sent/received • Response time • No global statistics 63 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab3: Deploying Application Demands • Objective • Generate traffic quickly using Application Demands • Please refer to lab handout “Application Demand Configuration Lab” 64 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Application basics • • • • Network traffic (users, devices, networks, etc.) Modeling traffic in OPNET Application modeling techniques OPNET application architecture • Configuring applications workflow • • • • • Configure applications Define profiles Configure server/peer Deploy profiles Lab 1: OPNK2003 cyber café • Configuring analytical traffic on client-client applications • Concepts and attributes • Lab 2: VoIP configuration • Easy configuration of application traffic • Concepts and attributes • Lab 3: AppDemands • Troubleshooting • Lab 4: troubleshooting (bonus) 65 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Troubleshooting Guidelines • «I don't see any traffic» or «I don't see expected traffic» • • • Check simulation logs Look at the “Common problems” section of this presentation Use constant distributions to make profile scheduling deterministic • Collect application Traffic Sent/Received stats in “All Values” mode • Shows exact size and time data was sent Make sure this is not a network issue • Connect an application demand between your client and server • See if you get application demand response time statistics • • • • Scale down the network • Isolate the problem Use “User Defined Reports” in “Scenarios” menu • Globally visualize attribute settings Use “Network Difference Report” in “Scenarios” menu • Compare to a similar working scenario 66 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Troubleshooting: Simulation Logs • Simulation = first place to look at • Available in “DES” menu 67 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Troubleshooting: Simulation Logs (cont.) Profile won't repeat if profile duration is equal to simulation duration. Simulation “Engineer” profile “Engineer” profile In serial mode, an application will not start if previous application duration is equal to profile duration. Simulation “Engineer” profile “FTP” application “HTTP” application 68 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Troubleshooting: Simulation Logs (cont.) • Profile set on a client doesn't exist Sorry, I don’t know what an engineer is. I’m an engineer ? “Engineer” profile Service set on server doesn't exist Sorry, I don’t know what “FTP (Light)” is. ? I’m running “FTP (Light)” “FTP (Light)” application 69 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Troubleshooting: Simulation Logs (cont.) Service set on server doesn't exist Sorry, I don’t know what “FTP (Light)” is. ? Profile “engineer” uses “FTP (Light)” • All required application parameters are not configured “FTP (Light)” is a FTP application Sorry, I need more information to use “FTP (Light)”: • File size • Inter-request time 70 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Common Problems ‘Profile start time + application start time offset’ protocols and spanning tree algorithm etc’ I want to send this FTP packet < ‘Convergence time of routing Wait, I don’t have a route to the server yet ‘Profile start time + application start time offset’ > ‘Simulation end time’ Common when using exponential distribution with start time and/or start time offset Simulation Profile start time Simulation “Engineer” profile Profile start time Application start time offset 71 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Common Problems (cont.) If application duration is longer than profile duration, application will be terminated when profile is over. Simulation “Engineer” profile “FTP” application The symbol map “Unlimited” for profile and application “Repeatability” has a default interarrival time of 300 secs by default. “Engineer” profile “Engineer” profile 300 secs “Engineer” profile 300 secs “Engineer” profile Etc… 300 secs 72 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Common Problems (cont.) Voice and video conferencing can be configured between two clients/LANs only. wrong Voice/Video Applications other than voice and video conferencing can be configured between a client/LAN and a server/LAN only. wrong FTP, email, database, http, remote login, print 73 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Advanced Troubleshooting • Run OPNET debugger (ODB) • Diagnostic traces • Per application type: “ltrace gna_<application_type_name>” Examples: “ltrace gna_email”, “ltrace gna_ftp”, “ltrace gna_http” • For all applications: “ltrace gna” • Simple example • Start simulation under ODB • ODB> ltrace gna • ODB> cont • This is an advanced technique. For more details, see session 1502: Debugging Simulation Models — Introduction 74 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab4: Troubleshooting • Objective • Learn how to troubleshoot an application setup • Please refer to lab handout “Application Troubleshooting Lab” 75 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Configuring Custom Application: Workflow Break down the application Configure tasks Configure custom app Define Profiles Configure tiers Deploy profiles 76 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Breakdown of the Application • Identify the tiers For example, an online e-commerce application might involve • Client • Web server • Authentication server • Database server 77 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Summary • Standard applications available • Profile configuration • Application configuration • Client & server setup for standard applications • Application demands • Application modeling techniques • Troubleshooting 78 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Traffic Modeling Techniques 79 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation 80 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Motivation • It is critical to provide good inputs (garbage in → garbage out) • network topology • traffic • It is equally critical to choose a traffic modeling technique • simulation speed vs. accuracy • This session focuses on modeling traffic 81 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation • Lab #3 • Flow Analysis 82 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Real-world Traffic Representation • Types of traffic • WAN, LAN, application traffic • Traffic representation in OPNET Traffic Type OPNET Representation Packet by Packet Explicit Traffic Aggregated Traffic Traffic Flows, Device/Link Loads (Background Traffic) • Choice of representation depends on modeling purpose • Packet by packet • End-to-end delays, protocol details, segmentation effects • Aggregated traffic • Capacity planning, steady-state routing analysis 83 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Parameters in Traffic Representation • Traffic Parameters File Size Interarrival time • Packet inter-arrival time or arrival rate • seconds, packets/second • Packet size • bits, bytes etc. • bits/sec = bits/pkt * pkts/sec • Variability settings • Probability Distribution Function (PDF) • standard (exponential, bernoulli etc) • custom • build your own with PDF editor • scripted 84 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation 85 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Sources of Explicit Traffic • Explicit traffic injected at • Application Layer • email, HTTP, FTP etc • ACE, app_demands • Network Layer • RPG (self-similar traffic generator) • Lower layers • Native protocol sources • Ethernet, ATM, Frame Relay etc 86 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Sources of Aggregated Traffic • Traffic flows injected at • Application Layer • app_demands • Network Layer app_demand • IP traffic flows • Lower Layers • ATM traffic flows IP Traffic Flow • Element loads • CPU utilization • Link loads • Do not require source models 87 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Traffic Data Import Traffic Data Network monitoring software samples traffic periodically using probes Export to text files or OPNET recognizable formats Import into OPNET 88 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing Explicit Traffic – Packet Trace • Packet traces captured using network analyzer • Sniffer analyzer • tcpdump • windump • Application Characterization Editor (ACE) 89 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing Server Data • Import from • HP OpenView Performance Agent • BMC Patrol • Concord SysEDGE • NetIQ AppManager • Generic XML • Server Characterization Editor (SCE) 90 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing Aggregated Traffic – Flow Data • Flow-specific data • Demand objects 91 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing Aggregated Traffic – Link Loads • Link load information from • Concord NetworkHealth • MRTG • Spreadsheet (text info) • Can be converted into traffic flows 92 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation 93 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Simulation Techniques • Discrete event simulation • Model all traffic (data, signaling, management) using packets • Account for all timers in every protocol layer • Perform every state/event transitions of all protocol layers • Analytical simulation • Abstract queue performance using mathematical equations • Model traffic as state information in various network elements • Hybrid simulation • Mix of modeling approaches (discrete event + analytical) • Mixture of traffic types (explicit traffic + aggregated traffic) 94 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Comparison of Various Simulation Techniques 95 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Examples of Analytical Methods Used by IP CPU Used by mac layer in LAN models 96 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Analytical Simulation • Delay estimation • Capacity planning • Routing analysis • QuickPredict • Flow Analysis performs analytical simulations for steadystate analysis 97 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Comparison of Various Simulation Techniques 98 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Example of Discrete Traffic Simulation • TCP congestion window management • End-to-end delays at application layer Application E2E Delay Application Presentation Presentation Session Session Transport Congestion Window Transport Network Network Data Link Layer Data Link Layer Physical Physical 99 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Discrete Event Simulation • Packet retransmission due to varying acknowledgment delays • TCP/ATM connection setup delay for varying congestion levels of a network 100 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Comparison of Various Simulation Techniques 101 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Micro-Simulation – Delay Estimation • Delay estimator (t) for explicit packets due to additional aggregated traffic contending for a common resource (such as a link) • Retrospective micro-sim as lazy evaluation on real packet arrival • Sensitive to queuing schemes like PQ, CQ and WFQ Micro-simulation t r1 r2 b1 b2 b3 Time 102 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Analytical Coupled with MicroSimulation When real packets are separated by a long interval Lazy evaluation in two stages: analytical + micro-simulation Currently implemented for FIFO queues only Gain in simulation speed compared to pure micro-simulation Analytical-simulation Micro-simulation t + a r1 a r2 b1 b2 b3 Time 103 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Hybrid Simulation 104 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation 105 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab 1: Overview • Create a simple network with explicit traffic and run a simulation 2. Duplicate the network and replace the explicit traffic with corresponding background traffic • Run the simulation with background traffic • Assess/compare the accuracy and speed of the two traffic modeling approaches • Refer to lab manual for instructions 106 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab 1: Network Model Source nodes (video servers) with different ToS (1,2,3) Interface with WFQ Destination nodes 100 video users (MPEG4) - 3 available service classes Queuing delays ? 107 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Aggregated Traffic – Just a Number to Compute a Delay • Aggregated traffic in OPNET • Traffic flows (routed background traffic) • Device/link loads (static background traffic) • Common to both type of aggregated traffic • Internal representation: just a number for a given node/link • Effects: only one effect – to produce a delay • One difference between the two types of aggregated traffic • Traffic flows (routed background traffic) needs to be propagated to each node in the flow path tracer packets (propagators) 2Mbp s 2Mbp s 2Mbps 2Mbps 2Mbp s 2Mbps 2Mbp s 2Mbps 108 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Defining Traffic Flows • 3 basic steps 109 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Defining Traffic Flows (cont.) • Each flow is broken down into intervals as specified Interval : 300-600 seconds 110 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Simulating Traffic Flows • Refresher tracer packets I1 P1 P2 P3 P4 P5 I1 I2 I3 I4 I5 111 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Simulating Traffic Flows (cont.) • Sending new information on traffic level changes 0.0 start time = 150.0 I1 I2 I3 I4 I5 112 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Effects on Traffic Flows • Clipping • Effect: to reduce traffic flows to within bottleneck capacities • Modeled as: state information on each node, bps and pps rates inside tracer packet diminished downstream of the bottleneck • Segmentation: • Effect: to reduce packet size to within MTU • Modeled as: bps and pps rates inside the tracer adjusted to account for overhead due to segmentation • Load Balancing: • Split traffic flows proportionally among available paths • Modeled as: create copies of tracer packets with modified bps and pps rates 113 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Load Balancing Traffic Flows 0.375 0.75 0.5 * 0.75 = 0.375 0.375 0.375 0.25 0.25 0.25 114 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Outline • Motivation for traffic modeling • Traffic representation • Traffic generation: sources and import methods • Traffic modeling: comparison of various OPNET approaches • Lab #1 • Compare accuracy and speed of explicit traffic simulation with background traffic • Lab #2 • End-to-end delays using hybrid simulation 115 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab 2: Hybrid Simulation - Overview • Video Conferencing end-to-end delays • WAN – with background traffic • Create one explicit flow – hybrid simulation • Observe dependence of the explicit traffic end-to-end delay on Type of Service (ToS) used 116 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Lab 2: Network Model • WAN with many background traffic flows • One explicit video traffic flow from Seattle Houston (130 kbps – 360 kbps) • End-to-End delays ? • Refer to lab manual for instructions 117 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Modeling Large Networks 118 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Agenda • Conceptual goals • Software goals • Importing network topologies • Choosing aggregation levels • Import topology • Question and answer browser • • • • Using LAN models Importing traffic Using routed background traffic Managing projects and scenarios • • • • Import traffic Network browser Traffic browser Efficiency Modes • Navigating Large Topologies • Controlling Simulation Runtime • Effectively Using Background Traffic • • • • • Static Background Traffic Event Speed Parameter Specifying Traffic Growth Scheduling Automated Simulations Viewing and Editing Scheduled Simulations Log 119 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Overview – Large networks • The concept of a “large” network does not necessarily refer to the number of nodes or the geographic extent of a network. • A large network is any model that will generate a significant amount of events. This translates into longer simulations and memory limitation issues. • We will explore methods for increasing the efficiency of your models when the economies of scale become an issue. 120 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Common Pitfalls • OPNET is powerful software that tempts users with “grand designs”. • Common Pitfall: “I will model everything” • Developing models without clear direction and a solid understanding of the questions that need answering leads to inefficiency, and results that aren’t useful. 121 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Questions Should Drive Model Design • It essential to first determine which questions to answer. • Design the model to answer those questions. Don’t try to answer everything. • A key factor in effective modeling is flexibility. Realize that over the course of the modeling process that the questions may change. 122 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 LAN Models • Single nodes may be used to model entire LANs. 123 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Why Use LAN Models? • LAN models are a powerful mechanism for abstracting complex local area networks that may contain multiple nodes with the same configurations. • LAN models reduce clutter in the workspace. • LAN models use less memory. • LAN models generate fewer simulation events allowing simulations to run faster. These models represent the same network. 124 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Additional Information About LAN Models • LAN Models behave as if they were specific nodes modeled using OPNET. • The key difference is that you can collect statistics on the LAN models but not on the specific nodes and links within the model. 125 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Modeling Techniques • Design Accurate, Efficient Models • Two Techniques • Approximation • Reduction 126 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Approximation • Tradeoff: Precision vs. Performance • Loss in precision means higher variance • Overall results are still accurate • Approximation Approach • Apply a combination of analytically and explicitly modeled traffic • Allows you to limit the number of variables, while retaining the proper traffic behavior for the model 127 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Traffic Types • Three different types of traffic • Loads • Also called “Device/Link Loads” • Represent percentage of capacity being used • Can be imported or manually created • Flows • Visualized as demand objects • Can be imported or manually created • Packets • Provide detailed performance statistics • Delay, response time, jitter • Represent different types of application traffic • Can be imported from optional ACE module or manually created • All three can exist simultaneously in the network model 128 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing and Characterizing Applications • With the Application Characterization Environment (ACE) module, you can model any networked application by capturing the packets associated with that application, then importing them into Modeler. 129 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Link Loads • Represent utilization of individual links • Values are represented in percentage utilization for each time period • Utilization A->B • Utilization B->A • To set link loads manually: • Right-click a link, edit attributes • Expand “Background Utilization” attribute • Set utilization percentages for multiple time periods • To import data from management platforms: • Traffic / Import Device/Link Loads • MRTG • InfoVista • Concord eHealth-Network • Text Files 130 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Flows • Represent flow of network traffic between sources and destinations in network • Flows are represented in bits/sec and packets/sec • Flow data can be imported from management platforms • Cisco NetFlow (AS Aggregation or No Aggregation) • Cflowd • NetScout • NetScout Ngenius • NAI Distributed Sniffer / Sniffer Pro • Agilent NetMetrix • Spreadsheet / text files • You can add new flows manually by choosing: Protocols / IP / Demands / Configure Traffic Demands Among Selected Nodes 131 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Flows • Flows are a type of traffic demand. Demands appear as dotted blue lines from source to destination. • Right-click a traffic demand to edit its attributes or hide the demand • Use View / Demand Objects to hide/show all demands • Use Traffic / Open Flows Browser to quickly examine many flows 132 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Packets • Only used for discrete event simulation (DES) • Represent individual packets in network • Application traffic • LSAs • Application Configuration node used to globally define application traffic • LSAs automatically sent by routers during simulation • Capture the transient behavior of the network • • • • Convergence Latency Queue depth Protocol effects • Verify Service Level Agreement compliance 133 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Converting Loads to Flows • Import load traffic • Gather information about traffic characteristics in real network • Traffic / Convert Link Utilizations to Flows… • Give Modeler constraints: • List of possible endpoints of traffic flows • Max/min amounts of traffic per endpoint • Modeler performs conversion • Caveat: This is an approximation! • More constraints = more realistic flows • Flow traffic can be used for failure, routing, and QoS studies 134 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Summary: Traffic Modeling • Different traffic types available for different types of studies • Three types available for import or creation: • Flows • Loads • Packets • Flows are best choice for failure studies • Loads are often easiest to obtain and best for viewing utilization of current network • Packets are only used in discrete event simulation. Packets give the most detailed results and are the best choice for QoS studies. 135 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Object Reduction • Each and every object in a model uses memory. • Reducing the number of objects in a simulation allows for more efficient simulations, possibly allowing the workstation to overcome memory limitations (reduce swapping). • Modeler provides LANs, Clouds and devices with varying interfaces to allow you to keep the number of objects in the network model to a minimum without sacrificing precision. 136 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Object Reduction • LANs allow you to represent any number of workstations and a server as a single object. • IP Clouds abstract numerous IP devices into a single cloud object. • Each interface in a device requires memory. Creating devices that have the minimum amount of interfaces required for a model reduces memory needed to run simulation. • Example-- If all the hubs in a model will only have 8 connections, it is more efficient to use an ethernet8_hub than an ethernet64_hub. Even if this doesn’t represent your actual hardware, it will not affect the precision of the simulation. 137 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Alternative Solutions • There are other solutions that don’t involve model design. • These alternative solutions can be characterized as “brute force” methods. • The advantage to alternative solutions is that it gives you more latitude in your model designs. • Increasing physical memory is always an effective way to increase workstation performance. • Increasing the swap space is another effective method to get a better performance from a computer. 138 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Controlling Simulation Runtime • Every protocol in Modeler has attributes associated with them. These attributes represent real-world application of a protocols procedures and techniques. • In many cases, although representing a protocol’s actual behavior, certain attributes may not add value to a user’s model. In fact they will generate events that are not helpful to the results of the model and will actually increase simulation run-time. • Modeler accounts for this by enabling certain efficiency modes in order to decrease the number of unimportant events and accelerate simulation runtime. 139 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Controlling Simulation Runtime • When configuring a simulation, you will be able to view and edit a list of simulation attributes. These attributes will change based on the protocols being modeled. • Among these attributes are a variety of efficiency modes that are enabled. • Right-clicking on a simulation attribute will provide you with a complete description of that attribute. 140 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Importing Topology Information • OPNET can import topologies from • ACE • ATM Text files • HP Network Node Manager • Device Configurations (MVI Module) • XML files • VNE Server 141 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Aliases • An alias is a name used to reference a particular node in OPNET. • An alias may be an IP address, MAC address or a user friendly name. • An object may have multiple aliases. • These aliases are used as endpoints for imported traffic. • LAN models retain the aliases for all nodes that are contained in the LAN. • This makes it possible to address traffic to the appropriate LAN model. 142 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Navigating Large Topologies • OPNET provides you with various tools to facilitate the locating and selecting of nodes in a large network: • Select Objects Logically • Network Browser 143 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Edit / Select Objects • Choose Edit / Select Objects to select certain objects throughout network based on the value of attributes. • Ex: Select all links with a data rate greater than 1.544 Mbps 144 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Network Browser • The Network Browser can be used to locate objects in your network. • Choose View / Show Network Browser • Type a search string into the “Find” box to show objects with that string in their names. 145 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Network Browser • To view an object’s attributes, right-click the object in the workspace or the list and select “Edit Attributes.” 146 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Managing Projects and Scenarios • Managing scenarios allows you to examine the status of scenario results, change project/scenario names and run multiple simulations sequentially. Change the project name here. Change the scenario name here. Collect results on multiple scenarios by changing the results column to <recollect>. Clicking OK will start a simulation run for each scenario with <recollect> set. Change the simulation duration. Ok will write all of the changes to the project. 147 © copyright 2003 OPNET Technologies, Inc. Modeler Day 3 Summary • Networks can be imported in a variety of manners. • Modeler’s power as modeling software becomes evident with the analysis of large networks. As the size of the model increases so does the importance of efficient modeling. • Avoiding common pitfalls and understanding the efficiency techniques inherent in Modeler leads to useful results and efficient models. • By skillfully using the combination of the three types of traffic, you can achieve a comfortable balance of performance and precision. 148 © copyright 2003 OPNET Technologies, Inc.