Communication Networks Research CNR Lab.

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Network Simulators

• 2009. 3. 16
• Dan Keun Sung
• dksung_at_ee.kaist.ac.kr

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Part 1. OPNET
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1. OPNET? (1)

• OPNET IT Guru - diagnose application performance
  problems, validate changes to server and router
  configurations, and plan for growth and high
  availability.
• OPNET SP Guru - compete more effectively with
  advanced configuration troubleshooting, change
  validation, predictive planning, and automated
  network design.
• OPNET WDM Guru - design resilient, cost-effective
  optical networks with its unique multi-layered
  network presentation, broad technology support,
  and cutting edge optimization and design
  capabilities.

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1. OPNET? (2)

• OPNET Modeler - accelerates RD for engineers
  designing network equipment, communication
  protocols, and systems.
• OPNET Netbiz - is a customizable platform for
  automating network design, provisioning,
  proposals, and analysis that incorporates
  proprietary algorithms and design rules.

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2. Standard models (1)

• Data Link Layer Technology

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2. Standard models (2)
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2. Standard models (3)

• Network Layer Protocols

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2. Standard models (4)

• Routing Protocols

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2. Standard models (5)

• Transport Layer Protocols
• Physical Layer Technologies

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2. Standard models (6)

• Utilities
• Hybrid Simulation Objects

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2. Standard models (7)

• Application Layer Models

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2. Standard models (8)

• Radio/Wireless Models
• Vendor Device Models

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3. Specialized models

• Multi-Protocol Label Switching MPLS
• Universal Mobile Telecom System UMTS
• Data Over Cable System Interface Specification
  DOCSIS
• Private Network-Network Interface PNNI
• IP Multicasting Ipmc
• Circuit-Switched CK_SW
• Advanced Servers SSM
• IP Version 6 IPv6

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4. Modeler Characteristics (1)

• Boosting Network RD Productivity
• Improving Product Quality
• Reducing Time-to-Market
• Hierarchical network models
• Object-oriented modeling
• Clear and simple modeling paradigm
• Wireless, point-to-point, and multipoint links
• Finite state machine modeling
• Geographical and mobility modeling
• Comprehensive support
• Total openness

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4. Modeler Characteristics (2)

• Integrated analysis tools
• Animation
• Financial cost attribute for devices
• Integrated debugger
• Import data from text files, XML, and popular
  tools
• Comprehensive library of detailed protocol and
  application models
• Network devices
• Convenient licensing
• Highly efficient simulation engine
• Runtime environment
• Windows 2000/XP, and UNIX

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5. Decision Making Process of Modeler (1)

• Model Building and Configuration
• Network Editor - define or change network
  topology models
• Node Editor - define or change data flow (systems
  architecture) models
• Process Editor - define or change control flow
  (behavioral logic) models

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5. Decision Making Process of Modeler (2)

• Running Simulations
• Simulation Engine - define and run simulation
  studies using models constructed with the OPNET
  Editors
• Interactive Debugging Engine - interact with
  running simulations
• Analyzing Results
• Analysis Engine- display and compare statistical
  results
• Animation Viewer - watch dynamic behavior of
  models during simulation runs

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Part 2. NS-2
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ns-2, the network simulator

• Discrete event simulator
• simple model
• Focused on modeling network protocols
• wired, wireless, satellite
• TCP, UDP, multicast, unicast
• web, telnet, ftp
• ad hoc routing, sensor networks
• infrastructure stats, tracing, error models, etc

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ns goals

• Support networking research and education
• protocol design, traffic studies, etc.
• protocol comparison
• Provide a collaborative environment
• freely distributed, open source
• share code, protocols, models, etc.
• allow easy comparison of similar protocols
• increase confidence in results
• more people look at models in more
  situations
• experts develop models
• Multiple levels of detail in one simulator

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Alternatives

• operational details, but
• limited scale
• expensive, limited flexibility
• better, but higher overhead
• can provide understanding
• but limited details
• Important niches
• limited re-use
• fill niches

• Experimentation
• private laboratories
• public test beds (ex. CAIRN)
• shared labs (ex. Utah Emulab)
• Analysis
• Other simulators
• custom simulators
• other general sims

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ns history

• Began as REAL in 1989
• ns by Floyd and McCanne at LBL
• ns-2 by McCanne and the VINT project
• (LBL, PARC, UCB, USC/ISI)
• Currently maintained at USC/ISI, with input from
  Floyd et al.

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ns components

• ns, the simulator itself
• nam, the Network AniMator
• visualize ns (or other) output
• GUI input simple ns scenarios
• pre-processing
• traffic and topology generators
• post-processing
• simple trace analysis, often in Awk, Perl, or Tel

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ns models

• Traffic models and applications
• web, FTP, telnet, constant-bit, Real Audio
• Transport protocols
• unicast TCP (Reno, Vegas, etc.), UDP
• multicast SRM
• Pouting and queueing
• wired routing, ad hoc routing and directed
  diffusion
• queueing protocols drop-tail, RED, fair
  queueing, etc.
• Physical media
• wired (point-to-point, LANs), wireless (multiple
  propagation models), satellite