The NCTUNS 1.0 Network Simulator

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NCTUns 5.0 Network Simulator and Emulator

• Prof. Shie-Yuan Wang
• shieyuan_at_cs.nctu.edu.tw
• Department of Computer Science
• National Chiao Tung University, Taiwan

Network and System Laboratory
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Outline

• Introduction

• Architecture

• NCTUns features

• Simulation methodology

• Product status

• Concluding remarks

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Introduction
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Introduction

• The NCTUns network simulator and emulator is
  developed at NCTU, Taiwan. Its predecessor is the
  Harvard network simulator (invented by Prof. S.Y.
  Wang in 1999).

• By using a novel simulation methodology, it can
  do several tasks that traditional network
  simulators cannot easily do.

• After more than eight years development, it has
  become a useful tool.

• Many people are using it. (Use the Google to
  search it for yourself.)

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Now, its Impact Is Ranked 2 by Google Taiwan
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The IEEE Network Magazine reports this tool in
its July 2003 issue.
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Selected as a Research Demo by ACM MobiCom02
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Again selected by MobiCom 2003
Ranked 1 of the 12 selected
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First local workshop on 12/05/2002
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Second local workshop on 12/12/2003
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A Tutorial Made at IEEE Vehicular Technology
Society, Taipei Chapter 09/22/2004
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Selected as a tutorial by IEEE MASCOT 2004
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Selected as a Demo by IEEE INFOCOM 2005
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Selected as a tutorial by SPECTS 2005, Society
for Simulation, International.
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Selected as an exhibition by IEEE ICC 2007, 24-28
June 2007, Glasgow, UK
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Invited as a DEMO by IEEE WiVEC08, September
2008, Calgary, CA
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Main Unique Features

• The real-world TCP/IP protocol stack is directly
  used to generate accurate simulation results.

• Real-world application programs can directly be
  run on a simulated network

• Realistic network traffic can be generated.

• Their performances can be evaluated under
  different network conditions.

• The applications developed at the simulation
  stage can be immediately deployed in the real
  world without any change.

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Main Features (2)

• Using an open-system (source) architecture to
  allow a researcher to easily add his (her) own
  protocol modules into the simulator

• Simulation methodology has been endorsed by
  several journal papers (Computer Networks 2002,
  Computer Networks 2003, Wileys Wireless
  Communication and Mobile Computing 2005,
  Elseviers Simulation Modeling Theory and
  Practice 2007), two book chapters published by
  Nova Science Publisher 2006 and 2008, and two
  conference papers (IEEE INFOCOM99, WiVEC08).

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Network Simulation Capabilities

• NCTUns 2.0 can simulate Ethernet-based fixed IP
  networks, 802.11 (b) wireless LANs, mobile ad hoc
  networks, GPRS cellular networks, optical
  networks (circuit-switching and optical
  burst-switching), Diffserv QoS networks etc.

• NCTUns can function as an emulator, too! (See
  Chapter 7 of this book ISBN 1-59454-830-7)

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Architectures
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Eight Components
GUI Client
Job Dispatcher
Coordinator
Daemons
Applications
Protocol Modules Simulation Engine
Kernel Patches (Fedora 9.0 Linux 2.6.25)
Simulation Server
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Distributed Architecture
Simulation Server
Paris
GUI Client
Dispatcher
Tokyo
Boston
NCTU, Taiwan
Simulation Service Center
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Open-System Architecture
Protocol modules
Module API
Simulation Engine
User-level Simulator
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Main GUI Components

• Topology editor
• Draw a network topology

• Node editor
• Specify a nodes protocol stack

• Performance monitor
• Monitor and plot performance curves

• Packet animation player
• Playback packet transfer animation

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Topology Editor
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Node Editor
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Performance Monitor
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Packet Animation Player
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NCTUns 3.0 New Features
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IEEE 802.11(b) Dual-Radio Wireless Mesh Networks

• Each access point has two interfaces
• One operates in the infrastructure mode serving
  standard IEEE 802.11(b) client stations
• The other operates in ad hoc mode used to
  wirelessly forward packets among access points.
• Low deployment cost, high reliability
• Example
• The wireless mesh network deployed in Taipei is
  an IEEE 802.11(b) wireless mesh network with
  8,000 mesh access points.

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Client
Mesh Access Point
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IEEE 802.11(e) QoS Wireless LAN

• Provide QoS guarantee for IEEE 802.11(e) client
  stations.
• The IEEE 802.11(e) access point polls each
  associated IEEE 802.11(e) client station to give
  them enough transmit opportunities to meet their
  bandwidth requirement.

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IEEE 802.11(e) Access Point
IEEE 802.11(e) Client
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Tactical and Active Mobile Ad Hoc Networks

• Can be used to study future combat system (FCS)
  or any active mobile ad hoc network where mobile
  nodes can actively and dynamically change their
  moving behaviors according to the current
  environment conditions or after receiving a
  command from other mobile nodes.
• Thales Group Inc. (a security and defense
  company, with 60,000 employees worldwide) has
  purchased two NCTUns commercial licenses for
  their military projects.

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Target node
Chasing node
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Directional Antennas

• Researches about networks using directional
  antennas have become increasingly popular.
• Support 3dB beamwidth 60-degree and 120-degree
  directional and steerable antennas.
• Use more realistic antenna gain patterns
  pre-computed and stored in tables to compute the
  received power of a packet.
• Antennas can rotate or be set to point to a
  particular direction.
• Can increase transmission range, reduce signal
  interference, and provide security.

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Antenna Gain Patterns
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NCTUns 4.0 New Features
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IEEE 802.16(d) WiMAX Networks

• Both the PMP and mesh modes are supported.
• Complete implementation of the standard
  specifications
• Simulation results have been validated against
  mathematical theoretic results.
• Two conference papers have been published using
  this tool.
• Many people in the world have sent emails to us
  asking to use this tool for their WiMAX
  researches.

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WiMAX PMP mode
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WiMAX mesh mode
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DVB-RCS Satellite Networks

• Support DVB-RCS GEO satellite networks
• Complete implementation of the standard
  specifications
• Simulation results have been validated against
  mathematical theoretic results.
• European Space Agency would like to use this tool
  for its research projects.

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DVB-RCS Basic Network
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DVB-RCS Extended Network
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ITS Wireless Vehicular Networks

• Researches on wireless vehicular networks have
  become increasingly popular (e.g., VANET, WiVEC,
  V2VCOM conferences, etc.)
• NCTUns is the first (only) simulator in the world
  that tightly integrates network and traffic
  simulation.
• NCTUns supports V2V and V2I capabilities.
• NCTUns will be used by Telcordia Technologies
  Inc. for a EU IVC (inter-vehicle communication)
  project EU F-7 Call-2
• NEC Europe Inc. wants to use NCTUns for their EU
  projects and introduce NCTUns into the EU ITS
  standardization meetings.

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Construct a road network
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Select car profile Deploy car on the road
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Multi-interface Mobile Node

• Nowadays a mobile device is equipped with
  multiple heterogeneous wireless interfaces.
• This allows it to use the most cost-effective
  network to connect to the Internet.
• Many related research topics have emerged
  Handover, multi-homing, trunking, etc.
• Other than NCTUns, very few (if there is any)
  network simulators provide this capability.
• In NCTUns, a multi-interface node is equipped
  with (1) 802.11(b) ad hoc mode , (2) 802.11(b)
  infrastructure mode, (3) GPRS, and (4) DVB-RCST
  satellite interfaces.

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Multi-interface Car
Multi-interface Mobile Node
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Create multiple sockets each bound to an
interfaces IP address
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NCTUns 5.0 New Features
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IEEE 802.11(p)/1609 Wireless Vehicular Networks

• Wireless vehicular network research is becoming
  more and more popular.
• IEEE VTS defines IEEE 802.11(p)/1609 standards
  for this type of networks.
• NCTUns is the first network simulator that
  provides supports for IEEE 802.11(p)/1609 network
  simulations.
• For this reason, IEEE WiVEC 2008 conference
  (supported by IEEE VTS) invited Prof. Wang to
  demo NCTUns in its demo session.

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OBU
OBU
RSU
OBU
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IEEE 802.16(e) Mobile WiMAX Networks

• Recently, IEEE 802.16(e) Mobile WiMAX has become
  more popular than IEEE 802.16(d) fixed WiMAX.
• Complete implementation of the standard
  specifications
• Simulation results have been validated against
  mathematical theoretic results.
• Can work with Mobile IP protocol to roam across
  different IP subnets.

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30 Realistic Wireless Channel Propagation and
Fading Models

• Realistic wireless channel propagation and fading
  models are very important in generating
  high-fidelity simulation results.
• Over 30 channel models for various wireless and
  mobile environments are provided.
• They can be easily chosen/replaced in the GUI.

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Parallel Simulations on Multi-core Machines

• Recently, multi-core machines have been popular
  on the market.
• Performing parallel simulations on these cores to
  speed up simulations is highly desired.
• Currently, NCTUns supports parallel simulations
  for fixed networks.
• Parallel simulations for wireless networks will
  be supported in the next version.

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Simulation Methodology
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Novel Simulation Methodology

• Use a kernel re-entering technique (invented by
  Prof. Wang in 1999) to provide two advantages

• Use real-life protocol stacks to simulate
  networks
• ? simulation results are more accurate.

• All existing real-life application programs can
  directly run on a simulated network
• ? can test the performance of any real-life
  application program and generate realistic
  network traffic.

• These advantages cannot be easily achieved by
  traditional network simulators such as OPNET
  modeler and ns-2.

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Idea Was Inspired from the lo0 Loopback Interface
Suppose that we want to simulate the following
basic network
stcp
rtcp
1.0.1.2
Host 1
Host 2
Subnet 1.0.1
1.0.1.1
1.0.1.2
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Actually stcp and rtcp Can Be Run on the Same
Machine
stcp
rtcp
127.0.0.1
User level
Kernel level
Host
lo0
127.0.0.1 (The IP address assigned to the
loopback interface)
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Actually These Two Slides Differ Very Slightly

• The used network applications are the same.

• The used TCP/IP protocol stacks are the same.

• The only difference is in the used links
• The real-life physical link vs. the loopback
  memory link

• If we can intercept packets so that they are not
  looped back automatically, we can direct them to
  our simulation engine. This way, the simulation
  engine can simulate their transmission time and
  their signal propagation delay over the link.

• This is the idea of this simulation methodology!

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Simulation engine
1999 version
This is why we claim (1) all real-world
application programs can be run and (2) the
real-world TCP/IP protocol stack is directly used.
We use tunnel interfaces to replace lo0
interface. This way, we can intercept packets and
direct them into the simulation engine.
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Current version
Various protocol modules now can be flexibly
added to the simulation engine.
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A Configuration Example
rtcp
stcp 1.0.3.2
1.0.3.1
tun1
2
1
tun2
1.0.3.2
Assuming 1.0.3.X is the subnet.
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A Route Conflict Problem

• The simulation methodology presented so far works
  very well for a single-hop network.

• However, we will encounter a route conflict
  problem when the network is extended to
  multi-hops.

• This is because we use only one machine to
  simulate all routers and store their routing
  entries together.

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Problem Example
route add 1.0.3.2 interface tun1 route add
1.0.4.1 interface tun1 route add 1.0.4.2
interface tun1
route add 1.0.3.1 interface tun2 route add
1.0.4.2 interface tun3
Conflict!
route add 1.0.4.2 interface tun1 route add
1.0.4.2 interface tun3
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S.S.D.D IP Address Scheme

• We solve this problem by internally using the
  S.S.D.D IP address scheme for an application to
  send its packets to its destination node.

• The meaning of S.S.D.D. is SrcSubnetID .
  hostonSrcSubnet . DstSubnetID .
  hostonDstSubnet.

• However, a NCTUns user need not know and use this
  strange scheme. He (she) can still use the normal
  1 . 0 . subnetID . host address scheme. The
  kernel hides all the details.

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The S.S.D.D Scheme to Solve the Route Conflict
Problem
rtcp
stcp 3.1.3.2
route add 3.1.3.2 interface tun1 route add
3.1.4.1 interface tun1 route add 3.1.4.2
interface tun1
route add 3.2.3.1 interface tun2 route add
3.2.4.2 interface tun3 route add 4.1.3.1
interface tun2 route add 4.1.4.2 interface tun3
No conflict Now!
route add 3.1.4.2 interface tun1 route add
3.2.4.2 interface tun3 route add 4.1.4.2
interface tun3
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Product Status
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Product Was First Released on November 1, 2002
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Download Web Site Is Here
As of Oct. 22 2008, more than 12,747 people from
128 countries have registered and downloaded
this tool since its release on November 1, 2002.
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NCTUns users are all over the world.
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Many emails have arrived praising NCTUns or
asking how to purchase NCTUns.
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Dear Prof. Wang, We have been very impressed by
NCTUns and many of its amazing capabilities!  The
simulation-emulation integration capabilities are
quite remarkable.  We have been quite impressed
with the design of the GUI interface.  We are
going to be demo-ing NCTUns to another network
analysis software development group within our
company to show them some of the exciting
features of NCTUns. Zeke Weeks Consulting
Services Specialist ATT Government Solutions,
Inc. Suite 5077 1900 Gallows Road Vienna, VA
22182 Email zweeks_at_att.com
NCTUnss emulation and GUI capabilities are
highly appreciated by ATT experts.
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NCTUns Is Compared with Other World-Famous
Network Simulators
Dartmouth
Cornell
UIUC
Data source IEEE Communication Magazine, July
2006 Issue
NCTU
USC
Budapest
UC Berkeley
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Concluding Remarks
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Concluding Remarks

• NCTUns 5.0 now is a high-quality professional
  network simulator and emulator with many unique
  advantages over traditional ones.

• Based on users feedback, we are still continuing
  to improve NCTUns.

• What new features should be included in NCTUns
  6.0?

• You are very welcome to tell me

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Thank you. Q A