Apresenta

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Simulation and Emulation with NCTUns
Professor Nelson Fonseca nfonseca_at_ic.unicamp.br
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Outline

• Introduction
• Simulation X Emulation
• Details
• Features
• Installation
• Utilization
• Examples
• Conclusions
• References

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Introduction
4
Main features

• Simulates and emulates network protocols
• Open source
• Modified Linux kernel
• GUI and shell commands
• Client-server model to allow communication
  between simulation/emulation engine and interface
• Since 2002 (version 1.0)?
• Version 5.0 released in 2008

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Comparing with traditional simulators

• Uses native Linux TCP/IP stack
• Interacts with real devices in virtual networks
• Allows experiments with real applications
• There is no need to change the real applications
• Allows remote simulations and concurrent
  simulations
• Easy to create simulation servers
• Can take advantage of multiple cores/processors

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Simulation X Emulation
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Simulation

• Ideal to create several different scenarios
• Ideal when there isn't available testbeds
• Results not always the same as the reality
  because the applications are not the same
• Example applications in the ns-2 simulator need
  to be rewritten to run inside the simulator
  (problem recently solved with ns-3)?

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Emulation

• Uses real applications and network devices
• More realistic scenarios and more trustable
  results
• Can combine virtual and real devices/protocols
• Example how will be the behaviour of a real
  application over a new transport protocol?
• Less flexible than simulations
• the characteristics of the emulated links are
  limited to the characteristics of the real links

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NCTUns

• Simulator and emulator
• It is possible to use as a conventional simulator
• It is possible to evaluate new real applications
  over different network configurations
• It is possible to evaluate new protocols with
  different real applications
• It is possible to capture the generated traffic
  and use it as input to packet analysers like
  wireshark

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Details
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Features (1)?

• Support to several protocols is already included
• IEEE 802.3, IEEE 802.11, IEEE 802.16, Learning
  bridge protocol, Spanning tree protocol, ...
• IP, Mobile IP, RIP, OSPF, OBS, GPRS, ...
• TCP, UDP, SDP, ...
• HTTP, FTP, telnet, ... ( any real application)?
• Some specific applications included
• stcp/rtcp - Greedy TCP traffic
• ttcp - Greedy TCP/UDP trafic
• stg/rtg - Greedy TCP/UDP traffic, trace driven,
  self-similar traffic, on-off, constant-bit-rate,
  and various packet streams.

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Features (2)?

• Support to several links and devices is already
  included
• PPP link, ethernet link, ...
• Host, hub, switch, router, ...
• QoS Diffserv boundary/interior routers
• Optical burst/circuit switch
• External host, external router (emulation)?

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Features (3)?

• Creates virtual interfaces to simulate the
  devices of the scenario
• Inspiration from loopback interface
• Utilizes IP address 1.0.0.0
• During the simulation it is possible to see the
  interfaces with the commands /sbin/ifconfig or
  /sbin/route
• Interfaces named tun0, tun1, tun2, ...

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Features (4)?

• How loopback works? (Host 1 and Host 2 are the
  same host)?

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Features (5)?

• Kernel re-entering methodology

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Installation (1)?

• Download from http//nsl10.csie.nctu.edu.tw/produ
  cts/nctuns/download/download.php
• Software requirements
• Operating system Fedora Linux 10.0
• gcc and g compiler
• X window system
• Tcl
• rsh server and rlogin
• SELINUX disabled
• Firewall disabled
• root privileges

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Installation (2)?

• Hardware requirements
• RAM memory 256 MB
• Pentium 1.6GHz processor
• At least 200MB free disk space
• Multi-core processors are supported

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Installation (3)?

• Installation procedure
• Uncompress the downloaded .tar.gz file
• Run ./install.sh
• Reboot
• Select one of the two new kernels
• NCTUns
• NCTUns (ELP) If you want to use more than one
  core/processor

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Utilization (1)?

• Basic components (binaries)?
• nctunsclient GUI interface between user and
  system
• nctuns shell interface between user and system
• nctunsse NCTUns core
• dispatcher Manage the simulation requests. Can
  control multiple coordinators running in
  different machines
• coordinator Receives the simulation from the
  dispatcher and forward it to the nctunsse

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Utilization (2)?

• Each simulation server kernel modifications
  nctunsse protocol modules coordinator

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Utilization (3)?

• Folders organization
• tools executable programs of various
  applications and tools pre-installed by NCTUns
  5.0
• bin executable programs of the GUI program,
  dispatcher, coordinator, and the simulation
  engine
• etc configuration files needed by the
  dispatcher and coordinator programs
• BMP icon bmp files uses by the GUI program
• lib libraries used by the simulation engine

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Utilization (4)?

• Execution order
• dispatcher
• Waits client connection via TCP port 9800
• Waits coordinator connection via TCP port 9810
• coordinator
• Connects to dispatcher
• nctunsclient or nctuns
• Connects to dispatcher to send the scenario and
  waits the end of the simulation. The nctunsse is
  started by the coordinator

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Utilization (5)?

• How to use the GUI?

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Utilization (6)?

• Draw topology

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Utilization (7)?
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Utilization (8)?

• Edit property

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Utilization (9)?
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Utilization (10)?

• Run simulation

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Utilization (11)?
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Utilization (12)?
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Utilization (13)?

• Playback

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Utilization (14)?
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Utilization (15)?
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Utilization (16)?
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Utilization (17)?

• Main simulation files
• .emu external routing table (needed to
  emulation)?
• .ndt nodes identification
• .tfc list of commands to be executed
• .srt-l internal routing table (tun0-9
  devices)?
• .tcl scenario details
• One example of each file is available at
  http//www.lrc.ic.unicamp.br/daniel/trento/nctuns
  /

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Utilization (18)?

• To run without the GUI
• Create the basic scenario from the GUI (It is
  easier)?
• Make the necessary changes in the files
• Run nctuns ltfile.tclgt
• ltfile.tclgt is generated by the GUI
• Wait for the results

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Examples (1)?

• Scenario 1
• Network topology 2 hosts connected by an
  ethernet link
• Protocols TCP and UDP
• Applications rtcp/stcp
• Devices

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Examples (2)?

• Scenario 1 Applications configuration
• To simulate data transfer between host 1
  (1.0.1.1) and hosts 2 (1.0.1.2) via TCP using
  stcp and rtcp
• Host 1 stcp -p 8000 1.0.1.2
• Sending TCP segments to 1.0.1.2 at port 8000
• Host 2 rtcp -p 8000
• Receiving TCP segments from port 8000

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Examples (3)?
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Examples (4)?

• Scenario 2
• To simulate data transfer between host 1
  (1.0.1.1) and host 2 (1.0.1.2) via UDP using stg
  and rtg
• Host 1 stg -u 1000 50 -m 50 50 -p 8000 1.0.1.2
• Sending UDP datagrams to 1.0.1.2 at port 8000.
  Transmission rate limited to 50Mbps and packet
  size equal to 1000 bytes.
• Host 2 rtg -u -p 8000
• Receiving UDP datagrams from port 8000

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Conclusions
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Conclusions

• Joins simulation and emulation in one tool
• Intuitive and simple GUI
• Good if there is a few number of scenarios
• Hard to manage if there is a large number of
  scenarios
• Good documentation
• Several demo videos at official website

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References

• http//nsl10.csie.nctu.edu.tw/
• Official website
• http//nsl.csie.nctu.edu.tw/nctuns.html
• List of related papers
• http//nsl10.csie.nctu.edu.tw/support/documentatio
  n/GUIManual.pdf
• GUI user manual
• http//nsl10.csie.nctu.edu.tw/support/documentatio
  n/DeveloperManual.pdf
• Developer manual
• http//nsl10.csie.nctu.edu.tw/support/documentatio
  n/DemoVideos/
• Videos of NCTUns in action