Transcript nctuns-final

Simulation and Emulation
with NCTUns
Professor Nelson
Fonseca
[email protected]
Outline
Introduction
 Simulation X Emulation
 Details
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Features
 Installation
 Utilization
 Examples
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Conclusions
References
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Introduction
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Main features
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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
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Uses native Linux TCP/IP stack
Interacts with real devices in virtual networks
Allows experiments with real applications
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There is no need to change the real applications
Allows remote simulations and concurrent
simulations
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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
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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
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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
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Simulator and emulator
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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)
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Support to several protocols is already included:
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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:
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stcp/rtcp - Greedy TCP traffic
ttcp - Greedy TCP/UDP trafic
stg/rtg - Greedy TCP/UDP traffic, trace driven, selfsimilar traffic, on-off, constant-bit-rate, and various
packet streams.
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Features (2)
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Support to several links and devices is already
included
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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)
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Creates virtual interfaces to simulate the devices of
the scenario
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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)
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How loopback works? (Host 1 and Host 2 are the
same host)
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Features (5)
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Kernel re-entering methodology
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Installation (1)
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Download from:
http://nsl10.csie.nctu.edu.tw/products/nctuns/download/download.php
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Software requirements:
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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)
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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)
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Installation procedure
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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)
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Basic components (binaries)
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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)
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Each simulation server = kernel modifications +
nctunsse + protocol modules + coordinator
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Utilization (3)
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Folders organization
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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)
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Execution order
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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)
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How to use the GUI?
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Utilization (6)
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Draw topology
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Utilization (7)
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Utilization (8)
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Edit property
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Utilization (9)
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Utilization (10)
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Run simulation
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Utilization (11)
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Utilization (12)
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Utilization (13)
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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)
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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 (tun[0-9]* 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)
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To run without the GUI
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Create the basic scenario from the GUI (It is
easier)
Make the necessary changes in the files
Run nctuns <file.tcl>
 <file.tcl> is generated by the GUI
Wait for the results
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Examples (1)
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Scenario 1
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Network topology: 2 hosts connected by an
ethernet link
Protocols: TCP and UDP
Applications: rtcp/stcp
Devices:
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Examples (2)
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Scenario 1 – Applications configuration
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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)
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Scenario 2
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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
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Good if there is a few number of scenarios
Hard to manage if there is a large number of
scenarios
Good documentation
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Several demo videos at official website
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References
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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/documentation/GUIManual.pdf
GUI user manual
http://nsl10.csie.nctu.edu.tw/support/documentation/DeveloperManual.pdf
Developer manual
http://nsl10.csie.nctu.edu.tw/support/documentation/DemoVideos/
Videos of NCTUns in action
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