simulation and emulation with nctuns professor nelson fonseca [email protected]

Simulation and Emulationwith NCTUns

Professor Nelson [email protected]

NCTUns - Professor Nelson Fonseca 2

Outline

Introduction Simulation X Emulation Details

Features Installation Utilization Examples

Conclusions References


Introduction


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


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


SimulationX

Emulation


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)


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


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


Details


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.


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)


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, ...


Features (4)

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


Features (5)

Kernel re-entering methodology


Installation (1) Download from: http://nsl10.csie.nctu.edu.tw/products/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

http://nsl10.csie.nctu.edu.tw/products/nctuns/download/download.php




















Installation (2)

Hardware requirements: RAM memory 256 MB Pentium 1.6GHz processor At least 200MB free disk space

Multi-core processors are supported


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


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


Utilization (2)

Each simulation server = kernel modifications + nctunsse + protocol modules + coordinator


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


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


Utilization (5)

How to use the GUI?


Utilization (6) Draw topology


Utilization (7)


Utilization (8) Edit property


Utilization (9)


Utilization (10) Run simulation


Utilization (11)


Utilization (12)


Utilization (13) Playback


Utilization (14)


Utilization (15)


Utilization (16)


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 (tun[0-9]*

devices) .tcl: scenario details

One example of each file is available at http://www.lrc.ic.unicamp.br/~daniel/trento/nctuns/

http://www.lrc.ic.unicamp.br/~daniel/trento/nctuns/















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 <file.tcl>

<file.tcl> is generated by the GUI Wait for the results


Examples (1)

Scenario 1 Network topology: 2 hosts connected by an

ethernet link Protocols: TCP and UDP Applications: rtcp/stcp Devices:


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


Examples (3)


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


Conclusions


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


References

http://nsl10.csie.nctu.edu.tw/Official website

http://nsl.csie.nctu.edu.tw/nctuns.htmlList of related papers

http://nsl10.csie.nctu.edu.tw/support/documentation/GUIManual.pdfGUI user manual

http://nsl10.csie.nctu.edu.tw/support/documentation/DeveloperManual.pdfDeveloper manual

http://nsl10.csie.nctu.edu.tw/support/documentation/DemoVideos/Videos of NCTUns in action

http://nsl10.csie.nctu.edu.tw/









http://nsl.csie.nctu.edu.tw/nctuns.html













http://nsl10.csie.nctu.edu.tw/support/documentation/GUIManual.pdf












http://nsl10.csie.nctu.edu.tw/support/documentation/DeveloperManual.pdf












http://nsl10.csie.nctu.edu.tw/support/documentation/DemoVideos/











simulation and emulation with nctuns professor nelson fonseca [email protected]

Documents

real links slide

different real applications

new real applications

wireshark slide

specific applications

real devicesprotocols

network devices

simulation servers