GenSyn framework for synthetic and realistic traffic generation

1
GenSyn - framework for synthetic and realistic
traffic generation

• Poul Heegaard,
• NTNU Department of Telematics
• Telenor RD

2
The need for a traffic generator

• Controllable
• Scalable
• Re-producible
• Realistic traffic

New services
New network mechanisms
3
Framework for source modelling

• Different activity levels
• Stochastic model
• Communication model
• Source composition

4
GenSyn - Overall framework
Composite sourcewith comm. states
generate
finish
generate
HTTPconnect URLconnect Socket
Video
finish
URLconnect Socket
TCP
UDP
IP
Off the shelf workstation
???
5
Web source (Example 1)
Ftp avg. size 220 kbytes Web from url list
Init 160 sources
Init 140 sources
Stocastic State Space
Comm. state space
(1-p)a
l
Idle
Read
Download
pa
6
VoIP (Example 2)
Init 1000 sources
Stocastic State Space
Comm. state space
Talk

l 1/20
-
1


min
352 ms



Idle
Connect

a 1/3
-
1


Silent

min
650 ms

7
MPEG video (Example 3)

Init 100 sources
Stocastic State Space
Comm. state space
l 1/20
-
1


min
Idle
Send
UDP packets in frame i
1024 bytes

1024 bytes

1024 bytes

1024 bytes

1024 bytes

time

i

40 ms

40 ms

i1

8
Constant Bitrate (Example 4)

Init 50 sources
Stocastic State Space
Comm. state space
l 1
-
1


sec


Send
Idle

a 1/3
-
1


a 1/3
-
1


min
min
Send
9
GenSyn summary

• Java-based, portable traffic generator
• Flexible and scalable
• Stochastic state models of user behaviour
• Link to protocol stack for real packet generation

10
GenSyn propertiesscalability (ftp ex)
Theoretical throughput
Observed throughput
11
GenSyn propertiesself-similarity
Less than 100 active users
TCP (85 byte)
UDP (15 byte)
Poisson
12
Comment onSelf-similarity vs. Poisson

• Goodbye Poisson
• W. E. Leland, M. S. Taqqu, W. Willinger, and D.
  V. Wilson. On the Self-Similar Nature of Ethernet
  Traffic. In IEEE/ACM Transactions on Networking,
  1994.
• Welcome back Poisson
• Thomas Karagiannis, Mart Molle, Michalis
  Faloutsos Andre Broido A Nonstationary Poisson
  View of Internet Traffic. IEEE INFOCOM 2004

• Palm-Khintchine Theorem
• The superposition of a large number of
  independent
• renewal processes is approximately a Poisson
  process.
• infinite number of sources
• sources are independent of eachother
• time scale very small relativ to source acitivty
  
• only one event per source

13
GenSyn deployments

• Free, non-commercial licence http//www.item.ntnu
  .no/poulh/GenSyn/gensyn.html(approx 50
  licencees around the world)
• Education
• Lab in TTM4150 Internet Protocols
• Research
• Project and master works, e.g. WLAN monitoring
• Intrusiveness of active testing
• Delay estimation
• Flow sampling
• Field trials
• QoS and OSS testing in FSN field trial
• Telenor Discman Testbed (EURESCOM)
• M3I (EU IST) pricing models

14
GenSyn model extensions

• Editor for creating and changing models added
• Extensions of model library
• P2p-applications, e.g. BitTorrent (current work)
• Distributed games (planned)
• Extended measurement functionality
• Conflicts with Java
• Redesign and reimplement

15
GenSyn on traffic generator lists

• Henning Schulzrinne http//www.cs.columbia.edu/h
  gs/internet/traffic-generator.html
• Univ. Napoli http//www.grid.unina.it/software/I
  TG/link.php
• Sally Floydhttp//www.icir.org/models/trafficgene
  rators.html