• Technical University of Cluj-Napoca
WAN Emulator Software Tool
Andrei Bogdan Rus, Virgil Dobrota, René Serral Gracià, Jordi Domingo-Pascual
TD(08)006The 11th COST 290 MC Meeting
Tampere University of Technology (TUT), Finland, May 27 – 28, 2008
31 August 2008 2TUCN
Outlines
• Introduction• WAN Emulator capabilities• Testbed architecture• Implementing a scenario• iptables
• tc tool• OWAMP Testing Tool • Tests and Results• Conclusions and Further Work
31 August 2008 3TUCN
Introduction
• Testing a protocol/ application in real life condition
is not an easy task involves expensive hardware or proprietary solutions
• Linux offers a tool called NetEma component of tc with good performance but difficult to use
31 August 2008 4TUCN
WAN Emulator capabilities (1/2)
• WANE (WAN Emulator)has a friendly user interface, while maintaining the good performance in evaluations
• Emulated parameters: delay, jitter, dropped packets and duplicate packetsThroughput from a minimum value up to the maximum hardware transfer rate
31 August 2008 5TUCN
WAN Emulator capabilities (2/2)
• Emulate several scenarios in the same time for different data flows
• Flows are differentiated by:source/destination IP address, mask and portprotocol (TCP, UDP or ICMP)
WAN Emulator
Scenario 1
Scenario 2
Scenario N
FLOW 1
FLOW 2
FLOW N
FLOW 1
FLOW 2
FLOW N
31 August 2008 6TUCN
Testbed architecture
• Routing PC -> Linux machine with forwarding capabilities
31 August 2008 7TUCN
Implementing a scenario
• Marking the specific traffic flow using iptables
• Building the tc tree composed by queuing disciplines with the tc tool
• Filtering the flows with a specific mark and sending them to a specific branch from the tc tree, using the filtering option of tc
Steps covered by WANE when implementing a scenario
31 August 2008 8TUCN
iptables (1/2)
• Native packet filtering mechanism for the Linux 2.4 and above kernel series
filter packetsimplement network address translation mangle packets
31 August 2008 9TUCN
iptables (2/2)
• Three tables:filternatmangle
• Five chainsPREROUTINGINPUTOUTPUTFORWARDPOSTROUTING
Mar
king
pa
cket
s
31 August 2008 10TUCN
tc tool (1/2)
• Efficient and flexible software tool, implemented in Linux kernels
• Based on the concept of queue, where the binary data is stored, before being sent to the network interface
• DISADVANTAGES -> complex to work with
31 August 2008 11TUCN
tc tool (2/2)
• Position of tc queuing disciplines within TCP/IP stack
• Types of queuing disciplines:
ClassfulClassless
31 August 2008 12TUCN
tc tree
• HTB qdisc used to limit the maximum transfer rate for the data flow
• NetEm qdisc are emulating the IP traffic parameters like:
packet delaysdropped packetsduplicate packets
31 August 2008 13TUCN
OWAMP Testing Tool (1/2)
• Used to test the performance of WANE
• Measures unidirectional characteristics such as:one-way delayone-way loss one-way duplications
31 August 2008 14TUCN
OWAMP Testing Tool (1/2)
• High-precision measurement of these one-way IP performance metrics needed good time synchronization
31 August 2008 15TUCN
Tests and ResultsDelay tests (1/3)
31 August 2008 16TUCN
Tests and ResultsDelay tests (2/3)
• Gaussian Distribution
31 August 2008 17TUCN
Tests and ResultsDelay tests (3/3)
• Pareto Distribution
31 August 2008 18TUCN
Tests and ResultsPackets Dropped
9089.890.190.39080.479.779.680.18069.870.369.970.47060.360.259.659.76050.149.849.250.25039.840.140.839.14030.230.230.429.53019.919.920.220.32010.19.810.19.810
1MB/s [%]
100kB/s [%]
10kB/s [%]
1kB/s [%]
Measured value at:Value
imposed by WANE [%]
Difference between imposed values of dropped packets and the measured ones was lessthan 1%
31 August 2008 19TUCN
Tests and ResultsDuplicate Packets
Difference between imposed values of duplicate packets and the measured ones was lessthan 1%90.290.190.290.190
79.980.279.880.28069.969.969.769.87060.160.160.360.26050.249.849.850.15039.840.339.940.64029.930.130.229.53020.219.82019.62010.19.710.110.310
1MB/s [%]
100kB/s [%]
10kB/s [%]
1kB/s [%]
Measured value at:Value
imposed by WANE [%]
31 August 2008 20TUCN
Tests and ResultsMaximum throughput
4.0595.95 [Mbps]100 [Mbps]4.2247.89 [Mbps]50 [Mbps]4.209.58 [Mbps]10 [Mbps]4.204.79 [Mbps]5 [Mbps]5.000.95 [Mbps]1 [Mbps]4.17479.17 [kbps]500 [kbps]2.6797.33 [kbps]100 [kbps]3.8948.06 [kbps]50 [kbps]4.109.59 [kbps]10 [kbps]
Error [%]Average throughput measured
Maximum throughput imposed by WANE
31 August 2008 21TUCN
Conclusions and Further Work
• WANE (WAN Emulator) made the job easier for the researchers because they will not have to bother with creating the tc tree, marking the specific traffic and filtering it.
• As future work, we want to improve WANE in order to support IPv6 traffic. Additionally we envisage an extra feature of the emulator to be able to corrupt packets and to test how this could influence the quality of the tested flow
31 August 2008 22TUCN
Thank You
