Post on 03-Feb-2018
transcript
• 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
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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
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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
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Testbed architecture
• Routing PC -> Linux machine with forwarding capabilities
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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
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iptables (1/2)
• Native packet filtering mechanism for the Linux 2.4 and above kernel series
filter packetsimplement network address translation mangle packets
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iptables (2/2)
• Three tables:filternatmangle
• Five chainsPREROUTINGINPUTOUTPUTFORWARDPOSTROUTING
Mar
king
pa
cket
s
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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
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tc tool (2/2)
• Position of tc queuing disciplines within TCP/IP stack
• Types of queuing disciplines:
ClassfulClassless
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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
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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
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OWAMP Testing Tool (1/2)
• High-precision measurement of these one-way IP performance metrics needed good time synchronization
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Tests and ResultsDelay tests (1/3)
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Tests and ResultsDelay tests (2/3)
• Gaussian Distribution
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Tests and ResultsDelay tests (3/3)
• Pareto Distribution
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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%
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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 [%]
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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
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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
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Thank You