dce-cradle-usecase-1.rst

DCE Cradle Use-case 1

This tutorial document describes what |dce_cradle| is, how we can use it, how we extend it.

Team:

Hajime Tazaki, Frederic Urbani, Thierry Turletti

Key Result(s):

TCP goodput performance in |dce_cradle| shows similar results with real network configuration and software on Linux.

Source(s):

The paper describing this text was submitted to Workshop on ns-3 2013 (under review).

Contacts:

Hajime Tazaki (tazaki at nict.go.jp)

Introduction:

|dce_cradle| allows us to use ns-3 native application with Linux kerne as a network stack. The key question is: how different/similar |dce_cradle| behaves ? This tutorial tries to answer this question with showing TCP goodput performance.

Methods:

We need to prepare the following simulation codes to conduct the experiment.

• ns-3-dev
• ns-3-dce
• ns-3-linux
• Network Simulation Cradle (NSC)
• |dce_cradle| patch
• iperf
• Linux TC (packet loss and delay injection)

Results:

While the experimentation with ns-3 native TCP stack shows about 83% less bandwidth than with the real environment, NSC and |dce_cradle| obtain more realistic performance (only 25-30% less bandwidth than with the real environment) under the simple dumbbel topology scenario.

(News) If we changed the default variables of |ns3| TCP stack as follows, the result of goodput has improved.

Config::SetDefault ("ns3::TcpSocket::SegmentSize", UintegerValue (1448));
Config::SetDefault ("ns3::TcpSocket::DelAckCount", UintegerValue (1));

Instructions to Replicate This Experiment:

1. Experiment on ns-3

   1. Setup ns-3-dce

      % mkdir dce-cradle-test
      % cd dce-cradle-test
      % hg clone -r 327 http://code.nsnam.org/furbani/ns-3-dce
      % ./utils/clone_and_compile_ns3_dce.sh
      

      for more information, see the DCE documentation.

   2. patch |dce_cradle| extension

      % cd dce-cradle-test
      % wget https://codereview.appspot.com/download/issue6856090_7001.diff
      % cd ns-3-dce
      % patch -p1 < ../issue6856090_7001.diff
      % ./waf
      % ./waf install
      

   3. prepare Network Simulation Cradle

      % cd dce-cradle-test
      % wget http://research.wand.net.nz/software/nsc/nsc-0.5.3.tar.bz2
      % tar xfj nsc-0.5.3.tar.bz2
      % mv nsc-0.5.3 nsc
      % cd nsc
      % ./scons.py
      % cp lib/liblinux2.6.26.so ../build/lib/
      % cd ..
      % cd ns-3-dev
      % /waf configure --prefix=`pwd`/../build --with-nsc=../nsc
      % ./waf
      % ./waf install
      

   4. run a script

      .. literalinclude:: dce-cradle-test.sh
        :emphasize-lines: 20
        :linenos:
        :lines: 1-24, 40-
      
      

2. Experiment on Linux real network

   1. prepare dumbbell topology

      node1              node5
          \              /
         node3 ======== node4
          /              \
      node2              node6
      

   2. configure bottleneck link

      at node3, packet loss and delay are configured with tc.

      sudo tc qdisc add dev eth0 root handle 1:0 tbf limit 15Kb buffer 10Kb/8 rate 2Mbit
      sudo tc qdisc add dev eth0 parent 1:0 handle 10: netem delay 100ms loss 5%
      sudo sysctl -w net.ipv4.ip_forward=1
      

      at node4, packet loss and delay are configured with tc as well.

      sudo tc qdisc add dev eth0 root handle 1:0 tbf limit 15Kb buffer 10Kb/8 rate 2Mbit
      sudo tc qdisc add dev eth0 parent 1:0 handle 10: netem delay 100ms loss 5%
      sudo sysctl -w net.ipv4.ip_forward=1
      

   3. run a script at node1

      .. literalinclude:: iperf-dumbbell.sh
        :linenos:
        :lines: 1-5,9-16,26-37,43-
      
      

3. Plot the results of above experiment

   1. run a script

      You can gather the text outputs from the above experiments and plot the figure with gnuplot.

      .. literalinclude:: dce-cradle-gnuplot.sh
            :linenos:
            :lines: 1-38