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EXPERIMENTS.md

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Experiments

Mini-NDN includes an experimentation framework which allows a user to create and automate networking experiments. Users can run existing experiments, included with Mini-NDN, or define their own custom experiment.

Running existing experiments

Mini-NDN includes three example experiments that can be used to test the network or as reference for custom experiment implementations. ndn-tools must be installed to run the example experiments as each experiment uses both ndnpingserver and ndnping. Please see INSTALL.md for instructions on installing ndn-tools.

To see a list of the available experiments, run Mini-NDN using the --list-experiments parameter:

minindn --list-experiments

To run an experiment, provide the experiment name as an argument to the --experiment parameter:

sudo minindn --experiment=pingall

Each experiment will run until completion or exit if there is an error setting up the test environment.

The three included experiments are set up using the same starting configuration. Each node runs NFD, NLSR, and an ndnpingserver which advertises the node's site name. After a waiting period to allow the network to converge (default is 60 seconds), the convergence status of the network is checked. If each node's FIB does not have an entry for every other node's router name and advertised prefix, the experiment is aborted and an error is reported.

Common experiment parameters

The time allowed for convergence (in seconds) can be configured using the --ctime parameter:

sudo minindn --ctime=30 ...

After the experiment has finished running, the command-line interface (CLI) will be launched and the user can then interact with the test environment. To disable the CLI and instead exit Mini-NDN as soon as the experiment has finished, use the --no-cli parameter:

sudo minindn --no-cli ...

The included experiments are described in detail below along with additional parameters that can be provided to modify the execution of the experiments.

Pingall experiment

Scenario: Each node in the network simultaneously pings every other node in the network at a one second interval.

Experiment ID: --pingall

The number of pings sent in the experiment can be configured using the --nPings parameter:

sudo minindn --experiment=pingall --nPings=120

By default, --nPings is 300 for the Pingall experiment.

Failure experiment

Scenario: Each node in the network simultaneously pings every other node in the network at a one second interval. After 60 seconds, the node with the name "csu" is brought down. The node is left in a failed state for 120 seconds while the other nodes continue pinging. After this period, the failed node is recovered and pings are collected for an additional 90 seconds.

Experiment ID: --failure

--nPings is 300 for the Failure experiment and cannot be modified.

Multiple failure experiment

Scenario: Each node in the network simultaneously pings every other node in the network at a one second interval. After 60 seconds, the first node in the network will be brought down and remain in failed state for 60 seconds. After the failure period, the node is recovered and the network is allowed to recover for 60 seconds. After the recovery period, the next node will go through this failure and recovery process. Once every node in the network has gone through the failure and recovery process, the experiment will end.

Experiment ID: --multiple-failure

--nPings is dependent on the size of the topology being tested. 120 pings are scheduled for each node's failure/recovery period as well as an additional 60 pings for the initial collection period.

Creating custom experiments

Mini-NDN provides a simple Python based framework which allows a user to define their own experiment and run it from the command line.

To create an experiment, follow these steps:

  1. Create a Python source file for the experiment in the ndn/experiments directory.

    e.g.) ndn/experiments/example.py

  2. Derive the experiment from the Experiment base class defined in ndn/experiments/experiment.py.

     #!/usr/bin/python

 from ndn.experiments.experiment import Experiment

 class ExampleExperiment(Experiment):
     def __init__(self, args):
         Experiment.__init__(self, args)

  3. Override the setup() method to define how the experiment should be initialized

    e.g.) Run an ndnping server in the background on each node

     def setup(self):
    for host in self.net.hosts:
        host.cmd("ndnpingserver host.name &")

  4. Override the run() method to define how the experiment should behave

    e.g.) Obtain the NFD status of each node and save it to file

     def run(self):
     for host in self.net.hosts:
         host.cmd("nfd-status > status.txt")

  5. Register the experiment with the ExperimentManager to make the experiment runnable from the command line.

     Experiment.register("example-name", ExampleExperiment)

The experiment can then be run from the command-line using the name registered. "example-name" in the above example:

    sudo minindn --experiment=example-name

Full example experiment code

#!/usr/bin/python

from ndn.experiments.experiment import Experiment

class ExampleExperiment(Experiment):
    def __init__(self, args):
        Experiment.__init__(self, args)

    def setup(self):
        for host in self.net.hosts:
            host.cmd("ndnpingserver host.name &")

    def run(self):
        for host in self.net.hosts:
            host.cmd("nfd-status > status.txt")

Experiment.register("example-name", ExampleExperiment)