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Understanding the AM API using Named Data Networking

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4 Wait for resources to be ready

You can tell whether your nodes are ready by using a script built on omni called readyToLogin.

  1. Please use the command:
    readyToLogin -a AM_NICKNAME LabOne 
    where (as before) AM_NICKNAME and LabOne are your aggregate 
    manager nickname and your slice name (both found on your worksheet). 
  2. If it reports that the sliver is not yet ready (for example, it might say that the status is "changing"), then wait a minute or two and try again. Once everything is complete, readyToLogin will give output that should look something like this:
    rschr's geni_status is: ready (am_status:ready)  
    User example logs in to rschr using: 
            ssh  -p 32768 -i /Users/example/.ssh/geni_key_portal 
    User example logs in to collar using: 
            ssh -p 32769 -i /Users/example/.ssh/geni_key_portal 

5 Trying out the NDN application

In this experiment, you will be able to see the NDN in-network caching in action. Our experiment consists of the following nodes:

  • A data source node, called Custodian that holds data in the namespace /nytimes
  • A internet router node, called Internet that forwards Interest and Data packets to and from the Custodian.
  • A university hub node, called University that forwards Interest and Data packets to and from the university nodes.
  • A principal investigator node, called PI and a experimenter node, called Experimenter that will send Interest requests to the Custodian via UDP tunnels.

Download the scripts and Python codes to your computer and extract it.

Or alternatively,

$ wget
$ tar -xvf ndn-tutorial.gz

In the configuration file, edit the fields according to your GENI username, SSH key, GENI Aggregate name, pc and port numbers. Keep the quotes format unchanged, otherwise the script may not run.

Run, this will automatically transfer the necessary files to the nodes in our topology.

$ ./

Login into the node Custodian and start the NDN Forwarding Daemon (NFD),

$ nfd-start 

wait until the shell prompt returns (~ a few seconds). The NFD is now up and running.

5.1 Run the NDN application on the same node

You are now ready to start the producer application and register a namespace. (note: you can try other namespaces as well)

$ python -n /nytimes 

You should see a message

$ Registering prefix /nytimes 

Open another terminal on the custodian node and run

$ python -u /nytimes/science

This will start the consumer application that will send Interest request packets to the producer. Take a moment to look at the entries in the NFD. You are all set. Stop the producer application by Ctrl + C and stop the NFD

$ nfd-stop

5.2 Run the NDN application on the entire topology

For this section, we are going to start the NFD in all nodes and register the namespace. We automated these tasks for the University and Internet nodes using a script. On your computer, run

$ ./

You should see NFD being started on the nodes.

SSH to the Custodian node and start the producer application

$ nfd-start
$ python -n /nytimes 

SSH to the Experimenter node, register the namespace, and start the consumer application

$ nfdc register / udp4://
$ python -u /nytimes/science

This time the Interest request travels the entire topology, leaving breadcrumbs. The Data packet follows the breadcrumbs back to the consumer, leaving cached versions of the content. This is call in-network caching and it is one of the most important features in Information Centric Networking (ICN) You can check this phenomenon by running the same consumer application in the PI node. SSH to the PI node, register the namespace, and start the consumer application

$ nfdc register / udp4://
$ python -u /nytimes/science

This time your PI node gets the content back, but nothing happens on the Custodian because the requested content is cached in the University node. You can repeat the experiment with different namespaces

$ python -u /nytimes/math

This time you see that the Interest request is served by the Custodian.

5.3 (Optional) Visualize experiment data flows

To use the GENI Desktop to visualize the data flows in your network, continue with the instructions here.


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