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Understanding the AM API using Named Data Networking
4 Wait for resources to be ready
You can tell whether your nodes are ready by using a script built on omni
called readyToLogin
.
-
Please use the command:
readyToLogin -a AM_NICKNAME SLICE_NAME
where (as before) AM_NICKNAME and SLICE_NAME are your aggregate manager nickname and your slice name.
- 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 example@pc1.utah.geniracks.net User example logs in to collar using: ssh -p 32769 -i /Users/example/.ssh/geni_key_portal example@pc1.utah.geniracks.net ...
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 node, called
Internet Router
that forwardsInterest
andData
packets to and from theCustodian
. - A node, called
Campus Router
that forwardsInterest
andData
packets to and from the university nodes. - A principal investigator node, called
PI
and a experimenter node, calledExperimenter
that will sendInterest
requests to theCustodian
via UDP tunnels.
Download the scripts and Python codes to your host machine and extract it.
Or alternatively,
$ wget http://192.1.242.151/files/ndn-tutorial.gz $ tar -xvf ndn-tutorial.gz
In the ndn-tutorial-config.sh 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.
Once the topology is up, run copy-scripts.sh
, this will automatically transfer the necessary files to the nodes in our topology.
$ ./copy-scripts.sh
Login into the node Custodian
and re-start the NDN Forwarding Daemon (NFD). This will make sure the content store is refreshed and the routes are cleared.
$ nfd-stop $ 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)
The producer application will listen for Interest
requests of a namespace -n
and reply with Data
packets.
$ cd /local $ python producer.py -n /nytimes
You should see a message
$ Registering prefix /nytimes
Open another terminal on the Custodian
node and run
$ cd /local $ python consumer.py -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
In this section, we are going to start the NFD and register the forwarding faces on the remaining nodes. We have automated these tasks for the Campus-Router
, Internet-Router
, and PI
nodes using a script. On your host machine, do the following:
$ ./setup-app.sh
We are now ready to run our experiment.
SSH to the Custodian
node and start the producer
application
$ python producer.py -n /nytimes
SSH to the Experimenter
node, and start the consumer application
$ python consumer.py -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 and start the consumer application
$ python consumer.py -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 Campus Router
node.
You can repeat the experiment with different namespaces
$ python consumer.py -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.