wiki:GENIExperimenter/Tutorials/jacks/GettingStarted_PartI/Procedure/Execute

Version 10 (modified by rrhain@bbn.com, 5 years ago) (diff)

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Lab Zero: A First Experiment Using GENI

Image Map

4. Configure and Initialize

Now that you have reserved your resources, you are ready to run your first GENI experiment.

4.1 Login to nodes

  1. To get login information for a VM, again click on the "slice page" link.
  2. This wil bring you to the slice page and you can click on the "Details" button in your aggregate rectangle.
To ssh from Windows machines, you must launch an ssh client and enter in the relevant information:
Tip To ssh from the command line on unix-based machines, do the following (substituting the values shown on the screen):
ssh USERNAME@HOSTNAME -p PORT
Login information for a VM
Figure 4-1 Login to a VM.

5. Execute Experiment

5.1 Send IP traffic

The first simple experiment that we will run is to verify the IP connectivity between our hosts.

  1. Check the interfaces of your nodes. In the terminal type:
       sudo ifconfig
    
    You should see at least two interfaces:
    • The control interface. This is the interface you use to access the node, e.g. ssh into your host. The control interface is mainly used for control traffic, i.e. traffic for controlling the node and the experiment.
    • The data interface. This is the interface that is used for sending experimental traffic. This is the interface that connects to the other hosts of your experiment through GENI. The links between these interfaces are the ones that allow you to run non-IP experiments. The data interface is the one that has an IP address and mask that match what you configured before you reserved your resources.
  2. Fill in the worksheet, noting the name and IP address of the control and of the data interfaces for each node.
    Tip The command prompt on each node says "client" or "server" respectively.
  3. From the client, ping the server data plane interface. From the terminal window that is logged in to the client type :
        ping <server data IP addr> -c 5
    
    For example:
        ping 10.1.1.2 -c 5
    
  4. Now, ping the server control plane interface. From the terminal window that is logged in to the client type :
        ping <server control IP addr> -c 5
    
    For example:
        ping 172.17.1.9  -c 5
    

5.2 Install and use iperf

  1. Install the iperf software on both nodes, by running the appropriate command below.
InstaGENI If you are using resources at an InstaGENI aggregate do:
    sudo yum install iperf
ExoGENI If you are using resources at an ExoGENI aggregate do:
    sudo apt-get install iperf
    hash
  1. Start an iperf server on the server node:
        iperf -s
    
  2. Run an iperf client via the data plane:
        iperf -c <server data IP addr>
    
    For example:
        iperf -c 10.1.1.2
    

What is the bandwidth of this link?

Why?

  1. Run an iperf client via the control plane:
    iperf -c <server control IP addr>
    
    For example:
    iperf -c 172.17.2.2
    

What is the bandwidth of this link?

Why?

  1. Type CTRL-C on the server node to stop the iperf server.

5.3 Bring down the server's data interface

  1. ExoGENI nodes run a service called "neuca" that managed network interfaces on the node. To manually adjust the IP address, we must first disable neuca on both nodes.
    sudo service neuca stop
    
    ExoGENI The ExoGENI "neuca" service controls a variety of network configuration details.
  2. From the client node, start pinging the server data plane interface:
        ping <server data IP addr> 
    
  3. On the server node, bring down the data plane interface (being careful to disable the data interface NOT the control interface):
        sudo ifconfig <server data interface name> down
    

After you bring down the data interface, the pings should indicate that the destination is unreachable.

Why?

Warning Be extra careful to disable the IP on the data interface, bringing down the IP on the control interface means that you will lose connectivity to your host.

5.4 Bring down the server's control interface

  1. From the client node, start pinging the server control plane interface:
        ping <server control IP addr>
    
  2. From the server node, bring down the control plane interface and try to ping it from the client node:
        sudo ifconfig <server control interface name> down
    

Your ssh session should immediately hang.

Why?

After you bring down the control interface, the pings should indicate that the destination is unreachable. Why?

Tip Unfortunately, in order to recover from a situation like this where you've lost the ability to login to your nodes, the only way to recover is to delete your resources and start again.

6. Analyze Experiment

Now is when you would ordinarily analyze the results of your experiment.

6.1 Logout of your nodes

  • Then type exit in your open terminal.

Congratulations you have run an experiment in GENI!


Setup

Next: Finish