wiki:GENIExperimenter/Tutorials/GettingStarted_PartI/Procedure/Execute

Version 15 (modified by sedwards@bbn.com, 6 years ago) (diff)

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This is a working draft.

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 login to a VM, again click the i in the circle.
  2. Now, click on the ssh link. If you have installed FireSSH a new tab will open up.
  3. In the window that will pop up :
    • in the password field type in your passphrase
    • for the private key, browse to the file that has your private key
    • Press OK
  4. Repeat the previous step for the second VM.
Tip To ssh from the command line, 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 10.17.1.2 -c 5
    
  1. 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 Take down the 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. On the server node, bring down the data plane interface (being careful to disable the data interface NOT the control interface):
        sudo /sbin/ifconfig <server data interface name> down
    
  3. From the client node, try to ping the server data plane interface:
        ping <server data IP addr> -c 5
    

This time the ping 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.

5.3 Bring down the control interface

  1. From the server node, bring down the control plane interface and try to ping it from the client node:
        sudo /sbin/ifconfig <server control interface name> down
    

Your ssh session should immediately hang.

Why?

  1. From the client node, try to ping the server control plane interface:
        ping <server control IP addr> -c 5
    

What happens? 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!


Introduction

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