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Simple Layer 2 GENI Experiment

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4. Configure and Initialize

Now that you have reserved your resources, you are ready to run your first GENI experiment. For the purpose of this tutorial we are going to do a simple layer 2 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.
    ExoGENI If you are using an ExoGENI rack and don't see the ssh link, wait for the background to turn green and then refresh the drawing by clicking the "refresh" button next to the "Submit" button at the bottom of the page. Now try to log in again.
  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):
Login information for a VM
Figure 9-1 Login to a VM.

4.2 Download and compile experiment software

  1. In the first terminal, download the pingPlus software:
  2. Decompress the pingPlus software:
    tar xvfz pingPlus-0.2.tar.gz
  3. If you are using an ExoGENI rack, first install the compiler.
    apt-get update
    apt-get install build-essential
    InstaGENI The default image on the InstaGENI rack already includes a C compiler.
  4. Compile the pingPlus software.
    cd pingPlus-0.2
  5. Your output should look like this:
    client:~% wget
    --2013-07-05 09:32:26--
    Resolving (
    Connecting to (||:80... connected.
    HTTP request sent, awaiting response... 200 OK
    Length: 4726 (4.6K) [application/x-gzip]
    Saving to: `pingPlus-0.2.tar.gz'
    100%[================================================================================================================================================================>] 4,726       --.-K/s   in 0.07s
    2013-07-05 09:32:27 (69.1 KB/s) - `pingPlus-0.2.tar.gz' saved [4726/4726]
    client:~% tar xvfz pingPlus-0.2.tar.gz
    client:~% cd pin
    pingPlus-0.2/        pingPlus-0.2.tar.gz
    client:~% cd pingPlus-0.2
    client:~/pingPlus-0.2% make
    gcc    -c -o packetFunctions.o packetFunctions.c
    gcc    -c -o pingPlusListener.o pingPlusListener.c
    gcc  packetFunctions.o pingPlusListener.o  -o pingPlusListener
    gcc    -c -o pingPlus.o pingPlus.c
    gcc  packetFunctions.o pingPlus.o -o pingPlus
  1. Repeat the above in the second terminal.

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. For InstaGENI nodes, add /sbin to the PATH:
    setenv PATH $PATH\:/sbin
    InstaGENI For InstaGENI resources, the PATH on the default image does not include /sbin
  2. Check the interfaces of your nodes. In the terminal type:
    You should see at least two interfaces:
    • The control interface. This is the interface you use to access the node, e.g. ssh into your host. The control interface is mainly used for control traffic, i.e. traffic for controlling the node and the experiment.
    • The data interface. This is the interface that is used for sending experimental traffic. This is the interface that connects to the other hosts of your experiment through GENI. The links between these interfaces are the ones that allow you to run non-IP experiments. The data interface is the one that has an IP address and mask that match what you configured before you reserved your resources.
  3. Fill in the worksheet, noting the name and IP address of the control and of the data interfaces for each node.
    InstaGENI For InstaGENI resources, the command prompt on each node says "client" or "server" respectively.
  4. From the client, ping the server. From the terminal window that is logged in to the client type :
        ping <server data IP addr> -c 5
    For example:
        ping -c 5
    An example output should look like :
    [sedwards@client ~]$ ping -c 5
    PING ( 56(84) bytes of data.
    64 bytes from icmp_req=1 ttl=64 time=183 ms
    64 bytes from icmp_req=2 ttl=64 time=91.2 ms
    64 bytes from icmp_req=3 ttl=64 time=91.1 ms
    64 bytes from icmp_req=4 ttl=64 time=91.1 ms
    64 bytes from icmp_req=5 ttl=64 time=91.2 ms
    --- ping statistics ---
    5 packets transmitted, 5 received, 0% packet loss, time 4004ms
    rtt min/avg/max/mdev = 91.156/109.579/183.129/36.775 ms

5.1 Send non-IP traffic

GENI provides the capability of running non-IP experiments, since you can connect your hosts at Layer 2. For the purpose of this tutorial we will use a very simple Layer 2 ping program that sends packets using a custom ethernet type.

  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.
    service neuca stop
    ExoGENI The ExoGENI "neuca" service controls a variety of network configuration details.
  2. Disable the IP on both of your nodes (being careful to disable IP on the data interface NOT the control interface). In each of the terminals type:
      sudo ifconfig <data interface name>
    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.
    ExoGENI On ExoGENI nodes, you are already running as root, so don't include sudo in the command.
  3. Try again to ping from the client to the server. In the terminal window of the client type:
        ping <server data IP addr> -c 5
    For example:
        ping -c 5
    This time the ping should timeout.
  4. Start the Layer 2 ping server. In the server terminal window, type:
      sudo ~/pingPlus-0.2/pingPlusListener <EtherType from worksheet>
  5. From the client try to ping the server at layer 2. You will need the mac address of the data interface of the server, the name of the data interface of the client, and the EtherType from your worksheet. In the terminal window of the client, type:
    sudo ~/pingPlus-0.2/pingPlus <server mac> <client i/f name> <EtherType>
    where <server mac> is the server's data interface's MAC address, 
    <client i/f name> is the client data interface's name, and
    <EtherType> is the EtherType from the worksheet.
    The result should look like :
    $ sudo ~/pingPlus-0.2/pingPlus 02:00:9B:48:3E:20 eth3742 10001
    RQ:'5582+2067' to 2:0:9b:48:3e:20.
    RL:5582+2067 from 2:0:3e:15:6c:ab.

6. Analyze Experiment

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

6.1 Logout of your nodes

  • When you are done, CTRL-C in the server window to stop PingPlusListener.
  • Then type exit in each of your open terminals.

Congratulations you have run a Layer 2 experiment in GENI!


Next: Finish