The ONL Tutorial

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The Remote Laboratory Interface

We present an example using one NSP since most fundamental concepts can be explored using a 1-NSP configuration. Also, course work typically uses a single NSP so as to allow more concurrent testbed users.

A few comments before we begin:

• You can define a configuration of NSPs using the RLI without connecting to the ONL testbed.

  This approach of defining the experiment configuration while disconnected from the testbed will help you reduce setup errors by giving you time to reflect on your choices. Furthermore, it will improve resource usage efficiency during testbed busy periods.

• You should have already followed the directions given by the Getting Started link in sidebar of the ONL Web site.
• Typically, you will have made an advanced resource reservation through the ONL Web page. But the example shows how this can be done through the RLI.
• We have not included screen shots of logging into the ONL user host onlusr since there are a plethora of tools. But here are a few comments:
  • We use a password-free SSH approach described in Tutorial => Summary Information => Password-Free SSH.
  • The screen shots in the examples were captured while running Windows XP, and we used the PuTTY tool for enterring commands. Many of us actually use Linux or Windows XP with Xterms, but that is a personal choice.
• You may (or may not) encounter some problems with printing this web page because of the large number of images. We have not found any automated reliable method to avoid vertical compression of images that fall on a page boundary.

Steps (In Brief)

Here are the major steps in this example:

1. Create the SSH tunnel required by the RLI
2. Start the RLI on your client host
3. Add a cluster to the experiment
4. Make a reservation for 1 hour
5. Commit the experiment
6. Set up default routing at each port
7. Monitor the bandwidth at ingress port 2
8. Monitor the bandwidth at egress port 3
9. Rescale the bandwidth display
10. Move a group of icons
11. Reconfigure one NSP to emulate a dumbbell topology

Steps (In Detail)

1. Create the SSH tunnel required by the RLI

   See the Getting Started link in the sidebar of the ONL Web page. This step is not required if you do not plan to commit your experiment or make a resource reservation through the RLI.

2. Start the RLI on your client host

   Typically, this is either done through the command java -jar RLI.jar or by double-clicking on the Desktop RLI icon.


3. Add a cluster to the experiment
• Select Topology => Add Cluster


4. Make a Reservation for 1 hour

   This step is unnecessary if you already made a reservation through the ONL Web page and is only useful if the testbed is not being heavily used.

• Select File => Make Reservation.
• Fill in the reservation duration in the Make Reservation window.

  A dialogue box titled "Log In" will appear.



• Enter your User Name and Password in the dialogue box.



• A status message will appear in a Reservation popup window once the reservation has been processed.


5. Commit the experiment: Select File => Commit
• The red Commit Needed box should disappear and the progress bar should show the text "Committing"

• (Optional) You can observe the progress of the allocation and initialization process through the ONL Web page.

If the information is accepted by the ONL resource daemon, resource allocation and initialization will commence. The initialization of NSPs and hosts takes a few minutes. Minor changes such as changing a routing table occur almost instanteously. You can observe the progress of the allocation and initialization process through the Testbed Status link in the sidebar of the ONL Web page.



• After a few minutes when the hosts have been reinitialized, the host icons will darken.
• The commit should complete in about 5 minutes. Dashed lines will change to solid ones; all components will be dark; and the progress bar will show a "Commit Completed" message.


6. Set up default routing at each port

• Right click on the n1p2 icon to get name of the external interface (onl32.arl.wustl.edu in this example)
• Ssh to onl.arl.wustl.edu

You will actually end up on the ONL user host onlusr.arl.wustl.edu.

• From the host onlusr, ssh to the external interface of the host assigned to n1p2

The example shows that the external network interface is onl32.arl.wustl.edu (onl32 is an alternate name).



• Ping the n1p3 interface from the n1p2 host


Note that the ping command failed because the NSP's routing tables are empty. Since the target of the ping command refers to the internal network interface n1p3, the host attempts to send the ping packets over the internal network interface which is associated with the name n1p2 and the IP address 192.168.1.48. This internal interface is connected to the ingress-side of port 2 of the NSP. When a packet reaches the port, it will be dropped because there will be no route matching the packets destination IP address.

• Look at the routing table at port 2 to verify that it is really empty:
  Select Port 2 => Configuration => Route Table


• Install default route table entries at all ingress ports
• Select Topology => Generate Default Routes
• Select File => Commit



• Look at the routing table at port 2 to verify that it now contains a default routing table:
  Select Port 2 => Configuration => Route Table


• Notice that the ping command now succeeds starting at packet number 66.


7. Monitor the bandwidth at ingress port 2

• Select Add Monitor Display from the Monitoring window and type "bandwidth" into the popup window.

  A new window titled "bandwidth" will appear. The bandwidth will be charted here.



• In the bandwidth window: Select Add Parameter
• In the RLI window: Select Port 2 => Monitoring => Ingress => Port Bandwidth
• In the Add Parameter window: Enter 0.3 in the Enter Polling Rate dialogue box.



In most situations, polling once per second will show sufficient detail. If we polled once per second with ping traffic (one packet per second), the bandwidth chart would appear as a horizontal line. But by polling once every 0.3 seconds, the bandwidth chart will show spikes occuring once per second.


• "IPPBW 2" (Input Port Processor BandWidth 2) will be added to the legend and a line should appear. The figure (right) shows the case when the ping command is started after the bandwidth window has been opened. Double clicking on the name in the legend will allow you to change the name and give a fuller description of the parameter. Note: You do not need to do a commit to do any charting operations.


8. Monitor the bandwidth at egress port 3 (Not Shown)

   Follow the same steps to add port 3's egress bandwidth to the bandwidth chart.

   • bandwidth window: Select Add Parameter
   • RLI window: Select Port 2 => Monitoring => Egress => Port Bandwidth
   • Add Parameter window: Enter 0.3 in the Enter Polling Rate dialogue box.
9. Rescale the bandwidth display

The appearance of the previous bandwidth chart can be modified to reveal more of the ping-like behavior: bandwidth spikes appearing approximately once per second. The charting features of the RLI allow the user to focus on a portion of a chart by effectively zooming in and out along both the x- and y-axes.


• Left-clicking the y-axis at point Y zooms in so that the topmost y-value is Y.


• Left-clicking the x-axis at point X zooms in so that the rightmost x-value is X and also freezes the chart so that new values are not displayed. Dragging the x-axis slider to the far right resumes the display of new values.


• Zooming in on a window can also be done through the menu item View => Zoom In From Selection.
• You can zoom out by left-clicking on the arrowhead of the x-axis or the y-axis.
10. Move a group of icons


Single icons can be moved by grabbing it and dragging it to a desired location. A group of icons can be dragged by first selecting a group of icons by enclosing the icons in a rectangle defined by dragging the cursor with the left mouse button, and then dragging one of the grouped icons.



11. Reconfigure one NSP to emulate a dumbbell topology

A 2-router dumbbell configuration is used in many congestion experiments. Although two NSPs can be used to construct a dumbbell topology, a smaller version can be constructed from a single NSP by creating a link between two ports. The following steps creates a link between ports 6 and 7 and changes the routing table at port 2 so that ping packets from n1p2 will go into port 2, out of port 7, into port 6, and out of port 3 to n1p3. The return packet will still travel from n1p3 into port 3 where it will travel directly to port 2 and then out of port 2 to n1p2.


• Select Topology => Add Link
• Drag the cursor with the left mouse button from port 7 to port 6 (or port 6 to port 7)

A dashed link will appear between the 2 ports.

• Select File => Commit

  The link between ports 7 and 6 will turn solid when the link has been actually created.




Now we need to change the routing table at port 2 to forward all traffic bound for n1p3 to go to port 7. We will do this by first deleting all route entries at port 2 and then adding one route entry to forward packets destined for 192.168.1.64 (n1p3) to go to port 7.


• Open the route table at port 2:
  Select Port 2 => Configuration => Route Table
• Hold down the shift key and select (left-clicking) the first entry (192.168.1.16/28) in the routing table.
• Then, hold down the shift key and select (left-clicking) the last entry (192.168.1.128/28).

  These two actions will select all entries between and including the first and last entries.

• Select Route Table => Edit => Delete Route
• In the main RLI window, select File => Commit



The route entries will disappear; the the bandwidth chart will show no traffic; and the ping command will show the "Destination Net Unreachable" message.
Recall that the bandwidth chart is showing the traffic volume enterring the ingress-side of the switch fabric at port 2. Since there are now no entries in the routing table at port 2, all incoming packets will be dropped and not leave the ingress-side of port 2.



• Select Route Table => Add Route
• Edit the route entry so that the prefix/mask field is 192.168.1.64/32 and the next hop field is 7.


• In the main RLI window, select File => Commit

  Traffic will reappear in the bandwidth chart, and the ping command will show traffic has resumed.

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