Control and Configure Nodes

This page explains user access CMUlab laptops. To learn how to create and swap in an experiment, go to Create Experiments.

Controlling and Configuring Nodes

Once an experiment is successfully swapped in, user will have full access to the laptops that are allocated to this experiment.

Node Types

The CMUlab currently uses Dell D610, D620 and D630 laptops for the emulator project. Each laptop is connected to the Emulator using an Atheros wireless card. We use the MadWifi device driver.

The Emulator provide several additional functions:

multipath channels between several laptops;
several laptops are connectd to USRPs as the wireless interface (connected to the Emulator).

See the current system configuration page (or by going to the CMUlab status page: https://boss.cmcl.cs.cmu.edu/nodecontrol_list.php3) for more details on the capabilities of individual nodes and for information on the current status of each node.

Setting up and Access to Nodes

You can configure the wireless interfaces of the nodes from your CMUlab ns-2 script, as is described in the CMUlab documentation. However, this occasionally fails or you may want to override the settings in the ns-2 script. You can do this by logging into the nodes, as described in this section.

CMUlab automatically sets up password-less ssh on the nodes in your experiment, and users are able to ssh to these nodes from emucontrol-1.ece.cmu.edu or ops.cmcl.cs.cmu.edu directly. For example:

 username@emucontrol-1.ece.cmu.edu> ssh nodew1.<experimentID>.<projectID>.cmcl.cs.cmu.edu

CMUlab does not allow root access on those nodes. Instead, 'sudo' is used to provide access to most critical commands. In the ~/emuNode folder on each node, there are several useful scripts that help to manually start up the wireless interface:

down - Shutdown the wireless interface;
apStart - Start the wireless interface and configure to be an access point;
managedStart - Start the interface in managed mode;
hocStart - Start the interface in ad hoc mode;

Note: apStart, managedStart and hocStart obtain the IP address through the environment variable "WIRELESS_IP". Make sure the value of "WIRELESS_IP" is initilized before running any of these scripts.

In the folder ~/emuNode, there is another stand-alone file: "NodeDaemon". This script is used by the startDaemon on emucontrol-1.ece.cmu.edu. More details will be introduced in Set up and Run simple experiment.

Rebooting a crashing node

You can reboot node directly from CMUlab website ->Node Status -> pcs.