Power broker

By Mark Gibbs
Network World, 02/18/02

We got tired of having to march into the computer room to power cycle various devices when they locked up, and then we remembered a device sitting in our storage room - an NPS-115 network power switch from Western Telematic.

NPS-115 is a 19-inch, rack-mountable power switch with serial (RS-232), modem and 10Base-T network interfaces for remote control. The "115" indicates the voltage input, and there's a 230-volt version, the NPS-230.

The device can control eight power outlets (also referred to as plugs) divided into two groups of four with up to 15 amps per group (that's a maximum of 10 amps per group for NPS-230). Because each group of four ports has its own power cord, you'll need two wall outlets to power all eight ports. In a mission-critical installation you would provide power from an uninterruptible power supply to each group of ports.

On power-up, the outlets are enabled sequentially with a configurable delay for switching on each successive outlet. This lets you provide a delay for, say, a router to power up before a Web server to ensure that no start-up error conditions are generated.

Out of the box, the NPS device provides a 5-second delay (referred to as the boot delay) as each sequential port is being switched on. If you want to change the boot delay, control NPS over an IP connection or selectively power down and power up outlets you'll have to configure the NPS.

DIP switches can control four options: serial interface rate (9.6K or 38.4K bit/sec), default boot delay (5 or 10 seconds), character echo (yes or no) and disconnect timeout - the duration after which NPS automatically logs out the console that applies to whatever interface is used.

To set up NPS you can connect via serial port or dial-up using the modem port (the former is preferable, for obvious security reasons). We used a terminal emulator on a PC (Windows Hyperterminal) via a serial port to the NPS' serial port and a null modem cable (the one that comes with PCsync, which we discussed a few weeks ago).

NPS uses a simple command line interface that lets you set up general, modem and network options. The most important of the general options is the system mode password, which allows control over all aspects of NPS. There are also user mode passwords providing individual control of specific outlets.

Before NPS can be controlled via a telnet interface over IP, the device must be configured using a serial or modem interface. The telnet interface is handy but not safe unless a firewall protects it - there's no encryption on the connection, so access passwords are in plain text.

The telnet interface requires an IP address, subnet mask and gateway address to be defined. You also can define IP security through five layers of filters that let you deny or allow specific IP address ranges. This is good because it lets you limit access to NPS to just your intranet.

The front panel offers a simple LED display indicating when the control interface is ready, when a command is received, when the modem port is active, when a telnet session is in progress and the on or off status of each plug.

We would like to see the telnet interface replaced by a Web server with Secure Sockets Layer so that IP connections would be secure. We plan to front-end our NPS with our intranet Web server so a Web page with a script can drive the NPS.

In system mode you can assign names to individual plugs, which makes remote control much easier. Through the command-line interface you can examine the status of outlets or turn off, turn on, or power cycle (reboot) outlets individually in user mode or individually or collectively in system mode.

NPS is a great device. It is almost foolproof and does exactly what it is supposed to do for the reasonable price of $600. We love it and award it nine gearteeth out of 10.