HT Communications' Looker takes the guesswork out of bringing up new sites on your frame relay network. Simply plug this device into the digital data service (DDS) jack, and it examines the circuit for common Physical Layer problems and detects frame relay service configurations. Within five minutes, you'll know if you can proceed with your installation, or if you'll need to call your service provider. If you do need help from a telco, you'll know which one to call and what problem the provider needs to fix, thanks to Looker.

I tested a beta version of Looker at the MCI Developers' Lab and was impressed. The product is limited to circuits with data rates under 64 Kbps. (HT Communications says it is testing a T1 version, which is expected to s hip this fall.) Because most frame relay circuits use low-speed access lines, the 64-Kbps vers ion is useful in many installations. Looker is an exceptional value and an essential part of the WAN manager's arsenal.

Easy on the Eyes Looker is a simple, handheld box weighing a little more than a pound, with an RJ-45 jack for the DDS line. A four-line LCD panel provides a readout with three buttons for scrolling and adjusting contrast. An RS-561 jack on the side supports a serial link to a monitor or printer. The aluminum case is reasonably hardened, and it's coated with a scratch-resistant Lexan-Urethane composite that helps the unit stay put.

The unit I tested used an external AC power adapter, though HT Communications says it expects to have testers that operate on "C" batteries by press time. Six alkaline C cells provide 30 hours of normal use.

Looker's real beauty lies in its simplicity. It's the perfect way to check out a circuit before you send in an installation team. A complete test can be perfo rmed by anyone capable of plugging in a telephone. You don't need a manual to work with Looker. In fact, the three sentences that are written on the unit might just be too much documentation! You can also connect the unit to a PC serial port or printer if you want to watch remotely or produce a hard copy report.

In the lab, I examined a variety of frame relay service conditions, and Looker passed nearly every test. First, I plugged it into a dead circuit and, as expected, the unit reported a No Signal status. Next, I installed it on a live 56-Kbps DDS circuit that was not connected to a frame relay switch. Looker then reported a signal present with a data rate of 56,000 bps, and the frame relay test correctly failed with a Not Ready condition.

Finally, I plugged into a live frame relay connection over a 56-Kbps DDS circuit, on which I had configured four Data Link Connection Identifiers (DLCIs)--addresses that identify frame relay permanen t virtual circuit (PVC) end points. Three of these DLCIs were active, while one was set in an inactive state. Looker correctly detected the frame relay local management interface type (T1.617 Annex D). It identified the number of DLCIs available on the link, as well as whether they were active or inactive.

Bug Fixes As is expected with beta releases, this unit had a few minor problems. During testing, one of the DLCI numbers was misreported because of a simple hex-to-decimal conversion error. The unit also reported a high number of bad frames, which turned out to include healthy data frames that were simply not understood by the unit. The released version will provide separate counters for bad frames due to invalid frame or Frame Check Sequence errors and management and data frames.

But this device is so handy, I'd use it even if HT Communications left these things untouched.

Looker focuses on the main indicators of Physical and Data Link Layer status. It reports the most important Physical Layer conditions--including no signal, line rate, bipol ar violations, errored seconds and three types of loopbacks. It detects frame relay link management interface type--LMI, T1.617 Annex D and ITU-T X.36--as well as DLCI numbers and their status--active, inactive, new or deleted.

Of course, Looker doesn't replace your expensive WAN analyzer. Circuits must be taken offline to be tested, and Looker reports only the basic characteristics listed above. Additionally, it doesn't monitor all of the line error conditions commonly found in CSU/DSUs, such as out-of-frame conditions, yellow alarms or severely errored seconds, but it will determine if you are even ready to install the CSU/DSU.

David Willis can be reached at dwillis@nwc.com.