With the rising popularity of ISDN, as well as its widespread use
internationally, we see new ISDN products all the time. But how to evaluate all these new
products? It can be a challenge, especially considering the complexity of the various
ordering codes for ISDN, not to mention all the various protocols. This is where an ISDN
simulator can come in handy. It can let you concentrate on the product youre
studying, not the usual complications that crop up whenever you work with ISDN. Another
benefit from using an ISDN simulator is that it saves you money, particularly if
youre in an area where you must pay for ISDN service by the minute.
The ISDN simulator we evaluated was Merge Technologys ISDN 2000AF
FLASH Memory Emulator, a device with multiple-protocol emulation. The FLASH
refers to the 2000AFs Flash memory, which allows you to download upgrades and
enhanced protocol libraries.
An added convenience is the 2000AFs software, Protocol Analyzer.
This software allows you to observe, save, and print trace information; adjust filter
settings; and modify the settings of the 2000AF. You can configure the 2000AF for
stand-alone operation or computer-controlled operation. This capability of the ISDN 2000AF
allows you to use it as a mobile demonstration tool or as a dedicated bench-top
development and diagnostic tool.
SPECIFICATIONS
Total Ports (Lines)
Two ISDN Basic Rate Interface (2B + D) lines for end-to-end emulation.
Interfaces At Each Port
U (2B1Q) and S/T (ASI bipolar) interfaces at each line.
Connectors
4 each RJ-45.
Maximum Devices
6 (4TE + 2NT).
U Indicators
Frame Sync, Near End Bit Error, Far End Bit Error, Local Activation, NT-1 Activation,
Power, Embedded Operation Channel.
S/T Indicators
Receive INFO State, Transmit INFO State, Q Bits, S Bits.
Other
- Speech, 3.1 KHz Audio, 7 KHz audio, Circuit Mode Data, and D Channel Packet Code Data.
- Point-to-point and point-tomultipoint configurations.
- In-band tones and primary line power to six terminating devices.
INSTALLATION/DOCUMENTATION
Installation was simple. We removed the packaging, connected the handheld portable device
to the main unit, and then connected ISDN product(s) to the port(s) on the unit. To avail
ourselves of the 2000AFs advanced functions, we installed the Protocol Analyzer, a
Windows program that shipped with the 2000AF. Installing this software program was very
easy it was just one diskette.
The documentation was very good. It described how to access features with step-by-step
instructions, and it contained many screenshots of the software displays. In addition, the
manual explained some of the basics of ISDN.
FEATURES
- Simulates National ISDN-1, AT&T Custom, DMS-100, and ETSI signaling protocols.
- Supports auto-initializing terminals (SPIDs), including AT&T custom.
Captures and displays or prints packet headers, call control messages, and information
elements.
- Monitors physical layer status and control parameters.
- Monitors and traces data link layer protocol operations.
- Isolates and fine-tunes packet operations like automatic TEI assignment, multiple frame
establishment, and receiver ready/not ready conditions.
- Monitors and traces network layer call control functions.
- Confirms every detail of ondemand, circuit-switched call control procedures by observing
messages and information elements.
- Tests and demonstrates features unique to your product using switchspecific messages.
OPERATIONAL TESTING
We tested the ISDN simulator using a pair of U.S. Robotics ISDN modems. We connected to a
Windows NT 4.0 machine running Microsoft Internet Information Server and were able to
download Web pages at lightning speed. We also hooked up a pair of ISDN phones and were
able to call from one phone to the other with no problem. We found that voice and Circuit
Mode Data (CMD) connections were supported on either B Channel, while the D Channel Packet
Handling Function (PHF) simulated X.25 Packet Mode Data (PMD) calls.
SPIDs/Protocols
One nice feature of the 2000AF is that it comes with predefined Service Profile
IDs (SPID). The predefined SPIDs auto-initialize Directory Numbers and assign Service
Profiles that permit multiple call appearances, caller-ID, unlimited call types, and other
services.
The FLASH memory capability of the ISDN 2000AF allowed us to easily enter custom
Service Profile Identification (SPID) numbers or download new protocols. On the network
layer, this unit supports National ISDN-1, AT&T 5ESS Custom, Northern Telecom DMS-100,
and European Telecommunications Standards Institute (ETSI) call control, including
codesets 0, 5, 6, and 7, and NETwork ESCape message types.
Display Screen/Printer
We liked the 2000AFs display screen, which reported the different status
conditions. For example, it indicated when the unit was being restarted. It also displayed
the ISDN phone numbers for the two ports. The 2000AF also has a printer option. If you
take advantage of this option, you can more easily test, debug, and monitor various
conditions.
Handheld Device
We used the handheld device to change various parameters on the ISDN simulator.
It hooks right into the serial port of the 2000AF, and we were able to quickly and easily
modify various settings. The hand-held device has arrow keys which allowed us to scroll
through the screen until we found the option we wanted to select. Its only about a
3-inch wide display, but we were impressed with the ability to scroll through the various
menu screens to look at or modify settings.
Protocol Analyzer
The 2000AF comes with software called Protocol Analyzer for Windows, or PAW for
short. Setting up the software was pretty straightforward. We were able to change the ISDN
switch type from a simple drop-down box. The PAW software, a very powerful and useful
utility for tracking and monitoring, lets you set up trace and filters. Software-based LED
lights change color as data passes through the simulator, making it easy to monitor
various conditions. Both the U and S/T interfaces can be monitored from this screen .
CONCLUSION
With the 2000AF, you can emulate end-to-end, real-time ISDN-BRI calls. In addition, you
can perform complete call handling without a PC, without a switch or PBX, and without ISDN
lines. By obviating the use of live ISDN lines, the 2000AF saves money. It
also saves time, by taking the variables associated with real ISDN telephone lines out of
the loop.
This product is a perfect tool for trade shows or other mobile demonstrations. It can
also facilitate the development and testing of ISDN products. We particularly liked the
products handheld device, which gives you everything you need to set up and control
the 2000AF. With this handheld device, you neednt lug a computer to wherever you
need to demonstrate an ISDN product. |