Objective
Conntech 2000-ESC
Testing a DWDM installation
Compliance
ConnTech2000 Physical Layer Interface
Summary

This application note has been written as a result of inquiries from telecommunication carriers and communication support groups responsible for transporting ESCONÔ data over DWDM equipment. These service providers have been kindly informed by their customers they do not wish to be a test case when their ESCONÔ data is to be transported over metropolitan DWDM networks. This application note describes the process of testing DWDM installations and explains how the Conntech 2000–ESC is ideally suited for this application.

The ConnTech 2000–ESC is a test and analysis tool developed by Connecticut Technology Products supporting the ESCONÔ S channel protocol. The ConnTech 2000–ESC is both an ESCONÔ Analyzer and an ESCONÔ Test Generator. This discussion will focus on the ESCONÔ Test Generator portion of the ConnTech 2000–ESC. The ConnTech 2000–ESC Test Generator is driven by a common internal transmitter running at a rate of 200Mbs using ESCONÔ protocol. Two independent receiver ports allow the monitoring of the ESCONÔ links under test. The status of the two links is continuously displayed by the Windows application within an Event Log field. The status reporting includes Code Violation detected, CRC error detected, Start of Frame/End of Frame Delimiter error detected, Loss of Light detected, and Loss of Data detected. All errors/status detected are time and date stamped within the Event Log by the Windows application. The Event Log may be saved as a text file to provide the user and or customer a final record of the link testing results. A Test Information field is provided to allow the user the means to enter the specifics of the testing. ESCONÔ Ordered Sequences can be generated and the response captured by the test generator. The ConnTech 2000–ESC also has a Bit Error Rate Generator/Receiver used during link testing. Standard PRBS patterns and up to four byte user-defined data patterns are supported.

Once the DWDM equipment has been installed and it’s POST test has been completed two events normally follow.

First, the equipment is connected and the end to end configuration is verified as correct.

Second, using the DWDM equipment, the link is tested end to end for proper power levels at the received end. It’s important here that 8B/10B encoding be used as the source to ensure the same "1" / "0" pattern and power density distribution used is the same as the ESCONÔ data frame. Power level measurements taken under these conditions will provide valid power level readings for the link.[1]

The ConnTech 2000-ESC generates 8B/10B encoded ESCONÔ frames with start of frame, end of frame and CRC delimiters. Idle patterns are generated automatically and inserted in between valid frames to create a real time ESCONÔ environment while these measurements are being made. If desired any of the five ESCONÔ Ordered Sequences can be generated and used as the pattern for the optical power measurement. User selectable test patterns provided within the ConnTech 2000 are readily available for use (point and click) by the test operator. Test patterns are automatically placed within the ESCONÔ frame delimiters.

Once power levels measurements have been made and are within the acceptable limits, a BERT test should be run over the same circuits for a minimum of 24 hours using a stressful PRBS pattern. Our experience in this testing has shown in many cases that the 2¹⁵-1 or 2²³-1 PRBS patterns have a tendency to stress PLL‘s within receiver modules. If there is a weak link in the system you want to know about it now rather than after it has been turned over to the customer.

As the test is being set up with the far end in a loop back configuration, it is useful to be able to insert one error into the system to verify the equipment and cabling are configured as planned. Inserting a single error is accomplished from the BERT Test Window. With confirmation that an error was sent and detected you are ready to start the 24-hour test cycle. Using the ConnTech 2000-ESC, select the data rate typically 19.6 Mbytes, frame size typically 1K, select the PRBS pattern typically 2²³-1 , enter test information model #, serial #, Customer’s name, location, etc. Clear the error counter and select the Test Control button, which starts the test. The test is now running!

The ConnTech2000-ESC meets or exceeds the IBM ESCONÔ optical physical layer specifications as defined in the IBM Enterprise Systems Architecture/390, ESCONÔ I/O Interface, Physical Layer Document

SA23-0394-00. Also the ConnTech2000-ESC generates ESCONÔ Data Frames and ESCONÔ Ordered Sequences that comply with the Link Level Transmission and Reception of Characters as defined in the IBM Enterprise Systems Architecture/390, ESCONÔ I/O Interface Document, SA22-7202.

ESCONÔ Multimode Transmit Interface Specification:

Optical Output Power = Min -21dBm, Typical -17.7dBm, Max -14.5dBm

Rise Time = Typical 1.2ns, Max 1.7ns

Fall Time = Typical 1.2ns, Max 1.7ns

Center Wavelength = Min 1285nm, Typical 1325nm, Max 1355nm

Data Rate = 200Mb Typical to 220Mb Max

Optical Output Power = Min -19.5dBm, Typical -16.0dBm, Max -14.0dBm

Rise Time = Min 0.6ns, Max 1.7ns

Fall Time = Min 0.6ns, Max 1.7ns

Center Wavelength = Min 1285nm, Typical 1320nm, Max 1355nm

ESCONÔ Multimode Receiver Interface Specification:

Optical Saturation Level = Max -14.5dBm

Optical Sensitivity = Min -31dBm, Max -14.5dBm

Data Rate = Min 10Mb, Max 200Mb

Optical Saturation Level = Max -14.0dBm

Optical Sensitivity = Min -32dBm, Max -14.0dBm

Optical Wavelength = Min 1270nm, Max 1380nm

Why is the ConnTech 2000-ESC being used in metropolitan areas to support ESCONÔ environments?

1. Carriers and communications support groups have been kindly informed by their customers that they do not want their ESCONÔ data to be the test case when ESCONÔ transport is required and DWDM equipment will be used within the communications circuit. Recent customers include brokerage houses in metropolitan areas and large network carriers.
2. The communication support groups and carriers want to eliminate the issue of "finger pointing" when the communications circuits are not functional or are experiencing intermittent errors. Validating the transmission equipment with a 24 hour test using data that is identical to the ESCONÔ rates and format removes doubt that the transmission system is the error generating candidate.
3. The customer wants a guarantee that the communications circuits have been tested using ESCONÔ protocol at the 200Mbs rate. The circuit should be tested for an error free environment for 24 to 48 hours before placing the customer's ESCONÔ data onto the circuit.
4. Customers would like to have a record that a test has been performed which shows the equipment being used, the start and end times, plus any record of errors logged during the test period.
5. Selected tests with the ConnTech 2000-ESC can provide very stressful test patterns within the ESCONÔ data frame. Specific PRBS patterns have identified problems at repeaters when other test equipment has determined that the end to end communication circuits is functioning properly.

For a copy of the Conntech 2000-ESC data sheets and manual please visit our downloads page.

For pricing and availability go here to locate a sales representative in your area or contact Connecticut Technology Products, LLC at mktg@c2p.com .

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