Unit installation

FCD-E1 Monitoring Performance 6-1
Chapter 6
Troubleshooting and
Diagnostics
6.1 Monitoring Performance
The performance evaluation and monitoring functions provided by the FCD-E1 for
the main and sublinks are an important tool for testing and troubleshooting
communication links.
This section describes the performance evaluation and monitoring functions.
The functions actually available depend on the use of the CRC-4 function on the
corresponding link:
• CRC-4 Enabled: when the CRC-4 function enabled is used, it is possible to
monitor end-to-end the data transmission performance.
The error detection information is derived from the data payload, by
performing a cyclic redundancy check (CRC). The resulting CRC checksum is
transmitted in addition to the raw data bits.
The receiving end recalculates the checksum and compares the results with the
received checksum: any difference between the two checksums indicates that
one or more bit errors are contained in the current data block being evaluated.
• CRC-4 Disabled: in this case, the FCD-E1 does not support the capabilities
listed above. However, the FCD-E1 is capable of providing statistics of the
bipolar violations.
Performance monitoring parameters are shown in Table 6-1. The parameters
marked with an asterisk (*) indicate performance monitoring with the CRC-4
option enabled.
Displaying the Performance Data on the Front Panel LCD

To display the performance diagnostics data:
1. Bring the cursor to the left-hand field of the top row (if not already there).
2. Scroll to display DIAGNOSTICS in the top row; the right-hand field of the top
row shows ML, meaning that the displayed diagnostics data pertains to the
main link. The second row shows the first performance item for the main link,
and its current value. The displayed item depends on the link type and framing
mode.
3. Bring the cursor to the left-hand field of the second row.
4. Scroll to see the other performance statistics.