This feature allows the user to track CRC (cyclic redundancy check) errors received on a specific port. The detection mechanism is based around a configurable threshold specified by the administrator. Two thresholds are configurable, one for CRC degrade and one for CRC signal fail. The first threshold crossing generates an alarm, log entry, and trap, but does not bring the physical port down, while the second (signal fail) threshold crossing logs an alarm, generates a trap, and brings the port operationally down.
The thresholds are configurable with the CLI command config>port>ethernet crc-monitor.
This behavior is enabled on a per-port basis. By default, the command and functionality is disabled for signal degrade and signal fail.
The user can configure different values for the sf-threshold and the sd-threshold. However, the sf-threshold value must be less than or equal to the sd-threshold value.
The values provided by the user for threshold and multiplier are used to compute the error ratio as (multiplier * (10 ^ - (threshold value)). Port statistics are collected once per second and accumulated over the configured window size. Each second, the oldest sample is discarded and the new sample is added to a running total. If the error ratio exceeds the configured threshold (as computed previously) over the window size for 2 consecutive seconds, appropriate actions are taken as follows.
If the number of CRC errors exceeds the signal degrade threshold value, a log warning message, syslog event and SNMP trap with the message ‟CRC errors in excess of the configured degrade threshold <M>*10e-<N> Set” is raised.
If the CRC error rate increases further and exceeds the configured signal fail threshold value, an alarm log message, syslog event, and SNMP trap are raised, and the port is brought operationally down.
When the condition is cleared, a SNMP trap message to clear the event is generated.