The DS1 Facility Link Performance Measurements Summary and the DS1 Facility Link Performance Measurements Detailed Log reports provide the performance measurements for the facilities associated with a DS1 Converter board.

The DS1 facilities provide error bursts instead of single bit errors. Therefore, the operational characteristics of DS1 facilities are more accurately described by the errored seconds, the bursty errored seconds, the severely errored seconds, and the failed seconds.

The DS1 facility performance is based on the number of error events that occur per second. The following are the types of error events:

• Misframe: An erroneous bit pattern in a frame.

• Slip: The deletion or repetition of a frame. This event occurs because of improper synchronization.

• Extended Superframe Format (ESF) 6-bit Cyclic Redundancy Check (CRC-6): A data communication error over the DS1 link using the ESF format. This event occurs because of a mismatch between the calculated CRC-6 character appended to the transmitted data and the CRC-6 character recalculated by the receiver.

The DS1 facility performance is measured using the following data:

• Errored second: A second that contains one or more error events.

  The percentage of Error Free Seconds (%EFS) is calculated as:

  

• Bursty errored second: A second that contains 2 to 319 error events.

• Severely errored second: A second that contains 320 or more error events.

• Failed second: An event of 10 or more consecutive severely errored seconds. A failed second event is cleared when no severely errored seconds are detected for a period of 10 seconds.

• Controlled slip second: A second with one or more controlled slips.

• Loss of Frame count: The number of times a loss of frame is detected. The loss of frame is a continuous loss of signal or an out-of-frame condition for more than 2.5 seconds.

If the misframe or slip errors become severe, an alarm is raised. The rate at which the errors occur determines whether the alarm is minor or major. The maintenance for Communication Manager identifies the procedures that the maintenance personnel must perform to resolve the alarms.

The error event data is available for up to 24 hours in 15-minute increments. The measurement data older than 24 hours is overwritten by the current measurement data.

A system reboot from the tape clears the error event counters. To clear the DS1 error event counters, use the clear measurements ds1-facility log | esf-error-events | loopback/spantest MedMob command, where Med is the media gateway number, Car is the carrier number, and Mod is the module number.

If a DS1 Converter media module is removed or taken out of service, the measurement data is unavailable for the time that the media module is removed.