![]() ![]() When a Severe-Error is reported, the FE (Frame Bit Errors) count is set to 0. Also, 2 of 4, 2 of 5, or 3 of 5 errored framing bit criteria can be used to declare a Severe-Error (SE). This occurs when two or more framing bit errors are detected in any 3 mS window. This occurs when the CRC polynomial calculation performed before transmission does not match the CRC calculation done upon reception. Depending upon the equipment, this can occur when 2 of 4, 2 of 5, or 3 of 5 framing bits are in error. Occurs when the equipment senses errors in the incoming framing pattern. This alarm is a repetitive 16-bit pattern consisting of 8 "marks" (1) followed by 8 "spaces" (0) (11111111 00000000) and is transmitted for at least 1 second.Ī LOS condition occurs when no pulses have been detected in a 175 +/- 75 pulse window. When the equipment enters a Red-Alarm state, it returns a Yellow-Alarm back up the line of the received OOF. This alarm state is cleared when no OOF conditions occur for at least 1 second Occurs when the equipment detects a continuous OOF condition for 2.5 seconds. It is usually an indication of a physical layer problem. This AIS-Alarm consists of an unframed all ones signal sent to maintain transmission continuity. When a data path is broken the first downstream device to detect this LOS/OOF condition sends an AIS-Alarm on down the line (2.5 seconds of an OOF condition will also cause the device to go into Red-Alarm and send a Yellow-Alarm back up the line). The AIS is also known as a "All-Ones", "Blue-Alarm" or "Keep-Alive" signal.
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