Alarms

This chapter provides information about alarms supported for SONET and SDH, and their maintenance.

Alarms are triggered when a component fails or does not perform as expected. Alarms are triggered by the chassis.

Alarms can be defined using the following two terms:

  • Alarm State—It is the state the chassis enters when a certain event occurs. For example, the state of the chassis when the ambient temperature is beyond the specified limits.

  • Alarm Indication—It is a visual signal to indicate the alarm state. For example, the TEMP LED glows red if the ambient temperature is beyond the specified limits, and it turns green if the ambient temperature is within specified limits.

    Typically, a failure condition detected by a chassis results in one or more error conditions sent both upstream and downstream on the network.

    • Alarm Indication Signal (AIS)—AIS alarms are reported downstream from a detecting device, and to prevent consequential downstream failures or alarms from being raised.

    • Remote Defect Indicator (RDI)—RDI alarms are always reported upstream from the detecting device.


Note


Even when the controller is in the down state with alarms, the cross connection between the controllers is up.


Restrictions for Alarms

  • In T3, an AIS alarm is supported only in the framed mode and not supported in the unframed mode.

SONET Alarms

SDH Alarm

The following table lists the types and sub types of SDH Alarms.

Table 1. SDH Supported Alarms

Alarm Type

Sub Alarm Type

Section Alarms

  • LOS — Loss of Signal

  • LOF — Loss of Frame

  • RS-BIP — Bit Interleaved Parity

Line Alarms

  • MS-BIP — Multiplex Section-Bit Interleaved Parity

  • MS-REI — Multiplex Section-Remote Error Indication

  • MS-AIS — Multiplex Section-Alarm Indication Signal

  • MS-RDI — Multiplex Section-Remote Defect Indication

  • AU-AIS — Administrative Unit-Alarm Indication Signal

  • AU-LOP — Administrative Unit-Loss of Pointer

STS Path Alarms

  • HP-UNEQ — High order Path-Unequipped

  • HP-PLM — High order Path-Payload Label Mismatch

  • HP-RDI — High order Path-Remote Defect Indication

  • HP-BIP — High order Path-Bit Interleaved Parity

  • HP-REI — High order Path-Remote Error Indication

  • TU-LOM — Tributary Unit-Loss of Multiframe

  • TU-AIS — Tributary Unit-Alarm Indication Signal

  • TU-LOP — Tributary Unit-Loss of Pointer

VT Path Alarms

  • LP-UNEQ — Low order Path-Unequipped

  • LP-PLM — Low order Path-Payload Label Mismatch

  • LP-RDI — Low order Path-Remote Defect Indication

  • LP-RFI — Low order Path-Remote Failure Indication

  • LP-BIP — Low order Path-Bit Interleaved Parity

  • LP-REI — Low order Path-Remote Error Indication


Note


TIM alarms are not supported.