Alcatel-Lucent 1850 TSS-5 provides maintenance signaling compliant with the SONET standard (ANSI T1.105) and GR-253-CORE. When Alcatel-Lucent 1850 TSS-5 detects failure conditions on transmission signals, maintenance signals are inserted into the transmission signals in the upstream or downstream direction to notify other network elements.
Alcatel-Lucent 1850 TSS-5 supports the following SONET/SDH maintenance signals:
Alarm indication signals (AIS) notify downstream equipment that a failure has been detected and alarmed by some upstream equipment. Alcatel-Lucent 1850 TSS-5 generates the following alarm indication signals:
SONET Line AIS (AIS-L): Line AIS is generated when an incoming loss of signal (LOS) or loss of frame (LOF) is detected on the incoming OCN signal.
SDH Multiplex Section AIS (MS-AIS): Multiplex Section AIS is generated when an incoming loss of signal (LOS) or loss of frame (LOF) is detected on the incoming STMN signal.
SONET STS Path AIS (AIS-P): STS path AIS is generated when an incoming loss of signal (LOS), loss of frame (LOF), line AIS (AIS-L), or path loss of pointer (LOP-P) is detected.
SONET VT Path AIS (AIS-V): VT path AIS is generated when an incoming loss of signal (LOS), loss of frame (LOF), line AIS (AIS-L), path loss of pointer (LOP-P), STS path AIS (AIS-P), STS path unequipped (UNEQ-P), or VT loss of pointer (LOP-V) is detected.
SDH VC-N Administrative Unit AIS (AU-AIS): AU-AIS is generated when an incoming loss of signal (LOS), loss of frame (LOF), line AIS (AIS), or administrative unit loss of pointer (AU-LOP) is detected.
SDH VC-N Tributary Unit AIS (TU-AIS): TU-AIS is generated when an incoming loss of signal (LOS), loss of frame (LOF), line AIS (AIS), or tributary unit loss of pointer (TU-LOP) is detected.
When downstream terminating equipment detects a defect (see below for explanation of the defects), the terminating equipment sends a remote defect indication (RDI) upstream to the node that originated the signal. After receiving an RDI that persists for two seconds (±0.5), the originating node (upstream node), generates a remote failure indicator (RFI) alarm. Alcatel-Lucent 1850 TSS-5 generates the following remote defect indication signals:
For SONET Lines, loss of signal (LOS), loss of frame (LOF), and alarm indication signal (AIS-L) are the defects that cause the line terminating equipment (LTE) to send an RDI-L back upstream to the originating LTE which then declares an inc. OCN RFI-L on the line.
For SDH Multiplex Sections, loss of signal (LOS), loss of frame (LOF), and alarm indication signal (MS-AIS) are the defects that cause the line terminating equipment (LTE) to send an MS-RDI back upstream to the originating LTE which then declares an inc. STMN MS-RFI on the line.
For SONET STS Paths, loss of pointer (LOP-P), unequipped (UNEQ-P), and alarm indication signal (AIS-P) are the defects that cause the path terminating equipment (PTE) to send an RDI-P back upstream to the originating PTE which then declares an inc. STSN RFI-P on the STS path.
For SONET VT Paths, loss of pointer (LOP-V), unequipped path (UNEQ-V), and alarm indication signal (AIS-V) are the defects that cause the path terminating equipment (PTE) to send an RDI-V back upstream to the originating PTE which then declares an inc. VT RFI-V on the VT path.
For SDH Low-Order VC-12 and VC-3 Paths, tributary unit loss of pointer (TU-LOP), low-order path unequipped (LP-UNEQ), and tribuary unit alarm indication signal (TU-AIS) are the defects that cause the path terminating equipment (PTE) to send an LP-RDI back upstream to the originating PTE which then declares an inc. VCN LP-RFI on the STS path.
For SDH High-Order VC-4 and VC-44C Paths, administrative unit loss of pointer (AU-LOP), high-order path unequipped path (HP-UNEQ), and administrative unit alarm indication signal (AU-AIS) are the defects that cause the path terminating equipment (PTE) to send an HP-RDI back upstream to the originating PTE which then declares an inc. VCN HP-RFI on the VT path.
Important!
RFI-related alarms are not reported at non-path terminating points because they are not actionable and because the impacted service is not terminated at that node.
Alcatel-Lucent 1850 TSS-5 supports STS-N, VT1.5, and VC-N path unequipped signals. Path unequipped signals are transmitted to notify downstream equipment that the path is incomplete (for example, the absence of a valid cross-connection).
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