Table of Contents
Issue 1
December 1997
9-i
9
Maintenance Description
Overview
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Three-Tiered Operations
Single-Ended Maintenance Philosophy
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Multi-Vendor OI
In-service (IS) Upgrades
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Software Upgrades
DDM-2000 OC-3 and OC-12 Software Compatibility
Maintenance Signaling
Fault Detection, Isolation, and Reporting
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Detection
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Isolation
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Reporting
Protection Switching
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Automatic Line Protection
Status of ACTIVE LED on OLIUs
APS Initiation Criteria
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Equipment Protection
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Synchronization Reference Protection
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Path Protection Switching (Path Switched Rings)
Path Protection Scheme
Dual Ring Interworking (DRI) Path Protection Scheme
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OC-3/OC-12 Path Switched Ring (0x1)
Status of ACTIVE LED on Rings