Table of Contents
Issue 1 December 1997 9-i
9
Maintenance Description
Overview 9-1
â– Three-Tiered Operations 9-1
Single-Ended Maintenance Philosophy 9-4
â– Multi-Vendor OI 9-6
In-service (IS) Upgrades 9-8
â– Software Upgrades 9-8
DDM-2000 OC-3 and OC-12 Software Compatibility 9-9
Maintenance Signaling 9-10
Fault Detection, Isolation, and Reporting 9-16
â– Detection 9-16
â– Isolation 9-16
â– Reporting 9-16
Protection Switching 9-17
â– Automatic Line Protection 9-17
Status of ACTIVE LED on OLIUs 9-17
APS Initiation Criteria 9-18
â– Equipment Protection 9-20
â– Synchronization Reference Protection 9-20
â– Path Protection Switching (Path Switched Rings) 9-21
Path Protection Scheme 9-22
Dual Ring Interworking (DRI) Path Protection Scheme 9-24
â– OC-3/OC-12 Path Switched Ring (0x1) 9-26
Status of ACTIVE LED on Rings 9-26