xxii Issue 1 December 1997
Contents
9 Maintenance Description
â– Overview 9-1
Three-Tiered Operations 9-1
â– Single-Ended Maintenance Philosophy 9-4
Multi-Vendor OI 9-6
â– In-service (IS) Upgrades 9-8
Software Upgrades 9-8
â– DDM-2000 OC-3 and OC-12 Software Compatibility 9-9
â– Maintenance Signaling 9-10
â– Fault Detection, Isolation, and Reporting 9-16
Detection 9-16
Isolation 9-16
Reporting 9-16
â– Protection Switching 9-17
Automatic Line Protection 9-17
Status of ACTIVE LED on OLIUs 9-17
APS Initiation Criteria 9-18
Equipment Protection 9-20
Synchronization Reference Protection 9-20
Path Protection Switching (Path Switched Rings) 9-21
Path Protection Scheme 9-22
Dual Ring Interworking (DRI) Path Protection
Scheme 9-24
OC-3/OC-12 Path Switched Ring (0x1) 9-26
Status of ACTIVE LED on Rings 9-26
â– Loopbacks 9-26
â– Tests 9-27
Transmission Tests 9-27
Operations Interface Tests 9-27
â– Performance Monitoring (PM) 9-27
DS3 Performance Monitoring (PM) 9-29
DS3 Path PM 9-29
P-Bit 9-29