Stable optical power is the foundation of every high-capacity optical transport system. Even minor deviations—whether too high, too low, or unstable—can impact signal integrity, trigger service alarms, or interrupt traffic on DWDM, OTN, or long-haul optical line systems. Optical Transport Network (OTN) systems have several alarms to monitor network health and detect issues that could impact performance. Here are the key OTN alarms and their explanations: 1. It is based on wavelength division multi-plexing technology. digital transmis-sion, and optical domain, e. These alarms are raised. ITU-T members can see the details of the reports by accessing ITU-T SG15 temporary documents for the December 2021 meeting as indicated in the reference: https://www.