message Example: Structure: TL1 autonomous message Example: Structure: TL1 Surveillance and Maintenance Messages TL1 also has application messages for NE and transport surveillance functions. The messages and functions cover a wide variety of NE types, user needs, and supplier innovations. Telcordia GR-833, TL1 Surveillance and Maintenance Messages contains the generic functions and messages that pertain to the following generic types of NEs: Digital Loop Carrier (DLC) Central Office Terminal (COT) Integrated Digital Loop Carrier (IDLC) Remote Digital Terminal (RDT). Digital Terminal and Cross-Connect Equipment Automated Digital Terminal System (ADTS) Digital Cross-Connect System (DCS) Hybrid Add/Drop Multiplexer/Digital Cross-Connect System (ADM/DCS) Optical Add/Drop Multiplexer (OADM) Reconfigurable Optical Add/Drop Multiplexer (ROADM) Low Bit-Rate Voice (LBRV) Terminal. Digital Multiplexing and Line Terminating Equipment Multiplexer (MUX) Add/Drop Multiplexer (ADM) Line Terminating Equipment (LTE) Repeater (REP) Automatic Protection Switching (APS) Equipment. Digital Switching Systems Circuit Switching (CS) System Packet Switching (PS) System (including Access Concentrators). ISDN Switching Systems SONET Transport Systems FITL Transport Systems Passive Optical Network (PON). Metro Ethernet Systems Common Channel Signaling (CCS) Systems Signal Transfer Point (STP) Service Control Point (SCP) Service Switching Point (SSP). Supervisory Systems (SSs) Environment Monitors (EMs) Timing Signal Generator (TSG) An NE address consists of two types of parameters, routing and access. The maintenance functions can be grouped into the following six categories: Alarm Surveillance (AS) − Messages of events or conditions (e.g., carrier group alarms, threshold violations). Performance Monitoring (PM) − Generated performance data (e.g., number of errored seconds, number of slips). Failure Identification (FI) − Mechanisms within the NE to detect and isolate equipment and facility troubles. Recovery and Control (RC) − Maintenance purposes. This includes Maintenance State Control, Loopbacks, External Device Control, Initialization, Emergency Reconfiguration, and Process Inhibit and Termination. Maintenance Measurement (MM) − to be used for overall assessment of the NE maintenance process. Memory Backup (MB) − To/from non-volatile memory within the NE. GR-833 provides detailed descriptions of commands and responses in the TL1 format. External links TL1 Toolkit, an Open Source Perl module for TL1 Telcordia GR-831-CORE - OTGR Section 12.1: Operations Application Messages - Language for Operations Application Messages Network management