Y1731

Y.1731, also written as Y1731, is an ITU-T Recommendation that defines operations, administration, and maintenance OAM and performance management for Ethernet-based networks. It provides methods to measure and report service performance metrics such as loss, delay, and jitter, enabling operators to monitor quality of service and diagnose network issues.

Scope and applicability: The specification targets Ethernet access, aggregation, and core networks carrying Ethernet services. It supports end-to-end and segment-level performance monitoring and is designed to work with other Ethernet OAM mechanisms, such as Connectivity Fault Management (CFM), and with service activation testing in Y.1560. It applies to Ethernet interfaces, VLANs, and MPLS-TP deployments.

Performance metrics and measurement: Y.1731 defines key metrics including frame loss, delay, jitter, and availability. It describes active performance measurement procedures, using dedicated measurement frames to collect timing information and loss data, as well as reporting and interpretation rules. It also specifies how measurement data should be organized and exchanged between network elements for SLA validation.

Measurement modes and procedures: The standard supports both one-way and end-to-end two-way measurements, with mechanisms to timestamp frames and compute latency and jitter. It provides guidance on measurement intervals, data reporting, and fault localization to support operational monitoring and service assurance.

Impact and usage: Y.1731 is widely adopted in Ethernet-based service provider networks and in managed enterprise networks to quantify service quality, detect performance degradations, and support SLA guarantees. It interoperates with other OAM and PM standards to provide a comprehensive fault and performance management framework.

History and references: Y.1731 has undergone revisions to accommodate evolving Ethernet technologies and integration with MPLS-TP and other ITU-T PM frameworks. It sits alongside related standards such as ITU-T Y.1560 for service activation testing and PM mechanisms used by network equipment vendors.