Summary

Recommendation ITU-T G.989.3 specifies the transmission convergence layer of 40 Gigabit-capable passive optical network (NG-PON2) systems providing optical access for residential, business, mobile backhaul and other applications.

A NG-PON2 system supports multiple wavelength channels and enables flexibility to add capacity as the demand grows to 100 Gbit/s and beyond. A NG-PON2 system may contain a set of time and wavelength division multiplexing (TWDM) channels, or a set of point-to-point wavelength division multiplexing (PtP WDM) channels, or both. The TWDM channels operate at the nominal line rates of 9.95328 and 2.48832 Gbit/s in both downstream and upstream directions. The PtP WDM channels support nominal line rate classes of 1.25 Gbit/s, 2.5 Gbit/s and 10 Gbit/s, depending on the PtP WDM client.

The transmission convergence (TC) layer is the protocol layer of the NG-PON2 system that is positioned between the physical media dependent (PMD) layer and service clients. It builds on the Recommendation ITU‑T G.987.3, with modifications for NG-PON2 specific features.

This Recommendation forms an integral part of the ITU-T G.989 series of Recommendations (ITU‑T G.989, ITU-T G.989.1 and ITU-T G.989.2) that, together with the ONU management and control interface (OMCI), Recommendation ITU-T G.988, specifies a coherent set of access transmission systems. The NG-PON2 system is also a member of the ITU-T G.9802 family.

Amendment 1 contains necessary additional details and clarifications for the Recommendation and provides regular specification maintenance.

Amendment 2 continues the evolution of NG-PON2 transmission convergence (TC) layer, introducing TWDM channel bonding, making additions and changes to the PLOAM channel, providing DBA enhancements, and performing regular specification maintenance.

This Amendment 3 clarifies the use of SeqNo in the upstream PLOAM messages, clarifies the distinction between Performance Monitoring counters and other Performance Monitoring parameters, and provides regular specification maintenance.