Summary

Recommendation ITU‑T G.994.1 provides a flexible mechanism for digital subscriber line (DSL) transceivers to exchange capabilities and to select a common mode of operation. It includes parameters relating to service and application requirements as well as parameters pertinent to various DSL transceivers. This Recommendation is currently an integral part of the start-up procedure for Recommendations ITU‑T G.991.2, ITU-T G.992.1, ITU-T G.992.2, ITU-T G.992.3, ITU-T G.992.4, ITU-T G.992.5, ITU-T G.993.1, ITU-T G.993.2, ITU-T G.993.5, ITU-T G.9701 and ITU-T G.9711. It is anticipated that future DSL Recommendations will also be able to make use of this Recommendation. Provisions are also included for exchanging non-standard information.The 2021 version of this Recommendation fully integrates the Amendment 1 to Recommendation ITU-T G.994.1 (2018) and includes the following new technical material:

- A new annex with a collision control protocol for point-to-multipoint operation

- Modify the mandatory carrier set for G.9701 Annex X with operation over coax

- A new annex M with managed objects in a new format compatible with a YANG model

- Add codepoints for the support of G.9711