ITU-T G.8021 PDF

This Recommendation covers the functional requirements of Ethernet functionality within Ethernet transport equipment.

This Recommendation uses the specification methodology defined in [ITU-T G.806] in general for transport network equipment and is based on the architecture of Ethernet layer networks defined in [ITU-T G.8010], the interfaces for Ethernet transport networks defined in [ITU-T G.8012], and in support of services defined in [ITU-T G.8011]. It also provides processes for Ethernet OAM based on [ITU-T G.8013]. The description is generic and no particular physical partitioning of functions is implied. The input/output information flows associated with the functional blocks serve for defining the functions of the blocks and are considered to be conceptual, not physical.

The functionality defined in this Recommendation can be applied at user-to-network interfaces (UNIs) and network-to-network interfaces (NNIs) of the Ethernet transport network.

Not every functional block defined in this Recommendation is required for every application. Different subsets of functional blocks from this Recommendation and others (e.g., [ITU-T G.798] and [ITU-T G.806]) may be assembled in different ways according to the combination rules given in these Recommendations (e.g., [ITU-T G.806]) to provide a variety of different capabilities. Network operators and equipment suppliers may choose which functions to implement for each application.

The internal structure of the implementation of this functionality (equipment design) need not be identical to the structure of the functional model, as long as all the details of the externally observable behaviour comply with the equipment functional specification.

Equipment developed prior to the production of this Recommendation may not comply with all the details in this Recommendation.

The equipment requirements described in this Recommendation are generic and no particular physical partitioning of functions is implied. The input/output information flows associated with the functional blocks define the functions of the blocks and are considered to be conceptual, not physical.

Figure 1-1 presents a summary illustration of the set of atomic functions associated with the Ethernet signal transport. These atomic functions may be combined in various ways to support a variety of Ethernet services, some of which are illustrated in Appendix I. In order to reduce the complexity of the figures, the functions for the processing of management communication channels (e.g., OTN COMMS) are not shown. For COMMS functions, refer to the specific layer network descriptions.