This Recommendation addresses management aspects of optical transport network (OTN) elements containing transport functions of one or more layer networks of the OTN as described in [ITU-T G.709]. The management of optical layer networks is separable from that of its client layer networks; therefore the same means of management can be used regardless of the client. The management functions for fault management@ configuration management@ account management@ performance management and security management are specified. This Recommendation describes the management network organizational model for communication between an element management layer (EML) operations system (OS) and the optical equipment management function within an OTN network element (NE). The architecture described in this Recommendation for the management of OTNs is based upon the following considerations: ?C The management view of NE functional elements should be uniform whether those elements form part of an inter-domain interface (IrDI) or part of an intra-domain interface. Those properties necessary to form such a uniform management view are to be included in this Recommendation. ?C OTN layer network entities (OLNEs) refer to trail termination (TT)@ adaptation and connection functions as described in [ITU-T G.872] for the OTN digital layer. ?C An NE may only contain optical layer network entities. ?C An NE may contain both optical layer network entities (OLNEs) and client layer network entities (CLNEs). ?C CLNEs are managed as part of their own logical domain [e.g.@ synchronous digital hierarchy (SDH) management network]. ?C CLNEs and OLNEs may or may not share a common message communications function (MCF) and management application function (MAF) depending on application. ?C CLNEs and OLNEs may or may not share the same agent.