The present document provides an information model for the unidirectional performance monitoring of Synchronous Digital Hierarchy (SDH) network. This model describes the managed object classes and their properties for the performance monitoring function@ as defined in ITU-T Recommendation G.784 [3] and as related to SDH Network Elements (NEs). These objects are useful to describe information exchanged across interfaces defined in ITU-T Recommendation M.3010 [5] Telecommunications Management Network (TMN) architecture for the management of the performance monitoring function. Synchronous Digital Hierarchy (SDH) performance monitoring functions are used to monitor specified performance events of specified termination points managed objects and to report these performance data@ as well as quality of service alarms to its managing system according to a given schedule. ITU-T Recommendation M.2120 [4] defines maintenance of transport network@ ITU-T Recommendation G.784 [3] defines the management of SDH based NE. The present document defines the object model based on ITU-T Recommendation Q.822 [6] according to the requirements described in ITU-T Recommendation G.784 [3] and ITU-T Recommendation M.2120 [4]. This model uses generic mechanism defined in ITU-T Recommendation Q.822 [6]. The information model for bidirectional performance monitoring is covered by ITU-T Recommendation G.774-01 [1]@ the one for unidirectional performance monitoring by ITU-T Recommendation G.774-06 [2]. The present document reuses functionality of ITU-T Recommendation G.774-01 [1] and G.774-06 [2] wherever possible. The present document defines: - an information model@ as related to the unidirectional performance monitoring function for the SDH. The present document does not define: - the protocol stack to be used for message communication; - the network level management processes; - the application contexts; - the conformance requirements to be met by an implementation of this information model; - information models for other systems or equipment. The information model defined here (and the corresponding message set) is concerned with the management of NEs@ the equipment by which they are implemented and the functions contained within them. More precisely@ it applies to an equipment domain visible at the element manager to element interface and is only concerned with information available within that domain. Information proper to the domain of a network level management process is not included within this model.