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Evaluating Tributary Jitter from the SDH Network Application Note 1258 2 Introduction The network architecture The impact of this pointer activity will be to increase the jitter on the The innovation of using pointers In the long term, the synchronous asynchronous tributary signal to track the position of the Virtual SDH network may develop to passing out of the SDH island. Container (VC) within SDH the state where asynchronous This will produce an accumulation signals has produced many networks will only exist at the of jitter on the tributary signal as benefits that will minimize the periphery of the synchronous it traverses the multiple islands in cost and complexity of network network, and all transport through its transmission path. equipment. For example, SDH the network is on SDH. However, removes the need for back-to-back this is an ideal model that may not For the long term network devel- multiplexers/demultiplexers in be prevalent until well into the opment scenario, (when end-to- cross-connects and add/drop next century. At present, end SDH transmission is preva- multiplexers by enabling any and during this intervening period lent), the jitter performance of the customer payload to be located as the SDH network evolves, terminating PTE will be the main and tracked without the need to the hybrid synchronous/asynchro- contributor to jitter on the dismantle the multiple layers of nous network will predominate. demultiplexed tributary signal. hierarchy within the structure. Thus a signal may experience However, until reaching this stage However, due to the large inherent several synchronous/asynchro- of development, the network phase step associated with a nous conversions during its will become filled with SDH pointer movement (ie, 24UI per passage through the network. islands. A tributary signal's AU-4 pointer movement), com- transmission path may involve pared to that produced by pulse As SDH equipment is installed in traversing multiple SDH islands, stuffing techniques used in asyn- the network, SDH islands will and the problem of jitter accumu- chronous multiplexing, the SDH appear. Initially, these SDH lation will exist. network has the potential of islands are likely to be point-to- creating large jitter transients in point networks. As the SDH the demultiplexed tributary portions of the network increase, outputs. The need to characterize these islands will merge to form the jitter performance of