Frame Relay - for Faster and More Efficient Data Communications ...

51Fig. 23Inheritance hierarchy for PDH Termination PointsTTPCTPTrail Termination PointConnection Termination PointFig. 24PDH naming treeThe choice of transport Managed Objectsis illustrated in Fig. 21, which shows the InformationModel of a PDH 2/0.064 Mbit/sdemultiplexer. The figure is based on thereceive side of Fig. 11 and shows howManaged Objects and their possible locationsare derived from Transport Functions.The Resources in the vicinity of anend point of a Trail or a Connection can beassembled into a Managed Object. Thename of the Managed Object is related tothis end point.Fig. 22, which is based on Fig. 13, showsthe Information Model of a PDH 2/140Mbit/s multiplexer, multiplexing 64 separate2 Mbit/s signals into a 140 Mbit/s signaland vice versa. The multiplexer is connectedto adjacent equipment by means ofinterface cables.However, only those Managed Objectswhich are based on Resources are usablefor management. Table 3 lists Functions,Resources and Managed Objects relatedto the examples in Figs. 21 and 22. The tabletakes into account both transmissiondirections, whereas the figures are concernedwith only one direction.In PDH equipment, Resources normallyappear only in the receive side, leading to"SINK" type Managed Objects.The PDH Information Model can be usedto model, in a general way, all the differentkinds of PDH networks. This leads to theinheritance hierarchy shown in Fig. 23and to the Naming Tree shown in Fig. 24.The inheritance hierarchy consists of a genericpart and a PDH-specific part. EachERICSSON REVIEW No. 1-2, 1992