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

Fig. 4The telecommunication network can be consideredto be divided intoa the physical transmission networkb the logical transport networkcdDESDXCLSTANTNSSPSCPFNUwsOSQthe intelligent services networkthe telecommunication managementnetwork (TMN)Digital ExchangeSynchronous digital cross-connect equipmentLine SystemTerminalAccess NodeTransit NodeService Switching PointService Control PointFeature NodeUserWorkstationOperating SystemInterface between the Transmission ManagementNetwork and the Managed ObjectsIn a follow-up article, the derivation of ManagedObjects for other aspects will be presented.No attempt is made in this articleto define the Managed Objects in detail,since the standards referred to give completedefinitions of the objects in question.A layered view of thetelecommunication networkBasically, networks and their managementare described according to the principle ofdividing complex problems into less complexones, which can be solved independentlyof each other. Partial solutions cancontribute in an iterative manner to the solutionof a complex problem.If these principles are followed, the telecommunicationprocess can be allocatedto various networks, Fig. 4,- the physical transmission network- the logical transport network- the intelligent services network (IN)-the telecommunications managementnetwork (TMN).In addition to the telecommunication functions,each of the networks also containsfunctions for network management. ManageableResources are represented byManaged Objects in the Information Model.The Transmission Network, Fig. 4a, containsthe physical means of transfer of information,i.e. telecommunications equipmentand connecting transmission media:typically, switching matrices of switchesand cross-connect systems, modems,muldexes, line systems and cables. Thetransmission network contains varioustransmission network layers, as specifiedin Recommendations G.702 and G.707,for example. 5 Typical physical managementresources that are part of the transmissionnetwork are: signal level detectors,error counters and error informationstorage.The Transport network, Fig. 4b, performslogical functions related to transmission,such as network configuration and protectionswitching, and ensures reliable transferof information between service users,regardless of the information content. Thetransport network contains various TransportNetwork Layers, each of which carriesa distinct characteristic signal, i.e. a signalwith a particular data rate and format. 2Manageable Resources are the functionalrepresentations of the physical resourcesimplemented in the transmission network.The Service network, Fig. 4c, performsfunctions related to switching and signalling.The purpose of the intelligent ServiceNetwork is to offer users a particular service.The user initiates a service via a ServiceSwitching Point (SSP) using signallingsystem No. 7 or D-channels of theISDN system. The service also needs datafrom a Feature Node (FN). The process iscontrolled by the database of the ServiceControl Point (SCP). 6 Typical ManageableResources are concerned with traffic management,customer services and manyother management functions related toswitching and signalling.The Telecommunications ManagementNetwork (TMN), Fig. 4d, connects the networkoperators and administrators - viaworkstations (WS), operation systems(OS) and standardised Q-interfaces - toManaged Objects which represent the resourcesin the various networks. 3 For themanagement of TMN, typical resourcesare concerned with communicationchecks and protocol conversions.ERICSSON REVIEW No. 1-2, 1992