 NMS type 2 NMS type 1 Existing external applications Figure 34.5 Use of mediation layer. creating an NGNM framework as discussed in the previous sections, for future enhancements when adding functions or supporting new networks and integrated the existing legacy NMS solutions to a single GUI of NGNM framework by writing adapters for the existing legacy applications to plug-in to the NGNM framework In this approach a mediation layer is used by existing applications to interact with the NGNM framework (see Figure 34.5). This mediation layer contains a pool of interface and data/information adaptors. There can be different protocols that collect data from the applications that interact with the NMS. Conversion in data format is required SO that the NMS can work on the data, and the interface or lan- guage of interaction needs to be based on the interface model supported by NMS. So a conversion might be required if the application does not already support the interface and information model. The adapters need to be written for the external application that interacts with the unified NMS. This way a single NMS triggers commands and gets results from the different external applications and presents the output on a single GUI. Management of new networks or addition of new functionalities will be supported without using any adapters in the NMS framework. This adoption approach was used by TMF to demonstrate how legacy/custom- ized NMS solutions can interface with standards based frame in its openOSS cata- lyst project. The mediation approach is most popular in the service provider space where there are multiple NMS solutions being put to use to manage the different net- works. The service provider would want to integrate the functionalities in the dif- ferent NMS solutions to a single GUI to make network operations support more convenient and reduce the overhead on the technicians. 34.6.2 Staged Migration This approach is suitable when a single legacy NMS is used for managing the networks. This is mostly the case with n