ch install on the network element needs to be notified to the inventory management system. There are products solely developed for inventory management in telecom industry. 4.5 Integrated Multivendor Environment At the Network Operations Center (NOC) only a single interface is provided to the operator to work on the underlying network. This is an integrated multivendor environment where the underlying network would contain network elements from different vendors and the network management system would have the capability to invoke any element management system for a specific network element. In most scenarios when an element manager for a NE is launched from the NMS, the ele- ment manager and the network manager application can be open simultaneously. With hundreds of network elements and its resources that make up the network, it is not practical to have separate applications handling each of the NEs and an operator going to the trouble of browsing through these applications to find the network health. With an integrated view of the entire network and centralized control, much of the overhead involved in handling a multivendor environment is reduced. There is normalization to be performed on the data from a different element management system before it can be handled by a single NMS application. This nor- malization is performed by the adaptation layer, which performs the conversion to a common format (see Figure 4.2). The adaptation layer can be a separate application or it can be implemented as part of the EMS or in the NMS. That is, each vendor who sells an EMS also provides the adaptation application or a probe for the NMS to collect data from EMS, or the NMS developer adds an adapter for a specific EMS each time it buys a new network element and its element management solution. The functions in a network management system involve actions that can be per- formed on all the network elements. To have a common set of functions applicable EMS Functions Network management system Adaptation layer EMS-a EMS-b EMS-c