Provisioning applications are concerned with driving desired configurations down to network devices; for example, to turn up a service for a customer in the network. Using network management parlance, we also refer to network devices as network elements, as depicted in Figure 1-8. To perform provisioning, a management system typically sends a request, or a number of requests, to a network element, or a set of network elements, and processes the responses returned from the network to make sure everything is in order. These interactions with the network devices constitute transactions that are conducted with the network.
Figure 1-8 Network and Network Elements
This means that a provisioning application shares many characteristics with transaction-based systems in other areas, such as banking. As with a transaction-based system in those other areas, a provisioning application must be good at dispatching requests, processing responses, managing jobs, and keeping track of the workflow. (Of course, some differences also exist. For example, unlike in a banking application, the provisioning application needs to deal with devices in a network that in some sense have a life of their own. Changes in the network element's state can occur unexpectedly, outside the control of the operations support infrastructure. Likewise, unlike with bank transactions, some of the operations that are performed might have effects that are potentially impossible to undo, such as when a reset occurs or a line is blocked that causes a glitch in service for some customer.)
Figure 1-9 depicts the role of a management application used for provisioning in simplified fashion. Roughly speaking, the application first confirms that the request for a new service is filled out correctly and identifies which pieces of network equipment are needed to fulfill the request. It then sends a series of configuration commands to the devices that are involved. Finally, it confirms that the newly provisioned service is working. If any errors occur during execution of the transaction, the provisioning application must perform any needed rollback operations to bring the network back to a well-defined state.
Figure 1-9 Network Provisioning
1. Validate request, identify resources 4. Status update, service ready
2. Configure/ \ 3. Configure CPE / \ Aggregation
Customer Premise Equipment
Few people would consider a bank transaction system that must serve automatic teller machines in thousands of locations for hundreds of thousands of customers and their associated bank accounts to be trivial. Compare this with a provisioning application that must serve hundreds of operators for tens of thousands of network elements. The numbers for the provisioning application might be an order of magnitude smaller, but consider now that the network elements might comprise dozens of different equipment types and technologies, and support service for hundreds of thousands of customers, each requiring a distinct set of parameters to be configured properly to obtain service.
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