Network Management Functions:

Classically, network management consists of several functions, all of which are important to the operation of the network:

1. Performance management deals with monitoring and managing the various parameters that measure the performance of the network. Performance management is an essential function that enables a service provider to provide quality-of-service guarantees to their clients and to ensure that clients comply with the requirements imposed by the service provider. It is also needed to provide input to other network management functions, in particular, fault management, when anomalous conditions are detected in the network.

2. Fault management is the function responsible for detecting failures when they happen and isolating the failed component. The network also needs to restore traffic that may be disrupted due to the failure, but this is usually considered a separate function.

3. Configuration management deals with the set of functions associated with managing orderly changes in a network. The basic function of managing the equipment in the network belongs to this category. This includes tracking the equipment in the network and managing the addition/removal of equipment, including any rerouting of traffic this may involve and the management of software versions on the equipment.

Another aspect of configuration management is connection management, which deals with setting up, taking down, and keeping track of connections in a network. This function can be performed by a centralized management system. Alternatively, it can also be performed by a distributed network control entity. Distributed network control becomes necessary when connection setup/take-down events occur very frequently or when the network is very large and complex.

Finally, the network needs to convert external client signals entering the optical layer into appropriate signals inside the optical layer. This function is adaptation management.

4. Security management includes administrative functions such as authenticating users and setting attributes such as read and write permissions on a per-user basis. From a security perspective, the network is usually partitioned into domains, both horizontally and vertically. Vertical partitioning implies that some users may be allowed to access only certain network elements and not other network elements.

• For example, a local craftsperson may be allowed to access only the network elements he is responsible for and not other network elements.

  Horizontal partitioning implies that some users may be allowed to access some parameters associated with all the network elements across the network.

• For example, a user leasing a lightpath may be provided access to all the performance parameters associated with that lightpath across all the nodes that the light path traverses. Security also involves protecting data belonging to network users from being tapped or corrupted by unauthorized entities. This part of the problem needs to be handled by encrypting the data before transmission and providing the decrypting capability to legitimate users.

5. Accounting management is the function responsible for billing and for developing lifetime histories of the network components. This function is the same for optical networks.