State Models For Network Elements (NEs)
A Network Element state model facilitates cross domain network management and promotes a multi-vendor environment. The standard definitions and mappings allow Operations Systems to gather state information from NEs and integrate it into a consistent representation of the status of the entire managed network and each of the services that it supports.
Telcordia GR-1093 discusses the two primary state models in industry. One is the Telcordia State Model, which consolidates the state models previously described in several Telcordia documents. By consolidating the models, changes and expansions to the models can be presented and can evolve in a coordinated fashion. Also, inconsistencies and redundancy may be averted. The other model is the International Standards Organization (ISO) State Model, which is defined in ITU-T Recommendation X.731.
The state of an entity represents the current condition of availability of the underlying resource or service in the NE from the point of view of management. In the context of the Telcordia State Model, the term “entity” represents an entry in a TL1 administrative view (i.e., represents the resource or service generally identified by the Access Identifier parameter). In the context of the ISO State Model, the term “entity” means “managed object.”
Different types of entities (such as hardware, transport facilities, and subscriber service) have a variety of state characteristics that express the availability of their underlying resources that are specific to each entity type. However, a state model is expected to be common to a large number of types of entities. It expresses key aspects of their availability at any given time. The purpose of the state model is to indicate the availability of an entity in providing its functions and, if an entity is not available, to indicate the cause of the unavailability and what kind of activity may be taken by the manager (e.g., the OS or the craft) to make the entity available.
In a specific application, only a subset of the state model may be needed. The rationale of such restrictions is not described in GR-1093. The technology or application-specific requirements document should be consulted for this information.
The standard definitions and mappings allow Operations Systems to gather state information from NEs and integrate it into a consistent representation of the status of the entire managed network and each of the services that it supports.
To help ensure interoperability, particularly for an OS that interfaces with multiple NEs using one of the two state models, a mapping between the models may be needed. GR-1093 provides a mapping for the two models and also defines the extension to the OSI state/status attributes that is necessary to meet the telecommunications needs of the service providers.
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