The black box classes allow the topology to show unmanaged segments of the network and to provide root-cause and impact analysis for networks containing the black boxes.

In the case of a black box, entities are not managed for administrative or technical reasons, not due to a network failure. A black box, for example, may be a leased line that you do not manage between network segments that you do manage. It may also be a leased line at the edge of your managed network.

A black box cannot be discovered. It is created using APIs provided with Optical Transport Manager. An API, along with a flat file or database, can create the black box classes.

The black box may be a “black box cloud,” containing multiple unmanaged devices. As long as there are no intervening managed network elements, all the adjacent devices and connections are part of one black box.

Black boxes appear as unmanaged subnetworks in the topology, identified by its endpoints, connected directly to the edges of the managed segments. They are represented as BBTopologicalLink or BBDropSideTopologicalLink classes in the SONET/SDH repository.

The BBDropSideTopologicalLink (BBDSTL) represents an edge unmanaged network entity or segment in the SONET/SDH network.

Figure 1. Edge SONET black box

The BBTopologicalLink (BBTL) represents an in-line unmanaged network entity or segment in the SONET/SDH network.

Figure 2. In-line SONET black box

As part of a TopologicalLinkGroup, the black box objects can be part of a 1+1 automatic protection switching group. “1+1 automatic protection switching” on page 97 provides more details.