You can create a database of information that CSPF uses to compute one or more backup paths in case the primary path becomes unstable. The database describes the relationships between elements of the network, such as routers and links. Because these network elements share the same fate, this relationship is called fate sharing.
You can configure backup paths that minimize the number of shared links and fiber paths with the primary paths as much as possible to ensure that, if a fiber is cut, the minimum amount of data is lost and a path still exists to the destination.
For a backup path to work optimally, it must not share links or physical fiber paths with the primary path. This ensures that a single point of failure will not affect the primary and backup paths at the same time.
The following sections describe how to configure fate sharing and how it affects CSPF, and provides a fate sharing configuration example: