The number of prefices received from the neighbor that
are installed in the network instance RIB and actively used
for forwarding.
Routes that are actively used for forwarding are
defined to be those that:
- are selected, after the application of policies, to be
included in the Adj-RIB-In-Post, AND
- are selected by best path selection and hence installed
in the Loc-RIB (either as the only route, or as part of
a multipath set, AND
- are selected, after the application of protocol
preferences (e.g., administrative distance) as the
route to be used by the system's RIB