This is the state of the database at this level: off means IS-IS is not active at this level, on means it is active and not overloaded, waiting means the database is low on an essential resource such as memory, and the administrator may force the state to overloaded via ciiSysLevelSetOverload. Seeing this report waiting rather than on is a direct signal the router itself is running low on an internal resource and may be about to self-declare overloaded, which would make other routers stop using it for transit even though it is still technically up. For example, a router reporting waiting during a memory leak or after receiving an unusually large number of LSPs is at risk of self-declaring overloaded and getting routed around before the admin even intervenes.