3.5.d [iv] Graceful shutdown
With graceful shutdown, a goodbye message is broadcast when an EIGRP routing process is shutdown, to inform adjacent peers about the impending topology change. This feature allows supporting EIGRP peers to synchronize and recalculate neighbour relationships more efficiently than would occur if the peers discovered the topology change after the hold time expired.
EIGRP sends an interface goodbye message with all K values set to 255 towards neighbors connected to its different interfaces. If the IOS neighbor router supports this graceful shutdown then it says “interface goodbye received”. If not, it says K values mismatch.
Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3172-3178). . Kindle Edition.