An airport authority wants to nudge EIGRP traffic away from a congested microwave hop during fair season without tearing down the adjacency. Which tool best applies a controlled metric increase to selected prefixes?

EIGRP offset-lists add a configured metric offset to matching routes inbound or outbound, enabling controlled traffic engineering without removing the adjacency. An airport authority that wants to nudge traffic away from a congested microwave hop during fair season without tearing down the neighbor should apply an offset-list that adds metric to matching prefixes in or out on the affected path. Offset-lists remain a classic operations tool for seasonal or temporary nudges on civic microwave and backup radio links when tearing down peering would be disproportionate.

Passive-interface on the microwave link stops routing exchange and adjacency on that interface—far more destructive than a controlled metric nudge and likely to blackhole rather than gently shift load. Changing the OSPF process ID on EIGRP routers is irrelevant to EIGRP path choice and confuses IGP identity with traffic engineering. Disabling BFD so failures are detected more slowly does not steer traffic away from congestion and weakens failure detection when the microwave actually fails.

Exam caveat: offset-lists change composite metrics and can affect feasibility conditions for backups; apply narrowly with an ACL matching only the intended prefixes and remove the offset after the event. Operational check: measure traffic on microwave versus alternate paths before and after the offset, confirm adjacency stays up, verify only matched prefixes shift next hops, and schedule removal when fair-season congestion ends.