You have designed a network to support two offices connected by a T1. Your router serial interfaces will be configured with encapsulation PPP. What will happen to your EIGRP neighbors if there is an…

EIGRP hold timer expiration only occurs when hello packets stop arriving on a still-active interface; an LCP failure causes the interface itself to go down, triggering immediate neighbor removal rather than a timer-based drop.

An LCP failure does cause the PPP link to go down at Layer 2, which EIGRP detects immediately through interface state change notifications.

While neighbors do drop immediately due to the interface-down event, this answer is incomplete because it omits the DUAL query process that EIGRP initiates to find replacement paths.

When PPP LCP fails, the interface is brought down at Layer 2, which EIGRP detects as an interface-down event rather than a hello timeout. EIGRP immediately removes the neighbor adjacency without waiting for hold timers to expire, then runs the DUAL algorithm and sends queries to remaining neighbors to find feasible successor routes for all affected prefixes.