%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.1.2 (GigabitEthernet0/0) is down: holding time expired
In plain English: EIGRP, Cisco's routing protocol, lost a neighbor.
Platform: Cisco IOS / IOS XE routers. The 15-second hold time in this entry is the usual default on LAN interfaces.
What it means
EIGRP, Cisco's routing protocol, lost a neighbor. 'Holding time expired' means this router heard nothing from that neighbor for the full hold window — usually 15 seconds. The routes learned through that neighbor are withdrawn and traffic re-routes, so a single drop is an event; repeated drops mean the path or the neighbor is sick.
Likely causes, in order
The neighbor rebooted or its interface failed.
The link between them drops EIGRP's hello packets — congestion, a failing optic, or a wireless bridge misbehaving.
Someone filtered multicast traffic (EIGRP hellos go to 224.0.0.10) with an ACL or a security change.
The neighbor is so CPU-starved it cannot send hellos on time.
Check, in order
show ip eigrp neighborsWhich neighbors are up, their hold times, and whether one keeps resetting (watch the uptime column).
show interfaces Gi0/0Errors and drops on the interface facing the neighbor.
show logging | include DUALHow often this exact neighbor drops, and whether the reason is always the same.
The fix
Restore the path: fix the physical errors or remove the filter blocking the hellos.
If the neighbor drops under load, address its CPU or the link congestion rather than stretching timers first.
Verify with show ip eigrp neighbors: uptime counting steadily upward, no new NBRCHANGE lines.
Did this fix it for you? One tap — anonymous, nothing to type, and nothing you send is ever published.
Thanks — your tap helps the next engineer. A run of "still broken" reports sends this page back to the top of our re-check list.