clear ip eigrp neighbors
This command immediately resets all EIGRP neighbor adjacencies, forcing the router to re-establish neighbor relationships and re-learn routes from all EIGRP neighbors.
clear ip eigrp neighborsWhen to Use This Command
- After changing EIGRP configuration parameters (e.g., K-values, hold timers) that require neighbors to re-negotiate.
- When troubleshooting EIGRP neighbor flapping or stuck-in-active (SIA) routes, to force a clean restart of neighbor relationships.
- To quickly recover from a network event where EIGRP routes are stale or incorrect, without reloading the router.
- During lab testing or network maintenance to simulate a full EIGRP reset and verify convergence.
Command Examples
Basic EIGRP neighbor reset
clear ip eigrp neighbors*Mar 1 00:05:23.123: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.2 (GigabitEthernet0/0) is down: cleared manually *Mar 1 00:05:23.124: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.0.0.2 (GigabitEthernet0/1) is down: cleared manually *Mar 1 00:05:28.456: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.2 (GigabitEthernet0/0) is up: new adjacency *Mar 1 00:05:28.789: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.0.0.2 (GigabitEthernet0/1) is up: new adjacency
The output shows syslog messages indicating each neighbor going down due to manual clear, then coming back up after the hold timer expires and hello packets are exchanged. The format includes timestamp, DUAL state change, neighbor IP, interface, and reason.
Clear neighbors on a specific interface
clear ip eigrp neighbors GigabitEthernet0/0*Mar 1 00:06:15.001: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.2 (GigabitEthernet0/0) is down: cleared manually *Mar 1 00:06:20.234: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.2 (GigabitEthernet0/0) is up: new adjacency
Only the neighbor on the specified interface is reset. The output shows the neighbor going down and then up after re-establishing adjacency.
Understanding the Output
The command does not produce a direct table output; instead, it triggers syslog messages (if logging is enabled) that show DUAL neighbor state changes. Each message includes a timestamp, the DUAL process identifier, the AS number, the neighbor IP address, the interface, and the reason for the change (e.g., 'cleared manually' or 'new adjacency'). In a real network, you would monitor these messages to confirm that neighbors reset and re-establish. After the clear, you can use 'show ip eigrp neighbors' to verify the neighbor table is repopulated. Good indicators are that all expected neighbors appear in the neighbor table with uptime counters resetting. Watch for neighbors that fail to come back up, which may indicate a configuration mismatch or connectivity issue.
CCNA Exam Tips
The command 'clear ip eigrp neighbors' is in Privileged EXEC mode, not global configuration.
On the CCNA exam, know that this command resets all EIGRP neighbors; to reset a specific neighbor, use 'clear ip eigrp neighbors [interface-type number]'.
Be aware that clearing neighbors causes temporary route loss and may impact traffic; it should be used carefully in production.
The exam may test that this command triggers DUAL events and that you can verify neighbor re-establishment with 'show ip eigrp neighbors'.
Common Mistakes
Using 'clear ip eigrp neighbors' in global configuration mode instead of Privileged EXEC mode.
Forgetting that this command clears all neighbors, not just one; using it unnecessarily can cause network disruption.
Assuming the command provides immediate output; it only generates syslog messages, so you must check logs or use 'show' commands afterward.
Related Commands
clear ip route *
Clears all entries from the IP routing table, forcing the router to rebuild the routing table from active routing protocols and directly connected networks.
show ip eigrp neighbors
Displays the neighbor table for EIGRP, showing all directly connected EIGRP routers and their status, used to verify EIGRP adjacencies and troubleshoot neighbor relationships.
show ip eigrp topology
Displays the EIGRP topology table, showing all learned routes and their feasible successors, used to verify EIGRP convergence and path selection.
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