debug ip eigrp summary
Use this command to display a summary of EIGRP neighbor adjacencies and route information, helping to quickly verify EIGRP operation and troubleshoot neighbor issues.
debug ip eigrp summaryWhen to Use This Command
- After configuring EIGRP on a router, verify that neighbors have formed adjacencies and routes are being exchanged.
- When troubleshooting EIGRP neighbor flapping, check the summary to see neighbor status and uptime.
- During network maintenance, confirm that all expected EIGRP routes are present and that the router is learning routes from the correct neighbors.
- When investigating routing loops or suboptimal paths, review the summary to identify the number of routes and their sources.
Command Examples
Basic EIGRP Summary Output
debug ip eigrp summaryIP-EIGRP: Neighbor 10.1.1.2 (GigabitEthernet0/0) is up: new adjacency IP-EIGRP: Neighbor 10.1.1.2 (GigabitEthernet0/0) is up: adjacency IP-EIGRP: Received update from 10.1.1.2 (GigabitEthernet0/0) with 5 routes IP-EIGRP: Sending update to 10.1.1.2 (GigabitEthernet0/0) with 3 routes IP-EIGRP: Neighbor 192.168.1.2 (Serial0/0/0) is up: new adjacency IP-EIGRP: Neighbor 192.168.1.2 (Serial0/0/0) is up: adjacency IP-EIGRP: Received update from 192.168.1.2 (Serial0/0/0) with 8 routes IP-EIGRP: Sending update to 192.168.1.2 (Serial0/0/0) with 3 routes
The output shows EIGRP neighbor events and route exchanges. 'Neighbor ... is up: new adjacency' indicates a newly formed neighbor relationship. 'Received update from ... with X routes' shows the number of routes learned from that neighbor. 'Sending update to ... with X routes' shows the number of routes advertised to that neighbor. This helps verify that neighbors are forming and exchanging routes.
EIGRP Summary with Route Changes
debug ip eigrp summaryIP-EIGRP: Neighbor 10.1.1.2 (GigabitEthernet0/0) is up: adjacency IP-EIGRP: Received update from 10.1.1.2 (GigabitEthernet0/0) with 5 routes IP-EIGRP: Sending update to 10.1.1.2 (GigabitEthernet0/0) with 3 routes IP-EIGRP: Route 192.168.2.0/24 added to topology table IP-EIGRP: Route 192.168.3.0/24 deleted from topology table
This output shows normal neighbor adjacency and route updates. Additionally, it indicates specific route changes: 'Route ... added to topology table' means a new route was learned, while 'Route ... deleted from topology table' means a route was removed. This helps track dynamic routing changes.
Understanding the Output
The 'debug ip eigrp summary' command provides real-time information about EIGRP neighbor state changes and route updates. Each line begins with 'IP-EIGRP:' followed by the event. For neighbor events, you see the neighbor IP address, interface, and status (e.g., 'is up: new adjacency' for first-time adjacency, 'is up: adjacency' for stable adjacency). For route updates, you see 'Received update from' with the neighbor and number of routes, and 'Sending update to' with the neighbor and number of routes. Additionally, individual route additions or deletions may appear as 'Route ... added to topology table' or 'Route ... deleted from topology table'. In a real network, you should see neighbor adjacencies form quickly after configuration. If you see repeated 'new adjacency' messages, it indicates flapping. A high number of route changes may indicate instability. Use this debug to confirm that EIGRP is exchanging routes as expected.
CCNA Exam Tips
CCNA exam tip: The 'debug ip eigrp summary' command is useful for verifying neighbor formation and route exchange, but remember that debug commands are CPU-intensive and should be used with caution in production.
CCNA exam tip: In the exam, you may be asked to interpret debug output to determine if EIGRP neighbors are forming correctly. Look for 'is up: adjacency' to confirm stable neighbors.
CCNA exam tip: Know that 'debug ip eigrp summary' shows only summary information; for detailed route information, use 'show ip eigrp topology'.
CCNA exam tip: Be aware that 'undebug all' or 'no debug ip eigrp summary' is used to disable debugging to avoid excessive CPU load.
Common Mistakes
Mistake 1: Leaving debug enabled after troubleshooting, which can cause high CPU usage and impact router performance. Always disable debug with 'undebug all' or 'no debug ip eigrp summary'.
Mistake 2: Confusing 'debug ip eigrp summary' with 'show ip eigrp summary'. The debug command shows real-time events, while the show command displays a static summary.
Mistake 3: Expecting to see route details in the summary debug output. This command only shows neighbor events and route counts, not specific route entries.
Related Commands
debug ip eigrp
This command enables real-time debugging of EIGRP packets and events on a Cisco router, used to troubleshoot EIGRP neighbor relationships, route exchanges, and metric calculations.
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.
undebug all
Disables all active debug operations on the router, used to stop debugging output and reduce CPU load.
Practice for the CCNA 200-301
Test your knowledge with hundreds of CCNA practice questions covering all exam domains.
Practice CCNA Questions