debug ip rip
Enables real-time debugging of RIP routing updates to troubleshoot routing issues by displaying sent and received RIP updates.
debug ip ripWhen to Use This Command
- Diagnosing why a RIP route is not being learned on a router
- Verifying that RIP updates are being sent and received correctly after configuration changes
- Troubleshooting RIP version mismatches or authentication failures
- Monitoring RIP updates during network convergence after a link failure
Command Examples
Basic RIP debug output
debug ip ripRIP: sending v2 update to 224.0.0.9 via GigabitEthernet0/0 (192.168.1.1)
RIP: build update entries
10.0.0.0/8 via 0.0.0.0, metric 1, tag 0
172.16.0.0/16 via 0.0.0.0, metric 2, tag 0
RIP: received v2 update from 192.168.1.2 on GigabitEthernet0/0
192.168.2.0/24 via 0.0.0.0 in 2 hops
10.0.0.0/8 via 0.0.0.0 in 3 hopsLine 1: Router sends RIP v2 update to multicast address 224.0.0.9 out of interface G0/0 with source IP 192.168.1.1. Line 2: Indicates building update entries. Lines 3-4: Routes being advertised: 10.0.0.0/8 with metric 1, 172.16.0.0/16 with metric 2. Line 5: Router receives a RIP v2 update from neighbor 192.168.1.2 on G0/0. Lines 6-7: Received routes: 192.168.2.0/24 with hop count 2, 10.0.0.0/8 with hop count 3.
RIP debug with triggered updates
debug ip rip eventsRIP: sending v2 update to 224.0.0.9 via GigabitEthernet0/0 (192.168.1.1) RIP: Update contains 2 routes RIP: Update queued RIP: Update sent via GigabitEthernet0/0 RIP: received v2 update from 192.168.1.2 on GigabitEthernet0/0 RIP: Update contains 1 routes RIP: Update processed
Line 1: Router sends RIP update. Line 2: The update includes 2 routes. Line 3: Update is queued for transmission. Line 4: Update sent successfully. Line 5: Router receives an update from neighbor. Line 6: Received update contains 1 route. Line 7: Update has been processed and routing table updated.
Understanding the Output
The debug ip rip command outputs real-time messages for each RIP update sent or received. Each line begins with 'RIP:' to indicate the protocol. For sent updates, it shows the interface, source IP, and the routes being advertised with their metrics and tags. For received updates, it shows the neighbor IP, interface, and the routes learned with hop counts. The metric (hop count) is critical: a metric of 16 means the route is unreachable. In a stable network, you should see periodic updates every 30 seconds. If updates are missing or contain unexpected routes, it indicates a problem. Watch for 'RIP: ignored v2 update from ...' which may indicate authentication failure or version mismatch. The output can be verbose; use 'undebug all' to stop debugging.
CCNA Exam Tips
CCNA exam tip: Remember that 'debug ip rip' can cause high CPU load on production routers; always use with caution and disable with 'undebug all'.
CCNA exam tip: The exam may ask you to interpret debug output to identify why a route is not being learned (e.g., metric 16, wrong interface, or access-list blocking).
CCNA exam tip: Know that RIP updates are sent every 30 seconds; if you don't see updates, check network connectivity or passive-interface configuration.
CCNA exam tip: Be aware that 'debug ip rip events' provides a less detailed but more CPU-friendly view compared to 'debug ip rip'.
Common Mistakes
Mistake 1: Leaving debug enabled after troubleshooting, causing performance degradation. Always use 'undebug all' or 'no debug ip rip'.
Mistake 2: Misinterpreting metric 16 as a valid route instead of unreachable. Metric 16 means the route is poisoned.
Mistake 3: Forgetting that RIP updates are sent to multicast 224.0.0.9; if multicast is blocked, updates won't be received.
Related Commands
show ip protocols
Displays the current state of all IP routing protocols running on the router, including timers, filters, and network advertisements.
show ip route
Displays the current IP routing table on a Cisco router, used to verify routes, check next-hop addresses, and troubleshoot connectivity issues.
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