eigrp stub connected summary
Configures an EIGRP stub router to advertise only connected and summary routes, preventing it from being used as a transit router and reducing query scope.
eigrp stub connected summaryWhen to Use This Command
- Configuring a remote branch router that should only advertise its directly connected networks and any summary routes, not participate in full EIGRP routing.
- Limiting the routing table size on a spoke router in a hub-and-spoke topology by suppressing all other route advertisements.
- Preventing a low-end router from being used as a transit router for EIGRP traffic, reducing CPU and memory load.
- Controlling which routes are advertised from a stub router to the hub, ensuring only necessary prefixes are sent.
Command Examples
Basic stub configuration with connected and summary
router eigrp 100
eigrp stub connected summaryR1(config-router)#router eigrp 100 R1(config-router)#eigrp stub connected summary %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.0.0.2 (GigabitEthernet0/0) is up: new adjacency R1(config-router)#
The command enables EIGRP stub mode for process 100, advertising only connected and summary routes. The output shows a neighbor adjacency reset and re-establishment, confirming the stub configuration took effect.
Verifying stub configuration
show ip eigrp neighbors detailEIGRP-IPv4 Neighbors for AS(100)
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 10.0.0.2 Gi0/0 13 00:12:34 1 200 0 45
Version 12.0/2.0, Retrans: 0, Retries: 0, Prefixes: 3
Topology-ids from peer - 0
Stub Peer Advertising (CONNECTED SUMMARY) Routes
Suppressing queriesThe 'Stub Peer Advertising (CONNECTED SUMMARY) Routes' line confirms the neighbor is a stub router advertising only connected and summary routes. 'Suppressing queries' indicates the hub will not send queries to this neighbor, reducing query scope.
Understanding the Output
The 'show ip eigrp neighbors detail' output reveals stub status. Look for 'Stub Peer Advertising' followed by the route types (CONNECTED, SUMMARY, etc.). If you see 'Suppressing queries', the stub router will not receive EIGRP queries, which is expected. A missing 'Stub Peer' line means the router is not configured as a stub. In 'show ip eigrp topology', stub routers will only have entries for their own connected and summary routes; they will not learn external routes. Good values: stub routers have small routing tables and low CPU. Bad values: if a stub router shows many routes, it may be misconfigured or leaking routes. Watch for 'eigrp stub' without keywords, which defaults to connected and summary only.
CCNA Exam Tips
CCNA exam tip: The 'eigrp stub' command defaults to 'connected' and 'summary' if no keywords are specified.
CCNA exam tip: Stub routers reduce query scope and prevent transit traffic; they are commonly used at branch sites.
CCNA exam tip: The 'receive-only' keyword prevents the stub from advertising any routes, useful for pure leaf nodes.
CCNA exam tip: Remember that stub routers do not form neighbor relationships with other stub routers; they only connect to hub routers.
Common Mistakes
Mistake 1: Forgetting to include 'connected' or 'summary' keywords, causing the stub to advertise only default routes (if configured) or nothing.
Mistake 2: Configuring 'eigrp stub' on a hub router, which can break routing because the hub will not advertise routes to other spokes.
Mistake 3: Using 'eigrp stub' without understanding that it suppresses queries; if the stub has a backup link to another stub, queries may be lost.
Related Commands
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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