Real-world CLI verification commands with expected healthy outputs and failure indicators. Deep dive into DUAL topology tables, successor/feasible successor verification, and SIA diagnostics. Use this checklist during lab work or production troubleshooting.
| Command | Expected Output (Healthy) | Failure Indicator |
|---|---|---|
show ip eigrp topology |
P 10.1.10.0/24, 1 successors, FD is 158720 via 10.1.12.2 (158720/156160), Gi0/1 via 10.1.13.2 (2300416/156160), Gi0/2 P 10.1.20.0/24, 1 successors, FD is 158720 via 10.1.13.2 (158720/156160), Gi0/2 via 10.1.12.2 (2300416/156160), Gi0/1 Each destination shows 1 successor + 1 feasible successor |
P 10.1.10.0/24, 0 successors, FD is Inaccessible via 10.1.12.2 (158720/156160), Gi0/1 via 10.1.13.2 (2300416/156160), Gi0/2 0 successors = no valid path. Route is down. |
show ip eigrp topology all-links |
P 10.1.10.0/24, 1 successors, FD is 158720 via 10.1.12.2 (158720/156160), Gi0/1 via 10.1.13.2 (2300416/156160), Gi0/2 via 10.1.13.2 (307200/158720), Gi0/2 ← Alternate (fails Feasibility) All paths visible. Feasible and non-feasible both shown. |
P 10.1.10.0/24, 1 successors, FD is 158720 via 10.1.12.2 (158720/156160), Gi0/1 (no other paths listed) Only successor present. No backup path exists. |
show ip eigrp topology active(empty output — no routes in Active state)
Ideal state. All routes are Passive.
IP-EIGRP Topology Table for AS(1234)/ID(1.1.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply A 10.1.10.0/24, 0 successors, FD is Inaccessible via 10.1.12.2 (Infinity/Infinity), Gi0/1 via 10.1.13.2 (Infinity/Infinity), Gi0/2
A = Active state. Router has lost successor and is querying neighbors. SIA risk.
show ip eigrp eventsEvent information for AS 1234: 1 19:42:15.123 Poison squashed: 10.1.10.0/24 2 19:42:14.988 Route install: 10.1.10.0/24 3 19:42:14.855 Changing RIB state for 10.1.10.0 4 19:42:14.722 Rcv reply from 10.1.12.2 5 19:42:14.601 Query origination: 10.1.10.0
Query sent, reply received, route installed. Normal convergence.
Event information for AS 1234: 1 19:42:15.123 SIA Query origination: 10.1.10.0 2 19:42:14.988 Query origination: 10.1.10.0 3 19:42:14.855 Route active: 10.1.10.0/24 4 19:45:15.001 All neighbors Stuck-In-Active
SIA event detected. Neighbor did not reply within Active timer (3 min).
Every line in show ip eigrp topology shows two numbers in parentheses. Understanding them is essential for reading DUAL state.
P 10.1.10.0/24, 1 successors, FD is 158720
via 10.1.12.2 (158720/156160), GigabitEthernet0/1
^ ^
| |
CD (this) RD (neighbor reports)
| Metric | Meaning | Where It Comes From |
|---|---|---|
| FD (Feasible Distance) | The best (lowest) cumulative metric seen to this destination | Top line after "FD is" |
| CD (Cumulative Distance) | Total metric from this router to destination via this neighbor | First number in parentheses |
| RD (Reported Distance) | Metric the neighbor advertised to reach this destination | Second number in parentheses |
For each path in the topology table:
router eigrp 1234 eigrp stub connected summary ! Advertises connected + summary routes ! Does NOT forward queries to other stub routers ! Does NOT accept queries from non-stub peers in stub sub-tree ! Verify stub status ! show ip protocols | section Stub ! show ip eigrp neighbors detail
interface GigabitEthernet0/0 ip summary-address eigrp 1234 10.16.0.0 255.255.240.0 ! Summary route 10.16.0.0/20 advertised to EIGRP neighbors ! Automatically installs Null0 discard route (AD 5) ! Queries for specific /24s inside 10.16.0.0/20 stop here ! Verify summary ! show ip route | include Null0 ! show ip eigrp topology | include summary
! After implementing stub + summarization: show ip protocols | include Stub ! Should show: EIGRP stub, receive-only/connected/summary show ip eigrp topology summary ! Should show reduced query-domain reachability debug eigrp packets query ! Query for a summarized prefix should NOT reach stub routers ! Verify stub routers do not generate or forward queries
show ip route that traffic follows the intended path.