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.
show ip eigrp topologyWhen to Use This Command
- Troubleshooting missing routes in an EIGRP network by checking if the route is in the topology table.
- Verifying feasible successor routes for fast convergence after a link failure.
- Checking the metric and successor status for a specific prefix to understand path selection.
- Monitoring EIGRP topology changes during network maintenance or after configuration changes.
Command Examples
Viewing the entire EIGRP topology table
show ip eigrp topologyIP-EIGRP Topology Table for AS(100)/ID(10.0.0.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 192.168.1.0/24, 1 successors, FD is 28160
via 10.0.0.2 (28160/2816), GigabitEthernet0/0
via 10.0.0.3 (30720/2816), GigabitEthernet0/1
P 10.0.0.0/8, 1 successors, FD is 28160
via 10.0.0.2 (28160/2816), GigabitEthernet0/0
P 172.16.0.0/16, 1 successors, FD is 30720
via 10.0.0.3 (30720/2816), GigabitEthernet0/1Line 1: Shows AS number and router ID. 'P' means route is passive (stable). '192.168.1.0/24' is the destination network. '1 successors' indicates one best path. 'FD is 28160' is the feasible distance. Each 'via' line shows next-hop IP, (computed metric/reported distance), and outgoing interface.
Viewing topology for a specific network
show ip eigrp topology 192.168.1.0/24IP-EIGRP topology entry for 192.168.1.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 28160
Routing Descriptor Blocks:
10.0.0.2 (GigabitEthernet0/0), from 10.0.0.2, Send flag is 0x0
Composite metric is (28160/2816), Route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 200 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
10.0.0.3 (GigabitEthernet0/1), from 10.0.0.3, Send flag is 0x0
Composite metric is (30720/2816), Route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 300 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1Shows detailed topology entry for a specific prefix. 'State is Passive' means route is stable. 'FD is 28160' is feasible distance. Each Routing Descriptor Block shows a path with next-hop IP, interface, composite metric (FD/RD), and vector metrics (bandwidth, delay, reliability, load, MTU, hop count). The path with lower metric (28160) is the successor.
Understanding the Output
The 'show ip eigrp topology' output lists all EIGRP-learned routes. Each entry starts with a code: 'P' (Passive) means the route is stable; 'A' (Active) means the router is actively querying for a route (potential issue). The destination network is followed by the number of successors (best paths) and the Feasible Distance (FD). Each path shows the next-hop IP, the composite metric (FD/reported distance from neighbor), and the outgoing interface. The composite metric is calculated from bandwidth, delay, reliability, load, and MTU. A lower FD indicates a better path. The reported distance (RD) is the distance advertised by the neighbor; for a route to be a feasible successor, the RD must be less than the FD. In a healthy network, all routes should be Passive. Active routes indicate convergence issues. Watch for high metrics or multiple successors indicating load balancing.
CCNA Exam Tips
CCNA exam tip: Remember that 'P' stands for Passive (stable) and 'A' for Active (querying). Active routes often appear in exam troubleshooting questions.
CCNA exam tip: The Feasible Distance (FD) is the metric of the best path; the Reported Distance (RD) is the metric advertised by the neighbor. For a feasible successor, RD must be less than FD.
CCNA exam tip: EIGRP uses DUAL algorithm; the topology table holds all routes, while the routing table only holds the successor(s).
CCNA exam tip: In the output, 'via' lines show all paths; the first one is usually the successor. Multiple successors indicate equal-cost load balancing.
Common Mistakes
Mistake 1: Confusing the topology table with the routing table. The topology table shows all EIGRP routes, while the routing table shows only the best routes installed.
Mistake 2: Ignoring the route state (Passive vs Active). An Active route indicates a query in progress, which can cause network instability.
Mistake 3: Misinterpreting the composite metric values. The metric is a composite of bandwidth and delay by default; other K-values may be used but are rare.
Related Commands
show ip eigrp interfaces
Displays detailed information about interfaces on which EIGRP is enabled, including neighbor status, pending routes, and interface statistics, used to verify EIGRP adjacency and interface participation.
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 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.
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