EIGRP Stuck-Active: show ip eigrp topology When a Query Never Comes Home

Cisco routing · Techclick CLI troubleshooting lab

A prefix flaps into Active. After three minutes routes drop. Users scream in one building.

This is a live-ticket style lesson from Techclick Infosec. You will isolate the fault with CLI first, then prove the fix with one clean packet or log.

What you will be able to do

• Name the first CLI command to run on Cisco routing for this ticket

• Separate the layer that is actually broken from the layer people blame

• Apply one scoped fix instead of a global disable

• Prove the ticket closed with a session, log, or counter

Quick answer

Stuck-in-Active means a query was not answered. Find the neighbor that did not reply and fix that link or stub it.

Why this ticket shows up

EIGRP queries the entire domain unless you stub or summarize. A slow or broken spoke holds the query.

Symptoms operators actually see

• SIA errors

• One prefix Active

• WAN spoke with no stub

• No summary at the hub

CLI first — copy this block

Run these on the Cisco routing device or console named in the ticket. Do not skip the first show command — it tells you which later command matters.

show ip eigrp topology
show ip eigrp topology 10.50.0.0/16
show ip eigrp neighbors
show logging | include DUAL-5-NBRCHANGE|SIA
show ip eigrp traffic

How to read that output

The topology entry names who was queried. The neighbor that never answered is your spoke or your congested WAN.

Triage order

1. Identify the Active prefix

2. See which neighbor did not reply

3. Fix that link or configure eigrp stub on spokes

4. Summarize at the hub

5. Watch SIA disappear

Classic traps

What you see	Real cause	Fix
Raise SIA timer forever	You hide a broken spoke	Fix the spoke
Redistribute into BGP to escape	Queries still flood	Stub/summarize
Reload the hub	Spoke still will not answer	Same SIA

Proof the ticket is closed

• Prefix Passive/stable

• No SIA logs

• Spokes are stub or summarized

Say this in an interview

SIA is a query-scope problem. I stub and summarize before I touch timers.

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