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OSPF Type-5 Missing: show ip ospf database external When Redistribution Is Silent

Aug 15
2 min read
Cisco routing network security troubleshooting lab
Cisco routing · Techclick CLI troubleshooting lab
You redistributed BGP into OSPF. Internal routers never see the prefixes. ASBR looks fine.

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

Type-5 only exists if the ASBR actually redistributes and the area is not a stub/NSSA without translation.

Why this ticket shows up

A stub area will not carry type-5. An NSSA needs type-7 to type-5 translation on the ABR.

Symptoms operators actually see

  • No type-5 on internals

  • ASBR has the BGP routes

  • Area is stub or NSSA

  • subnets keyword missing

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 ospf database external
show ip ospf database nssa-external
show ip ospf
show ip route ospf
show ip ospf border-routers

How to read that output

If the area is stub, type-5 cannot appear. If NSSA, look for type-7 and a translator ABR.

Triage order

  1. Identify area type

  2. On ASBR, confirm redistribute with subnets

  3. On ABR, confirm translation if NSSA

  4. Do not turn every area into backbone casually

  5. Verify type-5 on an internal router

Classic traps

What you see

Real cause

Fix

Add more redistribute

Area is stub

Change area type or design

Default-information originate only

You needed specific prefixes

Redistribute correctly

Put the ASBR in two areas wrongly

You created a surprising ABR

Draw the areas

Proof the ticket is closed

  • type-5 or translated type-5 present

  • Internal router has the prefixes

  • No routing loop

Say this in an interview

Missing type-5 makes me ask the area type before I touch redistribute.

Need the full vendor lab, mock interview, and production runbooks? Techclick trains Palo Alto, Zscaler, F5, FortiGate, Check Point, Cisco ISE, Azure and routing with live CLI — start at https://www.techclick.in/

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