OSPF Routes Not Appearing in Routing Table: Troubleshooting

Common Causes

1. Better Administrative Distance

Problem: Another routing protocol has better AD

Example:

• EIGRP (AD 90) beats OSPF (AD 110)

Check:

R1# show ip route 192.168.10.0
D    192.168.10.0/24 [90/2816] via 10.1.1.2  ← EIGRP won

Solution: Remove other protocol or adjust AD

2. Passive Interface

Problem: Interface advertising route is passive (can't be next-hop)

Check:

R1# show ip protocols | include Passive
  Passive Interface(s):
    GigabitEthernet0/1  ← Next-hop interface is passive

Solution: Remove passive if interface needs to forward

3. Route Filtering

Problem: Distribute-list blocking route

Check:

R1# show ip protocols | include distribute-list
  Distribute list 10 in from 2.2.2.2

Solution: Check ACL 10, remove filter if incorrect

4. Inactive Next-Hop

Problem: Next-hop IP not reachable

Check routing table for next-hop

Solution: Fix next-hop reachability

Verification Steps

1. Confirm Route in LSDB

R1# show ip ospf database | include 192.168.10.0

2. Check for Better Route

R1# show ip route 192.168.10.0

3. Check OSPF SPF Log

R1# show ip ospf | include SPF

Summary

✅ Check LSDB — Route should be there
✅ Check AD — Other protocol may win
✅ Check passive — Interface may be passive
✅ Check filtering — Distribute-list may block

Next: Passive Interface Mistakes (Article 24)

Internal Links:

• ← Authentication Mismatch (Article 21)
• ← OSPF Cost (Article 6)
• → Passive Interface Mistakes (Article 24)