Troubleshooting OSPFv2 - Troubleshooting OSPFv2 Neighbor Adjacencies
6 important questions on Troubleshooting OSPFv2 - Troubleshooting OSPFv2 Neighbor Adjacencies
What are the reasons an OSPFv2 Neighbor Adjacency migt not form?
- Interface is down
- Interface not running OSPF process
- Mismatched timers
- Mismatched area numbers
- Mismatched area type
- Different subnets
- Passive interface
- Mismatched authentication
- ACLs
- MTU mismatch
- Duplicate Router ID
- Mismatched network type
What three options are supported by OSPF for authentication?
- Null (Type 0, no authentication)
- Plaintext (Type 1, Credentials in plaintext)
- MD5 (Type 2, Send a Hash)
What three commands can be used to troubleshoot OSPF Authentication issues?
- Show IP OSPF
- Check if auth is enabled on the area
- Show IP OSPF Interface interface-type id
- Check if auth is enabled on the interface
- Check OSPF Authentication Key
- Debug IP OSPF Adj
- Show debug messages for mismatched authentication
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When do ACLs affect OSPF traffic?
- When applied inbound to an interface
- And prevents OSPF traffic
- Or traffic in general to OSPF multicast address
In what states do OSPF routers stay when there is an MTU mismatch?
In OSPF, when do mismatched Network Types form a problem and how can you check the type?
You can check the network type with the command:
Show IP OSPF Interface interface-type id
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