In order to become neighbors, routers perform several checks. If this check fails, we have to troubleshoot and find the cause of this issue. You will find below several examples of neighbor failed. I have added logs messages and debug messages in order to easily find the cause.
- Area mismatch:
- Authentication key mismatch:
- Duplicate Router-id:
- Subnet/mask Mismatch:
- Area Type Mismatch:
