OSPF Router ID
OSPF router ID is a unique 32-bit identifier used in OSPF operations and neighbor relationships.
Updated: 2026-03-06
Definition
OSPF uses a Router ID (RID) to identify routers in LSAs and neighbor adjacencies.
It is typically chosen from loopback IPs or highest active interface IP if not configured manually.
Key points
- Unique per OSPF router
- Often based on loopback interface
- Affects troubleshooting and stability
Common mistakes
- RID changes after reboot because no loopback was set (causes confusion).
- Duplicate router IDs in the same OSPF domain.
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