OSPF Path selection
RFC 1587 states that OSPF used the following path selection order when choosing a path:
- Intra-Area (O)
- Inter-Area (O IA)
- External Type 1 (E1)
- NSSA Type 1 (N1)
- External Type 2 (E2)
- NSSA Type 2 (N2)
RFC 3101 has since revised this order to:
- Intra-Area (O)
- Inter-Area (O IA)
- NSSA Type 1 (N1)
- External Type 1 (E1)
- NSSA Type 2 (N2)
- External Type 2 (E2)
Cisco IOS version 15.1(2)S and later adheres to the RFC3101 order while earlier versions adhere to the RFC1587 order
Links:
https://networklessons.com/ospf/ospf-path-selection-explained/