OSPF Path Selection types

Hi,

In this post I would like to give a simple note about OSPF path selection

some engineers wondering which one is correct?

RFC (1587)
Intra-Area(O) over Inter-Area(O IA) over External type (E1) over N1 over E2 over N2


OR


RFC (3101)
O over O IA over N1 over E1 over N2 over E2

well, both are correct, but according to your router ios version, because since (15.2S), Cisco started to use RFC3101 which uses O over O IA over N1 over E1 over N2 over E2 

while earlier software versions will use the Intra-Area(O) over Inter-Area(O IA) over External type (E1) over N1 over E2 over N2



Thanks