OSPF Basics

 

OSPF Route decision Process

Regardless of the metric or distance OSPF would prefer;

O – Intra-Area routes

OIA – Inter-Area route

E1 – External 1

E2 – External 2

N1 – NSSA type 1

N2 – NSSA type 2

E1 vs E2

E1 adds the metric every hop. E2 however, does not increment the metric when populating the routing table (this is the seed Metric). But routing decisions are made for equal metric exit points using the “forward Metric”

OSPF Area Types

Stub Area