OSPF

OSPF is a link-state routing protocol that uses areas and SPF to compute routes.

Updated: 2026-03-05

Definition

OSPF (Open Shortest Path First) is a dynamic routing protocol that builds a topology map using LSAs and calculates best paths using the SPF algorithm.

It supports hierarchical design using areas to scale.

Key points

Link-state routing protocol
Uses areas (Area 0 backbone)
Neighbors form adjacencies and exchange LSAs

Common mistakes

Area design errors (backbone connectivity issues).
Mismatched OSPF parameters preventing adjacency.

Related exams

Cisco CCNA (200-301)

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Related terms

what is routing
what is subnetting

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