OSPF Overview

The Open Shortest Path First version 2 (OSPF) protocol is an interior gateway protocol (IGP) that routes packets within a single autonomous system (AS). OSPF uses link-state information to make routing decisions.

In this document, the term OSPF refers to both OSPFv2 and OSPFv3.

This chapter discusses the following topics that provide background information about OSPF:

• OSPF Protocol Overview
• OSPF Standards
• OSPF Area Terminology
• OSPF Routing Algorithm
• OSPF Packets
• External Metrics
• Designated Router
• OSPF Extensions to Support Traffic Engineering

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