OSPF Basics

This tutorial introduces you to Open Shortest Path First (OSPF), a link-state routing protocol. You should know how to define a routing protocol and understand which protocol is best to use in your network. How to use and implement OSPF as the protocol of choice. However, you must also take an objective view of OSPF to understand why it is the best choice.

This tutorial helps you understand the basic types of routing protocols, their characteristics, when it is best to use a certain protocol, and how to use that information to build a deeper understanding of how to implement routing protocols in your network.However, each network has it own needs, but OSPF can almost always meet them. This tutorial covers the following objectives:

• What is a routing protocol?-This section discusses fundamental portions of understanding routing protocols, beginning with the difference between routed and routing protocols. You also learn about distance vector protocols and how they operate. In addition, this section extensively discusses the fundamentals of link-state protocols because OSPF falls within this category of protocols.
• Selecting a routing protocol-One of the most practical objectives required by all network designers is the ability to understand how to select a routing protocol. This section presents this information, comparing and contrasting three different routing protocols using real-world concerns.
• OSPF overview and functional environment-This section discusses the earliest appearance and creation of the shortest path first (SPF) algorithm and its evolution into the OSPF routing protocol. This functional environment of OSPF is a key element in understanding OSPF. It is within this environment that all discussions are based. This section discusses the following basic aspects of where and how OSPF functions:
  • Network types
  • Router identification
  • Adjacencies
  • Designated routers
  • Protocols within OSPF
  • Link-state advertisements
• OSPF routing hierarchy-OSPF's capability to perform as a hierarchical routing protocol makes it a good candidate in many large networks. As a result of this capability, OSPF supports a variety of techniques and designations that make operation much smoother. This section discusses the types of OSPF routers and hierarchical design techniques, including how OSPF separates a network into a hierarchy through the use of areas and autonomous systems.