IPC-223
Cisco IOS IP Configuration Guide
Configuring OSPF
This chapter describes how to configure Open Shortest Path First (OSPF). For a complete description of
the OSPF commands in this chapter, refer to the “OSPF Commands” chapter of the CiscoIOS IP
Command Reference, Volume 2 of 3: Routing Protocols publication. To locate documentation of other
commands that appear in this chapter, use the command reference master index, or search online.
OSPF is an Interior Gateway Protocol (IGP) developed by the OSPF working group of the Internet
Engineering Task Force (IETF). Designed expressly for IP networks, OSPF supports IP subnetting and
tagging of externally derived routing information. OSPF also allows packet authentication and uses IP
multicast when sending and receiving packets.
We support RFC 1253, Open Shortest Path First (OSPF) MIB, August 1991. The OSPF MIB defines an
IP routing protocol that provides management information related to OSPF and is supported by Cisco
routers.
For protocol-independent features that include OSPF, see the chapter “Configuring IP Routing
Protocol-Independent Features” in this book.
To identify the hardware platform or software image information associated with a feature, use the
Feature Navigator on Cisco.com to search for information about the feature or refer to the software
release notes for a specific release. For more information, see the “Identifying Supported Platforms”
section in the “Using Cisco IOS Software” chapter in this book.

The Cisco OSPF Implementation

The Cisco implementation conforms to the OSPF Version 2 specifications detailed in the Internet
RFC 2328. The list that follows outlines key features supported in the Cisco OSPF implementation:
•Stub areas—Definition of stub areas is supported.
•Route redistribution—Routes learned via any IP routing protocol can be redistributed into any other
IP routing protocol. At the intradomain level, OSPF can import routes learned via Interior Gateway
Routing Protocol (IGRP), Routing Information Protocol (RIP), and Intermediate
System-to-Intermediate System (IS-IS). OSPF routes can also be exported into IGRP, RIP, and
IS-IS. At the interdomain level, OSPF can import routes learned via Exterior Gateway Protocol
(EGP) and Border Gateway Protocol (BGP). OSPF routes can be exported into BGP and EGP.
•Authentication—Plain text and Message Digest 5 (MD5) authentication among neighboring routers
within an area is supported.
•Routing interface parameters—Configurable parameters supported include interface output cost,
retransmission interval, interface transmit delay, router priority, router “dead” and hello intervals,
and authentication key.