Cisco Systems 3750E manual Configuring Ospf, No ip split-horizon, 38-25

Chapter 38 Configuring IP Unicast Routing

Configuring OSPF

Beginning in privileged EXEC mode, follow these steps to disable split horizon on the interface:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	interface interface-id	Enter interface configuration mode, and specify the interface to
		configure.
Step 3
	ip address ip-address subnet-mask	Configure the IP address and IP subnet.
Step 4
	no ip split-horizon	Disable split horizon on the interface.
Step 5
	end	Return to privileged EXEC mode.
Step 6
	show ip interface interface-id	Verify your entries.
Step 7
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To enable the split horizon mechanism, use the ip split-horizoninterface configuration command.

Configuring OSPF

This section briefly describes how to configure Open Shortest Path First (OSPF). For a complete description of the OSPF commands, see the “OSPF Commands” chapter of the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2.

Note OSPF classifies different media into broadcast, nonbroadcast, and point-to-point networks. The switch supports broadcast (Ethernet, Token Ring, and FDDI) and point-to-point networks (Ethernet interfaces configured as point-to-point links).

OSPF is an Interior Gateway Protocol (IGP) designed expressly for IP networks, supporting IP subnetting and tagging of externally derived routing information. OSPF also allows packet authentication and uses IP multicast when sending and receiving packets. The Cisco implementation supports RFC 1253, OSPF management information base (MIB).

The Cisco implementation conforms to the OSPF Version 2 specifications with these key features:

•Definition of stub areas is supported.

•Routes learned through any IP routing protocol can be redistributed into another IP routing protocol. At the intradomain level, this means that OSPF can import routes learned through EIGRP and RIP. OSPF routes can also be exported into RIP.

•Plain text and MD5 authentication among neighboring routers within an area is supported.

•Configurable routing interface parameters include interface output cost, retransmission interval, interface transmit delay, router priority, router dead and hello intervals, and authentication key.

•Virtual links are supported.

•Not-so-stubby-areas (NSSAs) per RFC 1587are supported.

OSPF typically requires coordination among many internal routers, area border routers (ABRs) connected to multiple areas, and autonomous system boundary routers (ASBRs). The minimum configuration would use all default parameter values, no authentication, and interfaces assigned to areas. If you customize your environment, you must ensure coordinated configuration of all routers.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		38-25