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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter38 Configuring IP Unicast Routing Configuring OSPF

Configuring Split Horizon

Routers connected to broadcast-type IP networks and using distance-vector routing protoc ols no rm all y
use the split-horizon mechanism to reduce the possibility of routing loops. Split horizon blocks
information about routes from being advertised by a router on a ny interface from which that information
originated. This feature can optimize communication among multiple routers, especia lly wh en li nks a re
broken.
Note In general, we do not recommend disabling split hor izon u nless yo u are cert ai n th at y our a pplic a tion
requires it to properly advertise routes.
Beginning in privileged EXEC mode, follow these steps to disable split horizon on the interface:
To enable the split horizon mechanism, use the ip split-horizon interface 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 (Eth er net inte rfaces
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.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and specify the interface to
configure.
Step3 ip address ip-address subnet-mask Configure the IP address and IP subnet.
Step4 no ip split-horizon Disable split horizon on the interface.
Step5 end Return to privileged EXEC mode.
Step6 show ip interface interface-id Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.