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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 32 Configuring IP Unicast Routing
Configuring OSPF
Configuring Split Horizon
Routers connected to broadcast-type IP networks and using distance-vector routing protocols normally
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 any interface from which that information
originated. This feature can optimize communication among multiple routers, especially when links are
broken.
Note In general, Cisco does not recommend disabling split horizon unless you are certain that your application
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 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).
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
no shutdown Enable the interface if necessary. By default, UNIs are disabled and
NNIs are enabled.
Step 4
ip address ip-address subnet-mask Configure the IP address and IP subnet.
Step 5
no ip split-horizon Disable split horizon on the interface.
Step 6
end Return to privileged EXEC mode.
Step 7
show ip interface interface-id Verify your entries.
Step 8
copy running-config startup-config (Optional) Save your entries in the configuration file.