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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
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Chapter 40 Configuring IP Unicast Routing
Configuring RIP
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, we do 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.
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.