Configuring Split Horizon - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide
Table 3-2 Enable RIP network
Enable RIP on the specified network
Disable RIP on the specified network
Note that the operating network segment must be specified after RIP is enabled. RIP
only operates on the specified network segment. For an interface not on the specified
network segment, RIP neither receives and send routes on it nor forwards its interface
route, just as the interface does not exist. The network-address is an enabled or
disabled network address, or an IP network address on each interface.
When the command network is used for an address, the interface of the network with
this address is enabled. For example, for network 129.102.1.1, you can see network
129.102.0.0 either using display current-configuration or using display rip
command.
If RIPv1 applies, note that:
If the destination address of the current route and the address of the sending
interface do not belong to the same network (natural network segment), the route
is not sent to the neighbors if it is a supernet route. If it is a subnet route, it is sent
after being summarized.
If the destination address of the current route and the address of the sending
interface belong to the same network, the route is sent to the neighbors unless the
destination address of the route and the interface mask are unequal.
By default, RIP is disabled on all networks.

3.2.3 Configuring Split Horizon

Split horizon means that the route received via an interface will not be sent via this
interface again. It avoids the creation of routing loops to some extent. But in some
special cases, split horizon must be disabled so as to get correct advertising at the cost
of efficiency. Disabling the split horizon has no effect on the point-to-point connected
links but is applicable on the Ethernet.
Perform the following configuration in interface view.
Table 3-3 Configure split horizon
Enable split horizon
Disable split horizon
By default, split horizon of the interface is enabled.
Operation
Operation
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Chapter 3 RIP Configuration
Command
network network-address
undo network network-address
Command
rip split-horizon
undo rip split-horizon