Patton electronic SmartNode 4110 Series manual Enabling RIP split-horizon processing

SmartWare Software Configuration Guide23 • RIP configuration

Mode: Interface

Step Command Purpose

1node(if-ip)[name]#ripdefault-route-valuevalue Sets the routing metric to value indicating the distance to the destination on interface name

Example: Specifying the default route metric

The following example shows how to set the routing metric to 4 on IP interface wan.

node(cfg)#context ip router node(ctx-ip)[router]#interface wan node(if-ip)[wan]#rip default-route-value 4

Enabling RIP split-horizon processing

Normally, routers that are connected to broadcast-type IP networks and that use distance-vector routing proto- cols employ the split horizon mechanism to reduce the possibility of routing loops. Split horizon blocks infor- mation about routes from being advertised by a router out of any interface from which that information originated. This behavior usually optimizes communications among multiple routers, particularly when links are broken. However, with non-broadcast networks (such as Frame Relay), situations can arise for which this behavior is less than ideal. For these situations, you might want to disable split horizon for RIP.

This procedure describes how to enable split horizon on an interface

Mode: Interface

Step Command Purpose

1node(if-ip)[name]#ripsplit-horizonEnables RIP split-horizon processing on interface name

Example: Enabling RIP split-horizon processing

The following example shows how to enable split horizon on IP interface wan.

node(cfg)#context ip router node(ctx-ip)[router]#interface wan node(if-ip)[wan]#rip split-horizon

Enabling the poison reverse algorithm

Normally, RIP uses a technique called split horizon to avoid routing loops and allow smaller update packets. This technique specifies that when the router sends a RIP update out a particular network interface, it should never include routing information acquired over that same interface.

There is a variation of the split horizon technique called poison reverse which specifies that all routes should be included in an update out a particular interface, but that the metric should be set to infinity for those routes acquired over that interface. Poison reverse updates are then sent to remove the route and place it in hold- down. One drawback is that routing update packet sizes will be increased when using poison reverse.

This procedure describes how to enable the poison reverse algorithm on an interface

RIP configuration task list 249