You can configure split horizon and poison reverse to prevent routing loops.
Poison reverse is another method of preventing routing loops by enabling the router to advertise a route as unreachable back through the interface from which the route is learned.
Poison reverse is another method of preventing routing loops by enabling the router to advertise a route as unreachable back through the interface from which the route is learned.
If both split horizon and poison reverse are configured, only poison reverse takes effect.
interface interface-type interface-number
Enable split horizon.
Enable poison reverse.