Triggered updates
Normally, each sends RIP - router in a fixed time interval (by default every 30 seconds) all his known route information to its neighboring routers. If the Triggered Updates option is enabled , it also sends them whenever the metric changes for one of the routes it manages . This can be done, for example, by an update that he received from one of his neighbors.
Like Split Horizon, triggered updates are a mechanism by which routing loops are to be avoided, which in RIP can lead to the so-called count-to-infinity - the rapid forwarding of new route information is intended to prevent outdated route information from circulating in the network for too long.