Chapter 2 Advanced Routing for FortiOS 5.0 : Routing Information Protocol (RIP) : Troubleshooting RIP : Holddowns and Triggers for updates
  
Holddowns and Triggers for updates
One of the potential problems with RIP is the frequent routing table updates that are sent every time there is a change to the routing table. If your network has many RIP routers, these updates can start to slow down your network. Also if you have a particular route that has bad hardware, it might be going up and down frequently, which will generate an overload of routing table updates.
One of the most common solutions to this problem is to use holddown timers and triggers for updates. These slow down the updates that are sent out, and help prevent a potential flood.