A flapping route is an unstable route that is advertised and withdrawn over and over again. Every time a flap occurs, a BGP UPDATE message is sent. When routers have to process many BGP UPDATE messages, their CPU load increases.
BGP route dampening can be used to prevent installing flapping BGP routes and forwarding them to other BGP routers. This decreases the CPU load of routers and increases network stability. Nowadays, routers are powerful enough to process BGP updates so dampening isn’t considered a best practice anymore
RFP has 5 attributes - the default values are shown
When the route exceeds the suppress limit, the route is dampened.Once the route is dampened, the router won’t install the route in the routing table nor advertise it to other BGP neighbor.
If for example the penalty is 4000 and the half-life time is 15 minutes. After 15 minutes the penalty will be 2000, after another 15 minutes, the penalty is 1000, and after another 15 minute, the penalty is 500. Once the penalty is below the reuse limit of 750, the route can be used again and advertised to other BGP routers. When the penalty is below 50% of the reuse limit, the penalty is removed from the route.
The maximum suppress limit ensures that a route won’t be dampened forever. The maximum suppress time is 3600 secs or 60 minutes by default.