BGP route flapping describes the situation in which BGP systems send an excessive number of update messages to advertise network reachability information. BGP flap damping is a way to reduce the number of update messages sent between BGP peers, thereby reducing the load on these peers without adversely affecting the route convergence time.
Flap damping reduces the number of update messages by better packing the information included in the update messages. Doing this leads to some delay, or suppression, in the propagation of route information, but the result is increased network stability. You typically apply flap damping to EBGP routes (that is, to routes in different ASs). You can also apply it within a confederation, between confederation member ASs. Because routing consistency within an AS is important, do not apply flap damping to IBGP routes. (If you do, it is ignored.)
To effect BGP flap damping, you define routing policy actions by creating a named set of damping parameters and include it in a policy with the damping action (described in Table 4). For the damping policy to work, you also must enable BGP route flap damping, as described in Enable Route Flap Damping.
BGP flap damping is defined in the following RFC:
This chapter describes the following: