Damping BGP route flaps

Route Flap Damping (RFD) is anecdotally considered to be a key contributor in the stability of the Liter-Domain Routing system. It works by suppressing advertisements about persistently flapping routes, which otherwise would propagate throughout the Internet. It was recently shown that relatively stable routes, i.e., routes that fail occasionally, can be incorrectly suppressed by this mechanism for substantially long periods of time. This can be traced back to the complex interaction between BGP path exploration and the mechanism used by RFD to identify route flaps. In this paper we study the distinctive feature that distinguishes the sequence of updates following a single network event from that of persistently unstable routes. Based on this characteristic, we propose a new BGP Route Flap Damping Algorithm, RFD+, with the following properties - 1) it can correctly distinguish between route flaps and normal path exploration; 2) it suppresses routes that are frequently and persistently changing; and 3) it does not affect routes that fail occasionally. We present the algorithm and discuss its relevant properties; simulation studies are also conducted to illustrate the performance of our algorithm.