There's something about MRAI: Timing diversity can exponentially worsen BGP convergence

—To better support interactive applications, individual network operators are decreasing the timers that affect BGP convergence, leading to greater diversity in the timer settings across the Internet. While decreasing timers is intended to improve routing convergence, we show that, ironically, the resulting timer heterogeneity can make routing convergence substantially worse. We examine the widely-used Min Route Advertisement Interval (MRAI) timer that rate-limits update messages to reduce router overhead. We show that, while routing systems with homogeneous MRAI timers have linear convergence time, diverse MRAIs can cause exponential increases in both the number of BGP messages and the convergence time (as measured in “activations”). We prove tight upper bounds on these metrics in terms of MRAI timer diversity in general dispute-wheel-free networks and economically sensible (Gao-Rexford) settings. We also demonstrate significant impacts on the data plane: blackholes sometimes l...

• Type: Journal
• Year: 2011
• Where: INFOCOM
• Authors: Alex Fabrikant, Umar Syed, Jennifer Rexford
• Keywords: Communications, Exponential Increases, INFOCOM 2011, Routing Policies, Timer Settings