When the Cure Is Worse Than the Disease: The Impact of Graceful IGP Operations on BGP
Network upgrade, performance optimization and traffic engineering activities often force network operators to adapt their IGP configuration. Recently, several techniques have been proposed to change an IGP configuration (e.g., link weights) in a disruption-free manner. Unfortunately, none of these techniques considers the impact of IGP changes on BGP correctness. In this paper, the authors show that known reconfiguration techniques can trigger various kinds of BGP anomalies. First, they illustrate the relevance of the problem by performing simulations on a Tier-1 network. Their simulations highlight that even a few link weight changes can produce long-lasting BGP anomalies affecting a significant part of the BGP routing table.