When the Cure is Worse than the Disease: the Impact of Graceful IGP Operations on BGP

Tue, 10/30/2012 - 17:03 by Laurent Vanbever

Abstract

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 tech- niques considers the impact of IGP changes on BGP correctness.

In this paper, we show that known reconfiguration techniques can trigger various kinds of BGP anomalies. First, we illustrate the relevance of the problem by performing simulations on a Tier-1 network. Our simulations highlight that even a few link weight changes can produce long-lasting BGP anomalies affecting a significant part of the BGP routing table. Then, we study the problem of finding a reconfiguration ordering which maintains both IGP and BGP correctness. Unfortunately, we show examples in which such an ordering does not exist. Furthermore, we prove that deciding if such an ordering exists is NP-hard. Finally, we provide sufficient conditions and configuration guidelines that enable graceful operations for both IGP and BGP.

Authors
Laurent Vanbever, Stefano Vissicchio, Luca Cittadini and Olivier Bonaventure
Type
Technical Report
Source
2012.
Keywords
igp, bgp, configuration, reconfiguration, correctness, migration
Notes
http://hdl.handle.net/2078/116245
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