Preventing the Unnecessary Propagation of BGP Withdraws
Virginie Van den Schrieck, Pierre Francois, Cristel Pelsser and Olivier Bonaventure
Due to the way BGP paths are distributed over iBGP sessions inside an
Autonomous System (AS), a BGP withdraw that follows a failure may be propa-
gated outside the AS although other routers of the AS know a valid alternate path. This causes transient losses of connectivity and contributes to the propagation of a large number of unnecessary BGP messages. In this paper, we show, based on
RouteViews data, that a signiﬁcant number of BGP withdraws are propagated
even though alternate paths exists in another border router of the same AS. We
propose an incrementally deployable solution based on BGP communities that
allows the BGP routers of an AS to suspend the propagation of BGP withdraws
when an alternate path is available at the borders of their AS.
In Proceedings of IFIP Networking, 2009.
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