Title:
Network-Wide Prediction of BGP Routes
Network-Wide Prediction of BGP Routes
Authors
Feamster, Nick
Rexford, Jennifer
Rexford, Jennifer
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Abstract
This paper presents provably correct algorithms for
computing the outcome of the BGP route-selection process for
each router in a network, without simulating the complex details
of BGP message passing. The algorithms require only static
inputs that can be easily obtained from the routers: the BGP
routes learned from neighboring domains, the import policies
configured on the BGP sessions, and the internal topology. Solving
the problem would be easy if the route-selection process were
deterministic and every router received all candidate BGP routes.
However, two important features of BGP-the Multiple Exit
Discriminator (MED) attribute and route reflectors-violate these
properties. After presenting a simple route-prediction algorithm
for networks that do not use these features, we present algorithms
that capture the effects of the MED attribute and route reflectors
in isolation. Then, we explain why the interaction between these
two features precludes efficient route prediction. These two
features also create difficulties for the operation of BGP itself,
leading us to suggest improvements to BGP that achieve the
same goals as MED and route reflection without introducing the
negative side effects.
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Date Issued
2006
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Technical Report