Abstract:

Routing policies are used to implement traffic agreements in BGP
routed networks, and may give rise to a configuration where the
policies are in dispute in a way such that no agreement is met for a
stable routing state.  To remedy routing divergence due to policy
disputes, two different kinds of solutions have been proposed, namely
static solutions and dynamic solutions.  As a dynamic solution,
Griffin and Wilfong have suggested an extension of the path-vector
routing algorithm used in BGP, in which route histories are maintained
in disseminated routes.  If routing divergence arise due to policy
disputes, the history will eventually contain cyclic patterns of
entries, which can be detected by the routers.  Preliminary results by
Nykvist and Motyckova suggest that the proposed mechanism fails to
indicate oscillation due to policy disputes under certain conditions.