IDRD: Enabling inter-domain route diversity

Abstract

In the present Internet, inter-domain routing is based on BGP-4 which does not allow for the use of multiple paths, but rather selects a single path per destination prefix. However, as the global Internet connectivity graph displays vast inherent path diversity, we believe that there is a lack of mechanisms which put this latent potential into use. To this end, we propose Inter-Domain Route Diversity (IDRD) as a mechanism which allows for diverse inter-domain paths to be propagated among carriers and used for packet forwarding. Our proposal is aimed to be efficient, backwards compatible, and incrementally deployable. In order to make use of the existing path diversity, we also propose a relaxation of the multipath route selection policy that is provably stable, while being more flexible. Our extensive evaluation of path disjointness in the Internet connectivity graph illustrates the potential benefits of IDRD. While the evaluation shows that the traditional “prefer customer” rule heavily impedes the use and propagation of the underlying diversity, it also demonstrates that our proposed relaxation of the multipath route selection policy enables near-optimal utilization of the underlying path diversity in the real Internet inter-domain topology.