Alternative custodians for congestion control in delay tolerant networks

Abstract

We approach the problem of handling storage congestion at store-and-forward (DTN) nodes by migrating stored data to neighbors. The proposed solution includes a set of algorithms to determine which messages should be migrated to which neighbors and when. It also includes an extension to the DTN custody transfer mechanism enabling a "pull" form of custody transfer where a custodian may request custody of a message from another custodian. This approach allows us to decouple the problem of storage allocation among a relatively proximal group of storage nodes from the overall problem of path selection across a larger network. Doing so admits the possibility of localized routing loops for some messages which has been shown to be desirable for avoiding some head-of-line blocking problems. We select eligible storage neighbors using a function of available storage and incident link characteristics. Using simulation, we evaluate this approach and show how migrating custodian storage in this fashion can improve message completion rate by as much as 48% for some storage-constrained DTN networks.