A delay-tolerant network architecture for challenged internets

This paper tries to address the poor performance of Internet protocols in "challenged conditions", such as those with some combination of low bandwidth, high delay, frequent down-time, long queuing delay. These causes problems due to mismatches with some of the implicit assumptions made in developing these protocols. The author propose an overlay network architecture that relies on existing links/protocols to implement a store-and-forward solution. DTN gateways control access to regions, and either bridge regions or provide a way to communicate with other nodes that are not in the same region.

This sounds very similar to an email setup. A sender sends emails to a mail gateway, which then routes it to the mail server of the receiver. Finally, the receiver pulls the email from the mail server. In this case, the DTN gateway would push the message to the receiver - isn't that what RIM does for Blackberry? Another difference, in the DTN architecture, hosts can send data directly if they are in the same region.