The big difference between BP and IP is that, while IP assumes a more or less smooth pathway for packets going from start to end point, BP allows for disconnections, glitches and other problems you see commonly in deep space, Younes said. Basically, a BP network — the one that will the Interplanetary Internet possible — moves data packets in bursts from node to node, so that it can check when the next node is available or up.

via Vint Cerf and NASA’s BP and DTN Protocol: How It Works.

DTN = Disruption Tolerant Networking