Re: [dtn-interest] Question

Hi, Sitaraman.  It's correct to state that DTN is based on potentially prolonged, potentially non-volatile storage at forwarding points (the original source and all routers along the end-to-end path) and on potential retransmission at all forwarding points.

But forwarding points other than the original source are features of specific topologies, not mandatory elements of the architecture.  Disruption in communication between the endpoints of a long-delay source-destination pair is handled by storage and retransmission, both at the source and also at whatever other nodes may be involved in the communication.  Intermediate nodes are not required in order to make DTN work.

For example, in the DINET experiment in 2008 we did DTN communication between nodes on Earth and a node aboard the Deep Impact flyby spacecraft in interplanetary space, 10-15 million miles away.  There were disruptions -- lapses in connectivity -- lasting several days, but DTN had no difficulty handling them despite the fact that there were no intermediate nodes between the spacecraft and the data sources and sinks on Earth.

Scott

-----Original Message-----
From: dtn-interest-bounces@irtf.org [mailto:dtn-interest-bounces@irtf.org] On Behalf Of sitaraman@nmsworks.co.in
Sent: Sunday, January 27, 2013 8:51 AM
To: dtn-interest@irtf.org
Subject: [dtn-interest] Question

Hi,
 Is it correct to state that DTN adopts a store and forward mechansim and gets around delay and disruption by having intermediate nodes retransmit on failure indication from its immediate neighbor? If this is true is it correct to state that fundamentally, the problem of disruption in long delay source-destination pair is not handled, but is solved by essentially reducing the said distance by having intermediate nodes storing and forwarding thereby acting as a "virtual" or "proxy" source and destinations?
 Thanks
Sitaraman

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