Planes Trains and DTN Delay Tolerant Networking Ashton

Planes, Trains and DTN (Delay Tolerant Networking) Ashton G. Vaughs Jet Propulsion Laboratory Copyright 2009 California Institute of Technology Government Sponsorship Acknowledged Release Number: CL#09 -4540 November 4 -6, 2009 AGV 1

Transportation Networks ORD Los Angeles DIA JFK Norwalk Anaheim LAX San Juan C. BEGIN Transfer San Diego Items transported: • People • Freight END November 4 -6, 2009 AGV 2

Travel Example Point A Point B LAX to DIA Point A’ Layover #1 Point B’ DIA to ORD DIA Point A’’ Layover #2 Point B’’ ORD to JFK ORD The Traveler remains in the custody of DIA and ORD airports during Layovers. November 4 -6, 2009 AGV 3

Relevant Travel Issues • Time Tables Transportation Networks – Starting Location (A) – Departure Time – Arrival Time – Ending Location (B) • Derived Information – Transit Time (Trip Duration) – Layover Time – Distance remaining to Final Destination November 4 -6, 2009 AGV 4

Communications Network Planet “Obstruction” Items transported: • Bits • Information November 4 -6, 2009 AGV 5

Communication Example Data Arrives at Receiver OWLT Sender Receiver Transmit Data OWLT Begin Transmission End Transmission time twindow opens twindow closes OWLT = One Way Light Time November 4 -6, 2009 AGV 6

Relevant Travel Issues • Time Tables Communications Networks – Sender Location (A) – One Way Light Time – Transmission Window Duration – Receiver Location (B) • Derived Information – Transmission Duration – Custody Duration – Distance remaining to Final Destination November 4 -6, 2009 AGV 7

The Connection DTN enables the representation of complex technical data with a simple and intuitive model. November 4 -6, 2009 AGV 8

DTN • Store and Forward system – Layovers are analogous to Store (data remains in custody of the node) – Travel Time is analogous to Forwarding • Multiple Transport Mechanisms – Planes, Trains and Buses – TCP, UDP, IP, R/F and LTP protocols* • Flexible – Mesh – Tree – Star • Efficient and Light Weight – Desktop Computers: DTN Disconnectathon – Spacecraft Computers: DINET • Extensible – AMS – RAMS – CFDP * List not exhaustive November 4 -6, 2009 AGV 9

Possibilities are Limitless Earth • DSN Stations • Titan Polar Orbiter • Saturn Moonlet Rider • Titan Submarine Titan Saturn November 4 -6, 2009 AGV 10

Possibilities are Limitless Earth • DSN Stations • Titan Polar Orbiter • Saturn Moonlet Rider • Titan Submarine Titan Saturn November 4 -6, 2009 AGV 11

Backup Slides Planes, Trains and DTN November 4 -6, 2009 AGV 12

DTN Disconnectathon July 29, 30 and 31 2009 Stockholm / North America Will Ivancic william. d. ivancic@nasa. gov 216 -433 -3494 November 4 -6, 2009 AGV 13

Ohio University Disconnectathon Testbed November 4 -6, 2009 AGV 14

Trinity College Dublin Disconnectathon Testbed November 4 -6, 2009 AGV 15

First Look at the Deep Impact DTN Experiment (DINET) Scott Burleigh Jet Propulsion Laboratory California Institute of Technology Copyright 2008 California Institute of Technology Government sponsorship acknowledged. November 4 -6, 2009 AGV SB-16

DINET Summary • • The purpose of the DINET project is to demonstrate NASA’s implementation of the IRTF-conformant open Delay-Tolerant Networking protocols (Interplanetary Overlay Network – “ION”) in flight and ground software functioning at Technology Readiness Level 7 or 8, making it ready for use by space flight projects. Plan: – Upload ION software to the Deep Impact “flyby” spacecraft during inactive cruise period, while the spacecraft is en route to encounter comet Hartley 2. – Use the DI (now “EPOXI”) spacecraft as a DTN router for image bundles flowing from one lab machine to another, over interplanetary links. – Use the Deep Space Network tracking stations: eight tracking passes of 4 hours each, separated by intervals of 2 to 5 days. Uplink at 250 bytes/sec, downlink at either 110 or 20, 000 bytes/sec. – On the last four passes, induce data loss by randomly discarding 1/32 of all received packets, thus forcing the exercise of LTP retransmission. – One-way signal propagation delay is initially 81 seconds, drops to 49 seconds by the end of the four-week exercise. – Use AMS publish/subscribe over BP/LTP to send about 300 small images through this network, via the spacecraft. Track statistics, display on reception. November 4 -6, 2009 AGV SB-17

The DINET Stack image publisher/receiver AMS messaging load/go utility for network administration Remote AMS compression BP forwarding Convergence layer adapter LTP retransmission Link service adapter admin programs, rfx system, clocks CCSDS space packets CCSDS TM/TC X-band R/F November 4 -6, 2009 AGV SB-18

Key Findings • The protocols work well. – Signal propagation delays of 49 to 89 seconds were tolerated. – End-to-end latencies on the order of days were tolerated. – Station handovers and transient failures in DSN uplink service were handled automatically and invisibly. – Protocol overhead was minimal. – Dynamic route computation was generally successful. • The software is highly stable. – No software failures in four weeks of continuous operation on Vx. Works, Solaris, and Linux platforms. – No effect on the operation of other flight software. – No leakage of memory or non-volatile storage space. • Clock synchronization and OWLT estimation errors of several seconds had no noticeable effect on network operation. November 4 -6, 2009 AGV SB-19