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# November 4-6, 20091AGV

Transportation Networks LAX DIA ORD JFK Los Angeles Norwalk Anaheim San Juan C. San Diego BEGIN END Transfer Items transported: People Freight Items transported: People Freight November 4-6, 20092AGV

Travel Example LAX to DIA Layover #1 Layover #1 DIA to ORD Layover #2 Layover #2 ORD to JFK DIA ORD The Traveler remains in the custody of DIA and ORD airports during Layovers. The Traveler remains in the custody of DIA and ORD airports during Layovers. Point A Point A’ Point A’’ Point B Point B’ Point B’’ November 4-6, 20093AGV

Relevant Travel Issues Time Tables – Starting Location (A) – Departure Time – Arrival Time – Ending Location (B) Derived Information – Transit Time (Trip Duration) – Layover Time – Distance remaining to Final Destination Transportation Networks November 4-6, 20094AGV

Communications Network Planet “Obstruction” Planet “Obstruction” Items transported: Bits Information Items transported: Bits Information November 4-6, 20095AGV

Transmit Data Communication Example t window opens t window closes Begin TransmissionEnd Transmission time OWLT SenderReceiver Data Arrives at Receiver OWLT = One Way Light Time November 4-6, 20096AGV

Relevant Travel Issues Time Tables – Sender Location (A) – One Way Light Time – Transmission Window Duration – Receiver Location (B) Derived Information – Transmission Duration – Custody Duration – Distance remaining to Final Destination Communications Networks November 4-6, 20097AGV

The Connection DTN enables the representation of complex technical data with a simple and intuitive model. November 4-6, 20098AGV

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, 20099AGV

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

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

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

DTN Disconnectathon July 29, 30 and Stockholm / North America Will Ivancic November 4-6, AGV

Ohio University Disconnectathon Testbed November 4-6, AGV

Trinity College Dublin Disconnectathon Testbed November 4-6, AGV

November 4-6, 2009 SB-16 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. AGV

November 4-6, 2009 SB-17 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. AGV

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

November 4-6, 2009 SB-19 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 VxWorks, 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. AGV