planes, trains and dtn (delay tolerant networking) ashton g. vaughs jet propulsion laboratory...

Planes, Trains and DTN(Delay Tolerant Networking)

Ashton G. VaughsJet Propulsion Laboratory

Copyright 2009 California Institute of TechnologyGovernment Sponsorship Acknowledged

Release Number: CL#09-4540

November 4-6, 2009 1AGV

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


Travel Example

LAX to DIALAX to DIA Layover#1

Layover#1 DIA to ORDDIA to ORD Layover

#2Layover

#2 ORD to JFKORD to JFK

DIADIA ORDORD

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.

PointA

PointA’

PointA’’

PointB

PointB’

PointB’’


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 NetworksTransportation Networks


Communications Network

Planet“Obstruction”

Planet“Obstruction”

Items transported:•Bits•Information

Items transported:•Bits•Information


Transmit DataTransmit Data

Communication Example

twindow opens twindow closes

Begin Transmission End Transmission

time

OWLT

OWLT

Sender Receiver

Data Arrives at Receiver

OWLT = One Way Light TimeOWLT = One Way Light Time


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 NetworksCommunications Networks


The Connection

DTN enables the representation of complex technical data with a simple and intuitive model.

DTN enables the representation of complex technical data with a simple and intuitive model.


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* List not exhaustive


Possibilities are Limitless

TitanTitan

SaturnSaturn

Earth

•DSN Stations•Titan Polar Orbiter•Saturn Moonlet Rider•Titan Submarine


Backup Slides

Planes, Trains and DTN


DTN DisconnectathonJuly 29, 30 and 31 2009

Stockholm / North America

Will Ivancic

[email protected]

216-433-3494


mailto:[email protected]

Ohio University Disconnectathon Testbed


Trinity College Dublin Disconnectathon Testbed


November 4-6, 2009 SB-16

First Look at the Deep ImpactDTN Experiment (DINET)

Scott BurleighJet Propulsion Laboratory

California Institute of Technology

Copyright 2008 California Institute of TechnologyGovernment sponsorship acknowledged.

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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.

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The DINET Stack

CCSDS TM/TC

X-band R/F

LTP retransmission

BP forwarding

CCSDS spacepackets

AMSmessaging

Remote AMScompression

Convergence layer adapter

Link service adapter

image publisher/receiver

load/go utilityfor network administration

adminprograms,rfx system,

clocks

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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.

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