DTND is for Delay (Deep Space)
D is for Disruption (Military)D is for Disconnected (All)
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DTN in a nutshellDTN Source
DTN Bundle Forwarding Agent
DTN Destination
Where are you
headed?
Knoxville, Wheeling, then
Fort Pitt.
Can you take this letter to my Brother
at Fort Pitt?
Yes Mam, I sure can.
Dave Smith@ Ft. Pitt
Dave Smith@ Ft. Pitt
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DTN in a nutshellDTN Bundle
Forwarding Agent
Dave Smith@ Ft. Pitt
DTN Bundle Forwarding Agent
DTN Destination
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Why DTN? Cons
Non-Optimal Solution for particular situations such as if limited infrastructure exists
Adds Overhead Can be significant
overhead depending on the packet size
Pros Flexibility Reliability Robustness
DTN is a network overlay abstraction. • This requires overhead.• One is either willing to trade overhead for flexibility or they are not.
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Delay/Disruption Tolerant Network (DTN)
A standardized store and forward protocol and routing protocol
Designed for extreme environments Large transmission link delays Extended periods of network partitioning Routing capable of operating efficiently in the following
environments Frequently-disconnected Pre-scheduled Opportunistic link availability High per-link error rates making end-to-end reliability difficult Heterogeneous underlying network technologies (including non-
IP-based internets) The architecture operates as an overlay network
Institutes a new naming architecture based on Uniform Resource Identifier (URI)
Concept of Late Binding of Name to Address
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DTN Environments
Sched
uled
(long dela
y)
Opportunistic(Intermittent Connectivity, Short Delay)
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Known problems with DTN bundling IRTF DTN Research Group adopted bundling as ‘universal’ way to
deal with DTNs. Currently not investigating alternatives. Bundling is not mature by any stretch of the imagination
Security, routing, naming, reactive fragmentation, key and policy management, etc. are still open issues.
Network overlays inherit all the good and bad of the underlying networks. Example, if one does not have a good handle of how to secure an ad hoc
network, running DTN over an ad hoc network implies one has to address both the ad hoc and the DTN issues (routing, quality of service, security, etc...)
The current bundle design has no built-in reliability checks. Security protocols are emphasized. Reliability is currently (as of November 2008) being retrofitted as an add-on to security. [Fixable]
The current bundling protocol (RFC 5050) assumes all nodes know current UTC thus requiring network synchronization. [Fixable]
Bundling is really still a research effort!
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Palm Island Resort, Dubai, 14 Dec 2003 (UK-DMC)
www.dmcii.com
The Cape of Good Hope and False Bay. False colours – red is vegetation. Taken by UK-DMC satellite on the morning of Wednesday, 27 August 2008. Downloaded using bundling over Saratoga, with proactive fragmentation. Fragments assembled at NASA Glenn, then post processed at SSTL.First sensor imagery delivered by bundles from space.
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Home Agent
VMOC
Open Internet
VMOCDatabase
SatelliteScheduler
& Controller
Ground Station 3
Ground Station 2Ground
Station 1
->> Time ->>
Large File TransferOver Multiple Ground Stations- DTN is a Potential Solution -
DTN Bundle AgentIntermediary
DTN Bundle AgentIntermediary
DTN Bundle AgentIntermediary
DTN Bundle AgentSink
Scenarios Deep Space Mars Relay Simple Sensor Networks Data Mule Rapid Disruption (Fades due to RF) Low Earth Orbiting Sensor Satellite Geostationary Bent Pipe Relay Satellite Unmanned Aeronautical Vehicles
Mars Relay Mars Odyssey Spacecraft +-------+ _ +-------+ | |:_:| | Deep Space Link +-------+ +-------+ _,,..--''' . . ___..---'' `. Proximity -.._ `. `. Link `- /\''' `. _,,. /__\ `,-' Deep ,'.------. Space `. / | Mars | Network `. | | Expl.| | | Rover| | `------'
Odyssey Relay Operations
Long DelayShort Delay
DTN Bundle Agent
DTN Bundle Agent
DTN Bundle Agent
UAV via GEO Satellite
DTNBundle Agent
DTNBundle Agent
DTNBundle Agent
RF RelayDTN
Bundle Agent
.-------. |Bundle | .-------. |Agent 1| |Bundle | .--o `-------' /''\. |Agent 5| / `. `. .' '._ .-----.,--. `-------' / | \ | `.._|Data | ``. \ / `. / |Mule | `-. \ ' |_ | `-----' `. ,/ | | Movement \.,.--- | ' <<======= | / | / | | Path Well .-------. | | Traveled |Bundle | | | |Agent 3| | / ...._ `-------' \ | | `. / `\ \ _.. | `./ .' `' `---`... `.._ `-. ,' .-------. _, ". ``. \ _,,' |Bundle |,' `. \ `--...,-'. |Agent 2| `. `. | `-------' `. _ \ .-------. ' `'-...._ | |Bundle | `"--------' |Agent 4|
Data Mule
LEO Sensor Satellite +-------+ _ +-------+ | |:_:| | +-------+ +-------+ ,' `. Space/Ground ,' `-. Space/Ground Link 1 ,-' `. Link 2 ,' `._ ,' `. ,' Connect Connect `._ _,' T1 T2 `. . ' ` / Ground `. ..,' Ground Station /\'' ___...------'''''''------....__ /\ Station 1 /__\.,--' `'--./__\ 2 _,,-' ._ _, `--.._ ' `. Ground/Ground Ground/Ground ,' ' `-. Link 1 Link 2 ,-' `._ ,-' `. _,' ' .-----------. | Data | |Collection | | Center | `-----------'
Low Earth Orbiting Satellite
Network Management Monitoring and Measurement
Debugging and Troubleshooting Performance profiles -- delay and throughput; disruption
and connectivity Configuration
Routing Security configurations (and policy) DTN-Tables ? (long term)
Applications (related to traffic generation for testing and monitoring purposes) General User Applications that can be use to test, stress
and exercise the network (i.e. DTNtraceroute, DTNsend/receive, DTNperf, etc...)
DTN useful applications (i.e DTNdatabase synchronization (DTNrsync), DTNmail, DTNchat ?, etc...)
Network ManagementMonitoring and Configuration General Requirements
Local Network Management Remote Network Management
Monitoring Bundle Processing System Characteristics
Convergence Layers Multi-Homing Radios Processing Power Onboard Storage
Configuration Routing Name Resolution Local and Network Time Security
Definitions Local Management ≡ Logged into the device
locally or via Real-time access such as via a connected IP network Assume high bandwidth, no disruption and
insignificant delay Remote Management ≡ Managed over a
DTN network Handles Long Delays, Long Periods of Disruption,
and Low Bandwidths
General Requirements Management and Configuration should work for all DTN
environments High delay, long periods of disconnection, low bandwidth System may be multiple hops away and never reachable in a
single hop System may not be synchronized
(although current bundling RFC 5050 assumes synchronization) Multiple security levels
Secure Login and encrypted data transfer (i.e. SSH or TLS for local management, something yet to be defined for remote management)
Monitoring - Modest Security Configuration - High Security
Remote Management uses bundling Remote Configuration
Incremental Test, Validation, restore/recovery
Utilities – beginnings of NetMgt(Make utilities interoperable between ION and DTN-2) DTN-ping DTN-send/receive DTN-traceroute DTN-perf DTN-heartbeat DTN-email DTN-chat Bundle Count / Traffic Measurement (NEW Request)
NASA DEN Phase-0 Scenario
Phase-0Continuous ConnectivityStatic routingNo BP Security
Delay: Lunar 3 secBW: 128kbps [>100Mbps]BP/LTP/Encap orBP/LTP/IP/Encap
Delay: 100s msec?BW: 72/k/192k
StoryEVA sending some sort of telemetry (different kinds to APL and JPL)Understand that EVA data wouldn’t really go to APL/JPL
BP/LTP/Encap or BP/LTP/IP/Encap?OhioU has TCPCL for ION?
BW: 10Mbps
Limit the amount of available storage (later)
DTNBone We invite you to participate in the DTNbone
Web Page http://www.dtnrg.org/wiki/DtnBone Mail list http://korgano.eecs.ohiou.edu/mailman/listinfo/dtnbone
Establish a worldwide collection of nodes running DTN bundle agents and applications. Remote management and control of nodes, Interoperability, Application deployment and testing, Operations across administrative boundaries.
DTNGW
Rover
Habitat
ScienceSensor
1 Mbps
256 kbps
128 kbpsEARTH
MOON
L2Relay
LunarRelay
Always ON ?
Intermittent
Multiple Switched Ground Stations emulated as one single DTN GW
InternationalPartner #2
InternationalPartner #1
Switched
DTNGW
L2Relay
Habitat
LunarRelay
Rover
Sensor
SW
SW
CS
CS
CS
CS
Real-time Control PlanDefined as part of Local Management
CS Channel Simulator(Rate, BER and Connectivity)
DTN Data Flow