Delay Tolerant Networking Birds of a Feather 1300-1700, 4 October 2007 Heppenheim, Germany.

Delay TolerantDelay TolerantNetworkingNetworking

Delay Tolerant NetworkingBirds of a Feather

1300-1700, 4 October 2007

Heppenheim, Germany

4 October, 2007 CCSDS DTN BoF -- Heppenheim 2

Original AgendaTime Topic Presenter

1300-1400 Possible space mission drivers for DTN technology:MERsESAOthers?

1400-1500 Current state of the IRTF DTN Protocol. How good a fit is it for CCSDS?

Documents (Arch, Protocol Spec)DTN2IONProtocol overheadDocumentsSecurity

Keith Scott, Scott Burleigh

1500-1510 Solicitation of interest: do we think CCSDS should invest in standardizing DTN technology and protocol(s)?

Poll for agency support

1510-1600 Assuming interest, how to incorporate DTN into CCSDS (adopt, adapt [issues?], …)?

Discussion

1600-1700 Draft DTN WG Charter DiscussionsAgency support (resources)Schedule (1 year?)

How to specify?2 implementation req’t?s

Discussion


Proposed AgendaPartial Order

Topic

First DTN Overview– DTN as a formalization of long-term store-and-forward relay

technologies– Overlay network on top of [transport | network | link]– DTN as a refactorization and generalization of CFDP with additional

capabilities– Relationship to Mars Interoperability WG

Second Current state of DTN Protocol and Implementations– Specifications (Architecture, Protocol, Security)– DTN2 Reference Implementation– Interplanetary Overlay Network (ION)

Architectures and interoperability pointsDTN activities

Last DTN WG Charter Discussions (assumes interest in WG formation)– Agency support (resources)– How to incorporate DTN into CCSDS (adopt, adapt [issues?], …)?– Schedule?


DTN in a Nutshell“Postal model” of Communications

Store and Forward, minimal interactivity

source

destination

Persistent Storage

Routing

Disrupted Region

DTN provides network services across disruption and massive differences in delay and bandwidth

DTN provides network services across disruption and massive differences in delay and bandwidth

Link Decoupling


DTN Overlay Network

• DTN interconnects disparate networking regions– Operates above regional transport layer stacks– Allows flexibility to adapt to specific environments

Application

DTN

Transport

Network

Link

Phy

DTN

Transport

Network

Link

Phy

Network

Link

Phy

Terrestrial NetworkPlanetary-local Network

Transport

Network

Link

Phy

Application

DTN

Transport

Network

Link

Phy

DTNGateway

Deep Space

DTN

Transport

Network

Link

Phy

Transport

Network

Link

Phy

DTNGateway

persistent storage


DTN Overlay Network for Deep Space (No Relays Yet)

• For space, DTN can run over CCSDS protocols– Could also run directly over space packets, e.g.

CFDP / AMS

DTN

Transport

Network

Link

Phy

DTN

Transport

Network

Link

Phy

Network

Link

Phy


LTPPktsAOS

CFDP / AMS

DTN

TCP

IP

Link

Phy

DTNGateway

Deep Space

DTN

LTPPktsAOS

TCP

IP

Link

Phy

DTNGateway

persistent storage


LTPPktsAOS

LTPPktsAOS

DTN Accounting: Custody Transfer

• DTN reliability is via custody transfer– Once custody has been accepted by a downstream

bundle, the current custodian is safe to remove it

CFDP / AMS

DTN

Transport

Network

Link

Phy

DTN

Transport

Network

Link

Phy

Network

Link

Phy


CFDP / AMS

DTN

TCP

IP

Link

Phy

DTNGateway

Deep Space

DTN

TCP

IP

Link

Phy

DTNGateway

persistent storageCustody Transfers


LTPPktsAOS

LTPPktsAOS

DTN Accounting: Status Reports

• DTN provides a number of status reports for accountability from intermediate nodes– Time of (receipt, custody, forwarding, deletion)– Settable on a per-bundle basis

CFDP / AMS

DTN

Transport

Network

Link

Phy

DTN

Transport

Network

Link

Phy

Network

Link

Phy


CFDP / AMS

DTN

TCP

IP

Link

Phy

DTNGateway

Deep Space

DTN

TCP

IP

Link

Phy

DTNGateway

persistent storageBundle status reports from intermediate nodes


LTPPktsAOS

LTPPktsAOS

DTN Accounting: Delivery Report

• One of the status reports is a delivery receipt, indicating the the bundle has been delivered to the destination application

CFDP / AMS

DTN

Transport

Network

Link

Phy

DTN

Transport

Network

Link

Phy

Network

Link

Phy


CFDP / AMS

DTN

TCP

IP

Link

Phy

DTNGateway

Deep Space

DTN

TCP

IP

Link

Phy

DTNGateway

persistent storageEnd-to-End Delivery Receipt


DTN’s Derived Design Rules• Don’t plow the same ground twice – hold the gains

you’ve achieved

• Don’t engage in unnecessary chit-chat – build complete transactions and make network accesses count

• Don’t depend on information from inaccessible / remote places if you can avoid it – build a sequence of local control operations and use late binding

• Don’t force homogeneity – allow different network components to use environmentally-relevant optimizations


Cerf Cuberover1.marslan

Cerf Cuberover2.marslan

Motes

lander1.mars

Cerf Cube

orbiter2.marsorbiter1.mars

LaptopLaptop

orbiter1.ipn orbiter2.ipn

gs1.ipn

Laptop

gs1.internet

pi.internet

Laptop

Earth’sI nternet

DeepSpaceBackbone

MarsI n-situI nternet

Bundle

CFDP

Bundle

CFDP

Bundle

BundleBundle

CFDP

Bundle

CFDP

lander1.marslan

MarsRelayNetwork

MarsSensorWeb

Circa 2002 Demonstration


Relationship to Mars Interoperability Working Group

• Mars Interop. WG standardizes the parameters and options for the various data links, concentrating on the relay orbiter-to-remote surface interface– Reliability, accounting, file transfer left to upper layers– DTN can provide these


Space Relay Requirements

• Support for automated multi-hop data relay between remote elements and Earth– Short local control loops enable finer-grained decision

making and better performance– Cross-support between different agencies’ assets

• CCSDS-wide naming / addressing scheme to allow unified and unambiguous identification of communications endpoints– Supports cross-support between different agencies’

assets– Something for SANA to manage


Why DTN?• Capabilities:

– Reliable delivery via custody transfer– Built-in accounting mechanisms (time of receipt, time of forward, …)– Precedence– Extensibility– Security that protects the infrastructure

• DTN Provides more than CFDP alone– Additional per-hop accounting plus end-to-end delivery notifications– DTN supports fragmentation and delivery over multiple parallel paths– Security

• Cleanly extend terrestrial endpoint past end of space data link (cross-support of IP on the ground would make this cross-supportable)

• Generalization (refactoring) of CFDP capabilities to provide both message and file paradigms


Current State of DTN• Delay Tolerant Networking is being developed under the Internet Research

Task Force– Architecture document: RFC4838– Bundle Protocol Specification: In process to be published as an informational

RFC• Optional reliability via custody transfer• End-to-end and hop-by-hop security mechanisms

– Security• Draft-irtf-dtnrg-sec-overview-03• Draft-irtf-dtnrg-bundle-security-04

– Bundle Authentication– Payload Security– Payload Encryption

• Implementations– DTN2 reference implementation (available from dtnrg.org)– JPL Interplanetary Overlay Network (ION) implementation– TKK implementation for Symbian cellphone– Georgia Tech .Net implementation


Interoperability at IETF67

TKK DTN2 MITRE* BBN* GA Tech ION

Language C++ C++ C++ C++, Java C# C

PlatformSymbian cellphone

MacOs and Linux on PC and Nokia 770

Linux on PC;

external router

Linux on PC;

external CL adapter

.NET on Win32 & Linux on

PC & PDA

Linux on PC

Custody Transfer Status

Reports

TCP CL UDP CL

* Derived from DTN2 RI

November 5-10, 2006


Topology for IETF67 Interoperability Tests

Demmer-mac.11, RI

BBN, java.31, RI ext CL

Demmer-pc.12

Pocket, C#.63

jpl1.23, ION

mitre2.52, RI

War, C#.61

770.42, RI on Nokia770

mitre.51, RI ext Rtr

9300, C++.41, Symbian

tcp

tcp

udp

udp

udp udp

tcp

Status reports direct to demmer-macDestination dtn://9300.dtn/send

udp

udp

Charon, C#.62, GA Tech

“Hey, these status reports are kinda useful.”

udp


Features Tested at IETF67

• End-to-end transmission – With and without custody transfer– Moving between convergence layers

• Payload sizes varying from 6 to 1545 bytes– Raw text messages– Email-format messages destined for Symbian phone

• All status reports generated and parsed– Report-to different from source endpoint

• Partial test of TTL expiration


Bundle Protocol Headers (Blocks)

Creation Stamp1

Version Flags

Blocklength

DestinationScheme

DestinationSSP

SourceScheme

SourceSSP

Report-toScheme

Report-toSSP

Custodianscheme

CustodianSSP

CreationStamp2 Lifetime

DictionaryLength

Dictionary(Variable)

FragmentOffset

TotalADU length

Bundle Protocol Headers

BlockType

Primary BundleBlock

ControlFlags

Block Length

Payload

Bundle PayloadBlock

32 bits

CBHE Compressed Bundle Header Encoding

Creation Stamp1

Version Flags

Blocklength

SchemeNumber

DestinationElement #

DestinationService #

SourceElement #

SourceService #

Report-toElement #

Report-toService #

CustodianElement #

CreationStamp2 Lifetime

FragmentOffset

TotalADU length

BlockType

Primary BundleBlock

ControlFlags

Block Length

Payload

Bundle PayloadBlock

DictionaryLength=0

32 bits

Dictionary allows references to address information that may occur multiple times (e.g. src. and dst. schemes the same; src and report-to endpoints the same).

Dashed boxes are SDNVs.


DTN Activities

• NASA effort to demonstrate flight-ready DTN by 2010– Target of TRL 8 by 2010

• Active research community– Testing the protocol– Maintaining multiple interoperable implementations– Developing additional capabilities

• ‘Space-Oriented’ Implementation and Applications– ION Implementation– Remote AMS over DTN


How DTN Might Fit Within CCSDS: Architectures and Interoperability

• Slides with strawman architectures and interoperability points


DTN DTN

SpacePkts

Strawman DTN ArchitectureDownlink

RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

GroundStation

ControlCenter

DTN

AOSX-SupportXfer Svcs AOS Ether

IP

TCP

Application Application

TerrestrialX-Support 1

Deep-SpaceX-Support

RelayX-Support

Agency A Agency B Agency C Agency A

SpacePackets

SpacePkts

SpacePkts

• Minimal DTN deployment• No additional interoperability

requirements beyond current plans



RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

DTN

GroundStation

ControlCenter

DTN


IP

TCP



Deep-SpaceX-Support

RelayX-Support


SpacePackets

SpacePkts

SpacePkts

• DTN in relay orbiter• Significant performance increase


DTN


RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

DTN

GroundStation

DTN

ControlCenter

DTN

Terr.User


IP

TCP

Ether

IP

TCP



Deep-SpaceX-Support

RelayX-Support

Agency A Agency B Agency C Agency D Agency A

SpacePackets

SpacePkts

SpacePkts

SpacePkts


• Fully deployed DTN• Additional terrestrial interoperability

shown


DTN DTN

SpacePkts

Strawman DTN ArchitectureUplink

RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

GroundStation

ControlCenter

DTN

TCX-SupportXfer Svcs

TCCLTUs

Ether

IP

TCP



Deep-SpaceX-Support

RelayX-Support


SpacePackets

SpacePkts

SpacePkts

• Minimal DTN over TC deployment• No additional interoperability

requirements beyond current plans



RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

DTN

GroundStation

ControlCenter

DTN


TCCLTUs

Ether

IP

TCP



Deep-SpaceX-Support

RelayX-Support


SpacePackets

SpacePkts

SpacePkts

• DTN at remote relay


DTN


RemoteElement

Prox-1

DTN

RemoteRelay

Prox-1

DTN

GroundStation

DTN

ControlCenter

DTN

Terr.User


TCCLTUs

Ether

IP

TCP

Ether

IP

TCP



Deep-SpaceX-Support

RelayX-Support

Agency A Agency B Agency C Agency D Agency A

SpacePackets

SpacePkts

SpacePkts

SpacePkts


• Fully deployed DTN• Additional terrestrial interoperability

shown• DTN boundaries can be security

boundaries; control center checking


Conclusions• Orbiter-Landed element interoperability is necessary but

additional features are needed– Packets by themselves don’t provide reliability, mutli-packet

ADU, or accountability– CFDP provides many but not all of these features under a ‘file-

specific’ model

• DTN generalizes CFDP functionality by refactoring it into its constituent parts (LTP, DTN, Application) and adds additional capabilities– More useful for SMC?

• CCSDS can leverage work done by the DTN community– Demonstrated interoperability– Protocol extensions


Draft WG Deliverables (From Group Discussion)

• DTN Green Book– Architecture

• Compatibility w/ existing systems

– Relationship between DTN and CFDP– Ops concepts

• JAXA conops (source apps and time) – data recorder design

– Mission Scenarios– Section on routing requirements / ideas or separate document

on routing requirement s / ideas (no protocol book)

• DTN bundle protocol (Blue Book)• LTP protocol (Blue Book)

Delay Tolerant Networking Birds of a Feather 1300-1700, 4 October 2007 Heppenheim, Germany.

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Transcript of Delay Tolerant Networking Birds of a Feather 1300-1700, 4 October 2007 Heppenheim, Germany.