The Interplanetary InternetChallenges for the Internet's Evolution

TERENA Networking Conference 200024 May 2000

Scott Burleigh, Vint CerfBob Durst, Adrian Hooke

Keith Scott, Eric Travis, Howard Weiss

A Candidate Sharing of Issues and A Candidate Sharing of Issues and TechnologiesTechnologies

• Generally high bandwidth-delay products• Possible data loss due to bit-errors and/or

transient link outages• Potentially asymmetric data rates

Satellite,Wireless

Surfaceto Orbit

Relay

• Power constrained end systems• Episodic/disjoint connectivity• Networks may need to be self-organizing

SurfaceOperations

• Ultra high bandwidth-delay product• typically >> transaction size

• ‘Ping-pong of bursts’ replaces streaming

Internetbackbone

LongHaul to

Earth

• Channels often periodically unidirectional• Need for progressive/selectable reliability• Need for store-and-forward delivery

Mobile/Rovingapplications

Mars

MoonEarth

The Basic IPN Concept:Construct a “Network of internets”Deploy standard internets in low latency remote environments (e.g., on or around remote rocks)

Connect distributed internets via an interplanetary backbone that handles the high latency deep space environment.

Create gateways and relays to interface between low and high latency environments

i

I Wired

Tetherless

DeployedInternets

StableBackbone

Security

InterplanetaryGateways

Inter-InternetDialog and Nodes

IPN Technology Thrust Areas earth.sol

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The Good News Is ...Much of the ongoing work in terrestrial mobile ad hoc networking is interesting, relevant, and timely

We can probably apply these emerging terrestrial technologies to our in-situ space communications needs, rather than developing them from scratch

But…Anything deployed on remote rocks is going to be slow to evolve

What’s a Backbone?A set of high-capacity, high-availability links between network traffic hubs

Terrestrial backbone links are between hubs like Lisbon and Paris.

Interplanetary backbone links are between hubs like Europa and Mars.

Availability is a matter of perspective...

DeployedInternets

StableBackbone

Security

InterplanetaryGateways

Inter-Internet Dialogand Nodes

Differences Between Terrestrial and Interplanetary Backbones

TerrestrialBackbone

InterplanetaryBackbone

< .1 10 to 10,000

Wired Untethered, moving

Copper, glass Space

“low” Very high

“low” High (power is costly)

Delay (light sec)

Connectivity

Medium

Deployment $

Operations $

Repair, upgrade $ “low” Very high

On the Interplanetary Backbone:Communications capacity is expensive

Bits count

Round Trips hurt

Interactive protocols don’t workInternet protocol suite doesn’t scale well with increasing latency Negotiation is impracticalReliable in-order delivery takes too longProtocols need to be connectionlessCongestion control and flow control are difficultReliance on forward coding versus retransmission for error recovery

Custody, store-and-forward data transfer is fundamental

“Chatty Telephony” gives way to “Bundled Mail” as the model of operations

Communication in a Micro-Power Environment:

It's a Full-Stack JobLink Layer:

• Effects of very low SNRs in conjunction with QOS Multiple simultaneous coding schemes needed?Resource reservation/interference avoidance

• Signaling of link status to upper layers: availability; capacity and congestion status; error status

Network Layer:

• MANETs with both fast- and slow-moving elements• Changing resource availability• Synthesis and propagation of link status• Resource allocation: integrated services?, adaptive• Self organization

Communicating in a Micro-Power Environment:

It's a Full-Stack JobTransport Layer:

• Power-efficiency requires careful balance between link layer coding and transport layer retransmission• Adaptive to changing network conditions

QOS-responsiveTolerant of link outages and mixed losses

Application Layer:

• Service location in infrastructure-free environment• Efficient network management and control• Health and status of mobile nodes (not just networking aspects)

While communications with distant rocks can be exciting...

The IPN is really about exploring the evolutionary paths the Internet may take as the dynamic range of interconnected environments continues to increase...• Autonomy - functional and/or administrative• Mobility - not just nodes, but entire networks• Impedance Matching - keeping the backbone fair, but

allowing subnets to be aggressive

While preserve the end-to-end semantics of communications

Bundle Space

Bundle space supports end-to-end transfer across IPN domains and/or

heterogeneous network protocol stacks

Bundle

Transport

Application

Transport

Network Network

Transport

Application

Network

Transport

Network

BundleBundle Bundle

Network of internets spanning dissimilar environments

Inter-Internet Dialog: Design Principles

Names are the means of referenceRouting between domains based upon names

Late-BindingSeparate addressing domains for each internet; names converted to local addresses in destination domain

IndirectionInherent dependence on intermediate relay agents

Custodial transfer“Bundles” as a common end-to-end mailing mechanism

DeployedInternets

StableBackbone

Security

InterplanetaryGateways

Inter-Internet Dialogand Nodes

Bundled Data Transfers

Traffic is inherently non-interactive

• A single self-contained request generates a single self-contained response • Distinctly taciturn, “non-chatty” dialog

Bundling Protocol lives above the local transport protocols, but below end-to-end applications

• Minimally, carries names end-to-end in “metadata”• Potential applicability to new Internet applications

DeployedInternets

StableBackbone

Security

InterplanetaryGateways

Inter-Internet Dialogand Nodes

Single Name Space,Late Name-to-Address Binding(s)

Internet InternetInterplanetaryBackbone

Name Space - Common Across All Internets

Name-to-Address Binding Space A

Name-to-Address Binding Space B

Name-to-Address Binding Space C

http://www.rockshop.com.mars.sol137.79.10.232

http://www.bughunter.org.earth.sol137.79.10.232

.mars.sol.earth.sol .ipn.sol

From Telephony Back to the Pony Express Custody Transfers and Bundles

Custody Transfers

InterplanetaryBackbone

Internet Internet

“Return Receipt”

“Shipping Receiptand Tracking #”

R R

A A

IPN Relay: mitigation for R2 effects; no custody transfer

A

R

Bundle Agent: builder and consumer of bundles

IPN Gateway: custody transfer and routing between IPN domains

G

G

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IPN Security

Security of user data flowing through the IPN

Security of the IPN backbone

DeployedInternets

StableBackbone

Security

InterplanetaryGateways

Inter-Internet Dialogand Nodes

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IPN Security Requirements

access control to the IPN will be required because space-based assets will have limited available resources.

authentication will be required to perform access controls.

data integrity will be required to assure that what was sent is received.

data privacy will be required to assure that unauthorized users cannot obtain information.

• We can only have end-to-end security where there are end-to-end protocols, so:

- security cannot be performed in the IPN at transport or below IPSEC

• In the IPN, end-to-end protocols (e.g. TCP) are terminated at the IPN gateways

.• End-to-end like security can only be applied to the data (e.g.,TLS/SSL, S/email)

- is TLS/SSL the right answer (many round-trip negotiations)? NO!- is secure email model is a better fit? YES- key management - “PKI to the Planets?”

IPN Security Constraints

Mars may need women, but...

The IPN Needs ParticipantsHelp expand the gene pool:

Robert Rumeau (CNES)Centre National d'Etudes SpatialesToulouse CEDEXRumeau@cnes.fr

Eric Travis (NASA)Global Science and Technology, Inc.Greenbelt, Maryland 20770 USAtravis@gst.com(Dinosaurs Welcome; Spacecraft optional)