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
IG
IG
IGIG
IG IG
I iiii
ii
ii
i iii
Ii
iii I
iii I
mars.sol luna.sol
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
G
G
IPN Security
Security of user data flowing through the IPN
Security of the IPN backbone
DeployedInternets
StableBackbone
Security
InterplanetaryGateways
Inter-Internet Dialogand Nodes
IG
IG
IGIG
IG IG
I iiii
ii
ii
i iii
Ii
iii I
iii I
mars.sol luna.sol
earth.sol
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 [email protected]
Eric Travis (NASA)Global Science and Technology, Inc.Greenbelt, Maryland 20770 [email protected](Dinosaurs Welcome; Spacecraft optional)