Notes
Outline
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Slide 15
Deployed Internets: A Broad Range of Possible Configurations
A single lander with an IPN gateway to a (real or virtual) internal network
Small number of cooperating robots on planetary surface (e.g. Single lander, single rover)
Orbiter-to-surface communication and coordination (e.g. sample return recovery)
Multiple beyond-line-of-sight missions connected by low-orbit communication satellites
Planet-stationary satellites for relay and gateway functions
Spacecraft on-board LANs
The Earth’s Internet
Some Functions of Deployed Internets
Science Data and Telemetry Return
Command and Control of In-Situ Elements
Telescience/Virtual Presence
Initially back-hauled to earth
Secondarily, in support of robotic control of robotic exploration
Eventually, in support of human in situ control of robotic exploration
Differences between IPN remotely-deployed
internets and the terrestrial Internet
Power Management is of Preeminent Importance
Power availability affects all aspects of deployed internet operation
Solar conversion is the primary power source for foreseeable future
Example:  The average solar intensity in Mars orbit is 590 W/m2, compared with 1370 W/m2 in Earth orbit
Surface-based solar panels are subject to
Atmospheric dust limiting available solar energy
Dust build-up on/erosion of solar panels, reducing effectiveness over time
Location-based reductions in solar intensity
Seasonal variations in solar intensity
Efficiency of communication at all layers is required to offset the limitations of power availability
Terrestrial “Edge” Technologies with Potential In-situ Use
Slide 21
What’s a Backbone?
A set of high-capacity, high-availability links between network traffic hubs
Terrestrial backbone links are between hubs like Houston and Chicago.
Interplanetary backbone links are between hubs like Earth and Mars.
Differences Between Terrestrial and Interplanetary Backbones
What These Differences Imply
Cost per second of transmission is very high, so…
Don’t waste transmission opportunities.
Intra-backbone connectivity might never be end-to-end, so…
Don’t rely on end-to-end connectivity for protocol operations.  Use store-and-forward techniques.
End-to-end round trip time may vary from minutes to weeks, so…
Don’t rely on negotiation or other conversational protocol mechanisms; by the time a conversation converges, the reason for it may have passed.  Make protocol decisions autonomously, locally.
Resulting Backbone Differences
How Far Have We Gotten?
There is a working prototype: the CCSDS File Delivery Protocol (CFDP).
Architecturally very similar to IPN.
International standard, four experimental implementations.
Baselined for Deep Impact mission, potentially others.
But CFDP was designed to support individual space flight missions, not to serve as the infrastructure for a permanent, general-purpose network.
Addressing scheme is simple but limited.
Application, transport, network, and reliable link layers are combined into a single protocol, which only does file transfer.
Specification of proposed IPN protocols is under way.
Slide 27
Interplanetary Dialogs:
Design Principles
Intermittent connectivity suggests an Email-like architecture
Common “Handling Instructions” for a data collection
Network must accommodate the persistence and transfer of state
Names (not addresses) are the means of reference
Names have two parts:  a routing part (specifies the IPN
region) and an administrative part (specifies the DNS name)
Routing between IPN regions based upon routing part of the name
Late-Binding
Separate addressing domains for each internet; administrative names converted to local addresses only at the destination IPN region
Indirection
Inherent dependence on intermediate relay agents
Custodial transfer
Intermediate nodes assume possibly-long-term responsibility for data forwarding
“Bundles” as a common end-to-end transfer mechanism
Slide 29
Slide 30
Bundling Spans Temporal Discontinuities Between Networks
Single Name Space,
Late Name-to-Address Binding(s)
The Interplanetary Internet:
An overlay network  for interconnection of regional internets
A region is an area where the relevant characteristics of communication are homogeneous
One can define regions that are based upon:
Communications capability
Quality of Service Peerings
Security (levels of trust)
Degree of resource management
Etc.
Traversal of two or more regions will effect the nature of communications
Interplanetary Dialogs In a Terrestrial Context