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.