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TCP Extensions for Space Communication (aka SCPS-TP)
R.C. Durst and G.J. Miller (MITRE) and E.J. Travis (Gemini Industries)
Roll together many TCP-for-wireless optimizations, but change them
slightly, in order to adapt TCP for communication with satellites, the
space shuttle, etc.
- Standard problems: long fat pipe; errors from radiation, etc. may
be bursty or periodic (orbit); asymmetric (typ. 1000:1); TCP
aborts after n retransmissions
- Use TCP Vegas (RTT, not loss, indicates congestion). Since
doesn't use receive window size as upper bound on pipe filling,
enables large windows for long fat network.
- Use open loop rate control rather than ACKs to clock out data.
- Explicit notification via ICMP of corruption or outage from
downstream routers: sources enter persistent mode, probing until
outage goes away. When no explicit notification, assume a
default cause of loss (configurable).
- Use "stateless" TCP header compression (similar to RFC ??? but
nonconformant) to avoid "cascading loss" problem.
- Use selective NAK rather than go-back-N (similar to RFC 2018, but
TCP In Space! About time we started adapting proven protocols rather
than rewriting from scratch for each mission (this is what NASA has done
- Too bad it's non-interoperable, but the changes seem
innocuous and could be handled in gateway routers.
- Except for the
explicit notification of reason for lossage, this is just all of
the wireless TCP improvements rolled into one.
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