[Sis-csi] noting unusual CCSDS security critique

[Max Repaci]

We are in the process of finishing up a study on the application
of TCP to space communications. We have found that by using
SCPS-TP as a proxy for TCP over the space link the data rates
you specified below can be achieved, provided the packet loss
rate is not too much higher than 1% (effective BER of 1e-6).

We will post our report to this list when it's done.

----
Max Repaci
Global Protocols, Inc.


Lloyd Wood wrote:

> 
> The paper does not discuss TCP implementations. The paper discusses
> the design of TCP not being suitable for the scenario.
> 
> You can't get TCP to run at any decent rate over 8Mbps down/9600bps
> back; the bottleneck on the acks is a major constraint, and you'll
> never get out of slow start. TCP's probing of available capacity to
> ensure fairness is not useful when you're scheduling access to the
> downlink and are concerned with link utilization across the downlink.
> Given that TCP's design is clearly not suitable for this scenario, why
> go to the trouble of running an implementation?
> 
> (I gather CHIPSat uses ftp to a ground station to transfer data over
> its 432kbps downlink -- but it's not transferring much data. And even
> then, the ftp/TCP transfer is across the wireless link to the ground
> station to minimise network effects from shared longer paths.)
> 
> L.
> 
> <http://www.ee.surrey.ac.uk/Personal/L.Wood/><L.Wood at eim.surrey.ac.uk>
> 
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