[ih] TCP RTT Estimator

[Greg Skinner]

On Mar 11, 2025, at 7:05 AM, David Finnigan via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> It looks like staff at RSRE (Royal Signals and Radar Establishment) took
> the lead in experimenting with formulae and methods for dynamic
> estimation of round trip times in TCP. Does anyone here have any further
> insight or recollection into these experiments for estimating RTT, and
> the development of the RTT formula?
> 
> -David Finnigan
> -- 
> Internet-history mailing list
> Internet-history at elists.isoc.org
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During the standardization process of RFC 9293, I learned from Wes Eddy, the RFC 9293 editor, about an adaptive retransmission timeout algorithm paper written by Stephen Edge of UCL. [1] While this paper was published after then IENs you mentioned were written, the principles discussed in it may have influenced the RSRE work that eventually led to the RTT estimation strategy and formula that was incorporated into RFC 793.

You might also consider Dave Mills’ remarks in Section 3 of RFC 889.  Although it was also published after the IENs you mentioned were written, he may have had some insight into why additional work was needed to generally improve TCP performance.

--gregbo

[1] https://dl.acm.org/doi/pdf/10.1145/800056.802085