[ih] TCP RTT Estimator

[Joe Touch]

> On Apr 12, 2025, at 7:33 PM, Jack Haverty via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> The general principle was that the "on the wire" formats and meanings were standardized, so that any implementation of TCP could communicate with any other implementation.

“On the wire” all protocols are groups of bits. Even if some patterns are prohibited, that’s still not a protocol. 

A protocol is a tuple of wire messages sent/received, time events occurring/set up, user messages produced/consumed, and FSM relating them all. The “on the wire” part is 2/7 of that and never enough to endure comm. Decades of advice to the contrary not withstanding (the IETF rule that even generic APIs were not part of a protocol). 

The specific parts of TCP that were left “floating” may be interoperable but might not too. Two endpoints’ timeouts or calculations could interact in ways that grind data  xfer to a halt. 

So that principle above may have worked mostly well enough for TCP so far, it fails as “general”. 

Joe