[Bug 227303] tcp cwnd grows without bounds while app/rwnd limited, interacts badly with rwnd autosize

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=227303

--- Comment #2 from Richard Scheffenegger <srichard at netapp.com> ---
After further investigation, this issue is more complex. cwnd does in fact not
grow when the transmission is rwnd limited. However, 20 sec prior to these two
burst events, during slow start, the client already signaled a large rwnd (at
least as large as when the bursts happen). And no losses occured, so cwnd did
probably grow to the large rwnd (or very close to is) during the initial slow
start. Then, the client reduced rwnd to 1/2 or 1/3 of that initial value, and
cwnd never decays (RTT is 1ms with empty buffers, and 40ms with full buffers;
20 sec are eons in any case). 

So at the time of these graphs, cwnd has no longer any valid information about
the state of the network, but is nevertheless used as such.

Guess RFC7661 (with substituting "no transmissions" with "transmission rate <
cwnd") with it's many-rtt long decay would adress this particular issue.

Can provide xpl file (but not original trace) of the entire session.

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