Date: Thu, 05 Apr 2018 20:46:23 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-net@FreeBSD.org Subject: [Bug 227303] tcp cwnd grows without bounds while app/rwnd limited, interacts badly with rwnd autosize Message-ID: <bug-227303-2472-StDcHsx8Cm@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-227303-2472@https.bugs.freebsd.org/bugzilla/> References: <bug-227303-2472@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=227303 --- Comment #2 from Richard Scheffenegger <srichard@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. -- You are receiving this mail because: You are the assignee for the bug.
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