Date: Fri, 6 Dec 2019 14:23:09 +0000 From: Jeremy Harris <jgh@wizmail.org> To: freebsd-transport@freebsd.org Subject: Re: TCP Fast Open Message-ID: <75f12c4d-63fb-40d5-8569-f8780de63521@wizmail.org> In-Reply-To: <70c1649f-b3b8-3c3b-ef80-22e851461e9f@wizmail.org> References: <5276cc23-d37f-e55e-11c5-030314e9e32c@wizmail.org> <1206B1BE-3B7E-45D0-8C2B-6012A5CB6298@freebsd.org> <2752006b-cd6b-7b8b-d23b-ae2c794dc104@wizmail.org> <f59092f1-9f93-d5c3-e7a2-06ba88bd7385@wizmail.org> <F24D850E-C6B6-4600-9B28-2439D70447A0@freebsd.org> <f07bb11e-4f69-b714-ce8d-881e68a20c6b@wizmail.org> <46A739DC-CCF5-4EA1-802A-0D8E559AC187@freebsd.org> <70c1649f-b3b8-3c3b-ef80-22e851461e9f@wizmail.org>
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On 05/12/2019 20:31, Jeremy Harris wrote: > On 05/12/2019 20:17, Michael Tuexen wrote: >>> - tried TFO but the server didn't take it up >> I would expect on = 0. > > Excellent; that's the most-useful one to know. Unfortunately, it seems not to be so; it appears to be recording the sending of a TFO option (of _either_ type; so a cookie-Request still gets it set). This means I can't use it to log "TFO was actually doing something useful for this connection". The TCPOPT_FAST_OPEN bit in TCP_INFO says the same (either pre-ESTABLISHED or post-). Another problem, this time server-side. I was hoping to get the initial server output piggybacked on the SYN,ACK, given the TFO design notes in https://people.freebsd.org/~pkelsey/TFO_Design_Details.pdf - but so far I'm not getting that. Packet capture (on lo0): SYN -> (TFO=C) 0.000224 <- SYN,ACK (TFO=C same value) 0.000078 SYN,ACK -> 0.001421 <- server_data The 224us response time for the SYN,ACK looks immediate, not a delack time as I'd expect. -- Cheers, Jeremy
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