TCP Fast Open
jgh at wizmail.org
Fri Dec 6 14:23:13 UTC 2019
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
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
- 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.
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