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Re: Fwd: Re: [tcpm] FW: Call for Adoption: TCP Tuning for HTTP

From: Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
Date: Sat, 5 Mar 2016 05:27:34 -0800
Message-ID: <CAO249ye6U29cxBbrP21_J5P=yaCOW9uNEfqJqyM-WBCUDmToNg@mail.gmail.com>
To: Willy Tarreau <w@1wt.eu>
Cc: Joe Touch <touch@isi.edu>, ietf-http-wg@w3.org
Hi Willy,

On Thu, Mar 3, 2016 at 1:11 PM, Willy Tarreau <w@1wt.eu> wrote:

> Let me restate it :
>   - the client cannot bypass the TW state because it has no way to know
>     whether or not the server has closed after seeing the last ACK or
>     is still waiting for it.
>   - the server when it sees a SYN with an ISN larger than the end of the
>     previous window, *knows* that the client has closed, otherwise the
>     client would be in LAST_ACK and couldn't send a SYN in this state.
>     This is why servers recycle connections, and only in this case.

Hmm, If there are multiple clients behind a NAT, the server cannot know if
it´s coming from the same one or difference one.
Also each client uses its own ISN (also timestamp). So, in this case, it is
possible that the server will see a SYN from different client with an ISN
smaller than the previous window or staled timestamp.
In this case, I guess server will send back old FIN ACK or reset, which
causes the termination of the connection anyway.
If clients go into TIME_STATE, I think we can avoid this.

Received on Saturday, 5 March 2016 13:28:06 UTC

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