Fw: [Bug 93901] New: TCP Fast Open uses

Fw: [Bug 93901] New: TCP Fast Open uses

[Stephen Hemminger]

Begin forwarded message:

Date: Thu, 26 Feb 2015 15:43:45 +0000
From: "bugzilla-daemon@bugzilla.kernel.org" <bugzilla-daemon@bugzilla.kernel.org>
To: "shemminger@linux-foundation.org" <shemminger@linux-foundation.org>
Subject: [Bug 93901] New: TCP Fast Open uses


https://bugzilla.kernel.org/show_bug.cgi?id=93901

            Bug ID: 93901
           Summary: TCP Fast Open uses
           Product: Networking
           Version: 2.5
    Kernel Version: 4.0-rc1
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: low
          Priority: P1
         Component: IPV4
          Assignee: shemminger@linux-foundation.org
          Reporter: rueth@comsys.rwth-aachen.de
        Regression: No

TCP Fast Open still uses the TCP Experimental Option even though RFC7413
advises not to use the experimental options field anymore but rather use IANA
assigned option number 34 (https://tools.ietf.org/html/rfc7413#section-9).

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Re: Fw: [Bug 93901] New: TCP Fast Open uses

[Eric Dumazet]

On Thu, 2015-02-26 at 08:07 -0800, Stephen Hemminger wrote:
> 
> Begin forwarded message:
> 
> Date: Thu, 26 Feb 2015 15:43:45 +0000
> From: "bugzilla-daemon@bugzilla.kernel.org" <bugzilla-daemon@bugzilla.kernel.org>
> To: "shemminger@linux-foundation.org" <shemminger@linux-foundation.org>
> Subject: [Bug 93901] New: TCP Fast Open uses
> 
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=93901
> 
>             Bug ID: 93901
>            Summary: TCP Fast Open uses
>            Product: Networking
>            Version: 2.5
>     Kernel Version: 4.0-rc1
>           Hardware: All
>                 OS: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: low
>           Priority: P1
>          Component: IPV4
>           Assignee: shemminger@linux-foundation.org
>           Reporter: rueth@comsys.rwth-aachen.de
>         Regression: No
> 
> TCP Fast Open still uses the TCP Experimental Option even though RFC7413
> advises not to use the experimental options field anymore but rather use IANA
> assigned option number 34 (https://tools.ietf.org/html/rfc7413#section-9).

This is work in progress at Google, of course.

Classic chicken and egg problem ;)

Thanks

Re: Fw: [Bug 93901] New: TCP Fast Open uses

[Rick Jones]

On 02/26/2015 08:13 AM, Eric Dumazet wrote:
> This is work in progress at Google, of course.
>
> Classic chicken and egg problem ;)

Does it need to be any more complicated than a sysctl which enables 
accepting an alternate (the experimental) option value in addition to 
the assigned, to be enabled (perhaps by default for a release or three) 
for the server side, and then just switching the active connection 
establishment side to the assigned number?

If the server is "old" and using the experimental version, the only 
thing that will happen is the clients using the standardized version 
will end-up falling back on the classic three-way handshake.  That 
doesn't seem so bad.  Particularly since that option value was 
"experimental" after all and presumably then not really meant for 
"production" purposes :)

rick jones

Re: Fw: [Bug 93901] New: TCP Fast Open uses

[Eric Dumazet]

On Thu, 2015-02-26 at 09:58 -0800, Rick Jones wrote:
> On 02/26/2015 08:13 AM, Eric Dumazet wrote:
> > This is work in progress at Google, of course.
> >
> > Classic chicken and egg problem ;)
> 
> Does it need to be any more complicated than a sysctl which enables 
> accepting an alternate (the experimental) option value in addition to 
> the assigned, to be enabled (perhaps by default for a release or three) 
> for the server side, and then just switching the active connection 
> establishment side to the assigned number?
> 
> If the server is "old" and using the experimental version, the only 
> thing that will happen is the clients using the standardized version 
> will end-up falling back on the classic three-way handshake.  That 
> doesn't seem so bad.  Particularly since that option value was 
> "experimental" after all and presumably then not really meant for 
> "production" purposes :)

Really, if you are eager to see this coming, you could send a patch.

Or simply wait for the work being done by a Googler ;)

<quote Google-Bug-Id: 19264158 >

Add support to use RFC7413 option (34) for TCP Fast open while
supporting the old/current experimental option format. The idea is
a new client will request fast open cookie using option 34 
if the SYN-ACK contains TFO cookie with option 34. everything works out.
otherwise, the client retries the cookie request with the exp option in
the subsequent TFO connection attempt. if the server grants the cookie,
records the destination is an old server for the next (30?) days.
a new  server will respond TFO cookie based on the option number used in
cookie request.

</quote>