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Re: Framing and control-frame continuations

From: Poul-Henning Kamp <phk@phk.freebsd.dk>
Date: Wed, 06 Feb 2013 08:51:27 +0000
To: Roberto Peon <grmocg@gmail.com>
cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <10784.1360140687@critter.freebsd.dk>
Content-Type: text/plain; charset=ISO-8859-1
--------
In message <CAP+FsNemzHOH1YrDXbEqy_dMB8h=e2pD0QrgLzkz+cUtdHMaRw@mail.gmail.com>
, Roberto Peon writes:

>  0        1        2        3        4         5        6        7
>  +--------+--------+--------+--------+--------+--------+--------+--------+
>  | Length(16)      |Type(8) |Flags(8)| Num-of-Entries-or-Stream-ID-or-ID | ->
>  +--------+--------+--------+--------+--------+--------+--------+--------+
>
>  8..N
>  +========+
>  |  Data  |
>  +========+
>
>   Length: An unsigned 16-bit value representing the number of bytes of
>   the data field.

I don't think this is good enough.

You'd need ~20k of these frames a second to fill a 10GB ethernet,
and a very large fraction of present day web-objects would require
more than one frame already.

We should take a clue from TCP's history of window-scaling and not
fence ourselves into 64kbytes for all time, nor should we make the
"X is enough for Y" mistake with a fixed horizon extension mechanism.

I suggest: 

  0               1               2
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Mantissa(14)              | E |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

	Length = Mantissa * 2^(8*E)

(I don't particularly care if we put the E field in the left or right side.)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
Received on Wednesday, 6 February 2013 08:51:50 GMT

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