Re: [hybi] frame length encoding

"Shelby Moore" <shelby@coolpage.com> Sun, 22 August 2010 17:54 UTC

Return-Path: <shelby@coolpage.com>
X-Original-To: hybi@core3.amsl.com
Delivered-To: hybi@core3.amsl.com
Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 0D9333A68F1 for <hybi@core3.amsl.com>; Sun, 22 Aug 2010 10:54:26 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.198
X-Spam-Level:
X-Spam-Status: No, score=-2.198 tagged_above=-999 required=5 tests=[AWL=0.401, BAYES_00=-2.599]
Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id n1tGES+iBuUi for <hybi@core3.amsl.com>; Sun, 22 Aug 2010 10:54:25 -0700 (PDT)
Received: from www5.webmail.pair.com (www5.webmail.pair.com [66.39.3.83]) by core3.amsl.com (Postfix) with SMTP id 16E993A6927 for <hybi@ietf.org>; Sun, 22 Aug 2010 10:54:25 -0700 (PDT)
Received: (qmail 49183 invoked by uid 65534); 22 Aug 2010 17:54:58 -0000
Received: from 121.97.54.174 ([121.97.54.174]) (SquirrelMail authenticated user shelby@coolpage.com) by sm.webmail.pair.com with HTTP; Sun, 22 Aug 2010 13:54:58 -0400
Message-ID: <bf7fd641553e15431d35d7352d023df2.squirrel@sm.webmail.pair.com>
In-Reply-To: <65fc5176b7cc6c775ec167f4404b43ed.squirrel@sm.webmail.pair.com>
References: <AANLkTimKbmcpgx8k0uXUWvCO=8w9pPrtV=3y4qh6363k@mail.gmail.com> <AANLkTinrsT+wV48nHvVW_1ChGYffkq7jisU2-PZnMyKg@mail.gmail.com> <alpine.DEB.2.00.1008212123460.27211@tvnag.unkk.fr> <20ef7ed5e135c57c1ee5a741658b9d98.squirrel@sm.webmail.pair.com> <1282423311.2014.6.camel@tng> <224b9ed365bd78fd5e316b8cb5f3f837.squirrel@sm.webmail.pair.com> <1282435214.2014.14.camel@tng> <AANLkTimo0MwZEMn1t1vrASfwC1bx82Q9Z_Ls3wVb-zUS@mail.gmail.com> <b95f074b65875865802f532bb5668ff2.squirrel@sm.webmail.pair.com> <AANLkTi=AXLFPSASV2zkBiUU=1StO=YSrKq_9AZ2ZnVHy@mail.gmail.com> <8cd6ecfebb4a073ecf94c8e1aa56e642.squirrel@sm.webmail.pair.com> <77aecf89c6c8673f1b999f80fa04e005.squirrel@sm.webmail.pair.com> <AANLkTik9tpCQr9LjK0qdLuA1KfJv1MN9yK2UZ1ytxfCW@mail.gmail.com> <fb8bfae1b88ade55cad4234af724004b.squirrel@sm.webmail.pair.com> <AANLkTimAu5de0PnujHRwR0nnXFBpqdJoRWZ=UvGrLVJ7@mail.gmail.com> <65fc5176b7cc6c775ec167f4404b43ed.squirrel@sm.webmail.pair.com>
Date: Sun, 22 Aug 2010 13:54:58 -0400
From: Shelby Moore <shelby@coolpage.com>
To: shelby@coolpage.com
User-Agent: SquirrelMail/1.4.20
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 8bit
X-Priority: 3 (Normal)
Importance: Normal
Cc: Hybi <hybi@ietf.org>
Subject: Re: [hybi] frame length encoding
X-BeenThere: hybi@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
Reply-To: shelby@coolpage.com
List-Id: Server-Initiated HTTP <hybi.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/hybi>, <mailto:hybi-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/hybi>
List-Post: <mailto:hybi@ietf.org>
List-Help: <mailto:hybi-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/hybi>, <mailto:hybi-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 22 Aug 2010 17:54:26 -0000

>> There is still a check of whether the value is the flag to indicate an
>> 8-byte length.  Having 2 compares to byte constants and associated
>> branches
>> instead of 1 compare to a short constant and a branch seems hardly a
>> significant additional processing requirement.

CLARIFICATION of the context:

I meant in the case where maximum size had been negotiated to 15-bits.

Of course Option 1/15-bit would still support 8 byte size when the maximum
size was negotiated to larger than 32767.

========
I hope everyone understands my point.  I am saying that if you are going
to assume that some routers will decided to negotiate a fixed maximum size
that has no conditional tests for size header, then it is more efficient
overall to use Option 1/15-bit, than Option 1 or Option 2.

It is a bit convoluted to understand, but I think my logic is correct. I
hope others convey that they understand or they correct my logic.