[tcpm] RFC 2883 (D-SACK), Section 5.1 Replication by the network

Alexander Zimmermann <Alexander.Zimmermann@nets.rwth-aachen.de> Thu, 06 November 2008 08:26 UTC

Return-Path: <tcpm-bounces@ietf.org>
X-Original-To: tcpm-archive@megatron.ietf.org
Delivered-To: ietfarch-tcpm-archive@core3.amsl.com
Received: from [] (localhost []) by core3.amsl.com (Postfix) with ESMTP id C05513A697D; Thu, 6 Nov 2008 00:26:02 -0800 (PST)
X-Original-To: tcpm@core3.amsl.com
Delivered-To: tcpm@core3.amsl.com
Received: from localhost (localhost []) by core3.amsl.com (Postfix) with ESMTP id E6BE23A6952 for <tcpm@core3.amsl.com>; Thu, 6 Nov 2008 00:26:01 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.01
X-Spam-Status: No, score=-4.01 tagged_above=-999 required=5 tests=[AWL=-0.204, BAYES_00=-2.599, FS_REPLICA=0.994, HELO_EQ_DE=0.35, HELO_MISMATCH_DE=1.448, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([]) by localhost (core3.amsl.com []) (amavisd-new, port 10024) with ESMTP id eTBpVwxyHgcx for <tcpm@core3.amsl.com>; Thu, 6 Nov 2008 00:26:00 -0800 (PST)
Received: from mta-1.ms.rz.rwth-aachen.de (mta-1.ms.rz.RWTH-Aachen.DE []) by core3.amsl.com (Postfix) with ESMTP id BE1CB3A6903 for <tcpm@ietf.org>; Thu, 6 Nov 2008 00:26:00 -0800 (PST)
Received: from ironport-out-1.rz.rwth-aachen.de ([]) by mta-1.ms.rz.RWTH-Aachen.de (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) with ESMTP id <0K9W00I9JKR9C190@mta-1.ms.rz.RWTH-Aachen.de> for tcpm@ietf.org; Thu, 06 Nov 2008 09:25:57 +0100 (CET)
Received: from smarthost-2.ms.rz.rwth-aachen.de (HELO smarthost.rwth-aachen.de) ([]) by ironport-in-1.rz.rwth-aachen.de with ESMTP; Thu, 06 Nov 2008 09:25:57 +0100
Received: from chicago.informatik.RWTH-Aachen.DE (chicago.informatik.RWTH-Aachen.DE []) by smarthost.rwth-aachen.de (8.13.8+Sun/8.13.8/1) with ESMTP id mA68PugR004663; Thu, 06 Nov 2008 09:25:56 +0100 (CET)
Date: Thu, 06 Nov 2008 09:25:55 +0100
From: Alexander Zimmermann <Alexander.Zimmermann@nets.rwth-aachen.de>
To: tcpm@ietf.org
Message-id: <5896054F-1A61-4BAC-94B0-F89660190A53@nets.rwth-aachen.de>
MIME-version: 1.0
X-Mailer: Apple Mail (2.929.2)
X-IronPort-AV: E=Sophos;i="4.33,556,1220220000"; d="sig'?scan'208,217";a="89476742"
X-Pgp-Agent: GPGMail d53 (v53, Leopard)
Subject: [tcpm] RFC 2883 (D-SACK), Section 5.1 Replication by the network
X-BeenThere: tcpm@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: TCP Maintenance and Minor Extensions Working Group <tcpm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://www.ietf.org/mailman/private/tcpm>
List-Post: <mailto:tcpm@ietf.org>
List-Help: <mailto:tcpm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=subscribe>
Content-Type: multipart/mixed; boundary="===============2130511456=="
Sender: tcpm-bounces@ietf.org
Errors-To: tcpm-bounces@ietf.org

Hi folks,

RFC 2883, Section 5.1 states that without D-SACK a TCP sender would
not know that a packet had been replicated in the network if the last  
was piggybacked on a data packet.

According 2581(bis) a TCP receiver should send immediately an DUPACK
when an out-of-order segment arrives. Furthermore, 2581bis says that a
DUPACK carries no data.

So, according to the DUPACK definition of 2581bis it seems to me that we
have no problem to detect a packet replication in case D-SACK is not
present. Right?


// Dipl.-Inform. Alexander Zimmermann
// Department of Computer Science, Informatik 4
// RWTH Aachen University
// Ahornstr. 55, 52056 Aachen, Germany
// phone: (49-241) 80-21422, fax: (49-241) 80-22220
// email: zimmermann@cs.rwth-aachen.de
// web: http://www.umic-mesh.net

tcpm mailing list