From owner-freebsd-net@FreeBSD.ORG Tue Mar 21 04:06:42 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id F29E516A401 for ; Tue, 21 Mar 2006 04:06:42 +0000 (UTC) (envelope-from lists@wm-access.no) Received: from lakepoint.domeneshop.no (lakepoint.domeneshop.no [194.63.248.54]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1864743D58 for ; Tue, 21 Mar 2006 04:06:41 +0000 (GMT) (envelope-from lists@wm-access.no) Received: from [192.168.5.8] (host-81-191-3-170.bluecom.no [81.191.3.170]) (authenticated bits=0) by lakepoint.domeneshop.no (8.13.4/8.13.4) with ESMTP id k2L46bST028004 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 21 Mar 2006 05:06:38 +0100 Message-ID: <441F6FE0.80108@wm-access.no> Date: Tue, 21 Mar 2006 04:15:44 +0100 From: =?ISO-8859-1?Q?Sten_Daniel_S=F8rsdal?= User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: freebsd-net@freebsd.org X-Enigmail-Version: 0.94.0.0 OpenPGP: id=D6F56A9B Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig113F66475413567CE9F02618" Subject: How can i detect if a received UDP got fragmented from userland? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Mar 2006 04:06:43 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig113F66475413567CE9F02618 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable I am currently working on a udp multicast application written in C for FreeBSD (6.x) For our test cases in many different network types we found that fragmentation poses as a significant problem for quality and reliability.= Packets that get fragmented are more likely to get dropped than packets that do not get fragmented and since our application needs high=20 bulk performance without retransmissions we believe our application and=20 the network would benefit from this. Our first assumption was that adding DF to UDP would solve it, and it does in our small tests, but it has a noticable negative effect on the=20 network. Are there any way i can read whether a message's packet was fragmented=20 into smaller pieces and preferably how large the largest fragment was? Are there any feasible way to do this? Thank you for your time. --=20 Sten Daniel S=F8rsdal --------------enig113F66475413567CE9F02618 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEH2/lMvOF8Nb1apsRAqS9AJ9qD8f2UWV5986QNUcln1o5MYOq1QCfeXZ3 DFC1N1nWnc+6+X9s8TolOS0= =2dEj -----END PGP SIGNATURE----- --------------enig113F66475413567CE9F02618--