From owner-freebsd-net@FreeBSD.ORG Thu Nov 28 16:02:14 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 67C4BD18 for ; Thu, 28 Nov 2013 16:02:14 +0000 (UTC) Received: from mail1.multiplay.co.uk (mail1.multiplay.co.uk [85.236.96.23]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 0331E166D for ; Thu, 28 Nov 2013 16:02:13 +0000 (UTC) Received: from r2d2 ([82.69.179.241]) by mail1.multiplay.co.uk (mail1.multiplay.co.uk [85.236.96.23]) (MDaemon PRO v10.0.4) with ESMTP id md50006862913.msg for ; Thu, 28 Nov 2013 16:02:09 +0000 X-Spam-Processed: mail1.multiplay.co.uk, Thu, 28 Nov 2013 16:02:09 +0000 (not processed: message from valid local sender) X-MDDKIM-Result: neutral (mail1.multiplay.co.uk) X-MDRemoteIP: 82.69.179.241 X-Return-Path: prvs=1044cd13f0=killing@multiplay.co.uk X-Envelope-From: killing@multiplay.co.uk X-MDaemon-Deliver-To: freebsd-net@freebsd.org Message-ID: <0F2B39164CA846AFBBE0EF697EFE3407@multiplay.co.uk> From: "Steven Hartland" To: "Marc Olzheim" , "Meny Yossefi" References: <20131128124944.GA15691@zlo.nu> Subject: Re: UDP traffic, msg size exceeds 9215 Bytes Date: Thu, 28 Nov 2013 16:02:03 -0000 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Cc: freebsd-net@freebsd.org, Oded Shanoon X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.16 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Nov 2013 16:02:14 -0000 You really shouldnt allow the application to send packets that big as you'll end up with fragmentation and due to UDP protocol issues and hackers abusing them (the port for fragemented packets isn't set) you'll often find fragmented udp packets are simply blocked. Regards Steve ----- Original Message ----- From: "Marc Olzheim" To: "Meny Yossefi" Cc: ; "Oded Shanoon" Sent: Thursday, November 28, 2013 12:49 PM Subject: Re: UDP traffic, msg size exceeds 9215 Bytes > On Thu, Nov 28, 2013 at 12:43:43PM +0000, Meny Yossefi wrote: >> Hi all, >> >> We've been running some benchmarks (Netperf, Iperf) on our driver (Mellanox), and witnessed an odd behavior. >> We saw that when running UDP traffic with msg size larger than 9215 bytes, it gets dropped for some reason. MTU is 1500. >> >> We've spotted the same behavior on different vendors which lead us to believe there's some kernel issue that we are missing >> here. > > Did you meddle with sysctl net.inet.udp.maxdgram yet ? The default value is > 6 * 1536 = 9216 bytes... > > Marc > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > ================================================ This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337 or return the E.mail to postmaster@multiplay.co.uk.