From owner-freebsd-cloud@FreeBSD.ORG Thu Mar 12 20:59:56 2015 Return-Path: Delivered-To: freebsd-cloud@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 4CADAA3F for ; Thu, 12 Mar 2015 20:59:56 +0000 (UTC) Received: from o3.shared.sendgrid.net (o3.shared.sendgrid.net [208.117.48.85]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 087F3A3B for ; Thu, 12 Mar 2015 20:59:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sendgrid.info; h=from:mime-version:to:subject:references:in-reply-to:content-type:content-transfer-encoding; s=smtpapi; bh=JwhCkdzfmOQwbW4ULmDLgKAAs50=; b=zjeCCYjLktMpeRd0Ua HaKAVLRXzzIQImBEXZs+oUrPQEA2EPN0sh3CG92YJXDsu46FcsLEVI6VtyhdIbNQ tamxPlzRzB4lyBp/xW6uG09lthyndsbhWs9YNWgUXVlHwKvQRiJ7k7tCg1tk7AQG wSmU0PK4DMxt72BPfBLSModZc= Received: by filter0170p1mdw1.sendgrid.net with SMTP id filter0170p1mdw1.20653.5501FE299 2015-03-12 20:59:26.284794404 +0000 UTC Received: from mail.tarsnap.com (ec2-54-86-246-204.compute-1.amazonaws.com [54.86.246.204]) by ismtpd-024 (SG) with ESMTP id 14c0fc8e494.1b8c.20251 for ; Thu, 12 Mar 2015 20:59:26 +0000 (UTC) Received: (qmail 40075 invoked from network); 12 Mar 2015 20:57:59 -0000 Received: from unknown (HELO clamshell.daemonology.net) (127.0.0.1) by ec2-107-20-205-189.compute-1.amazonaws.com with ESMTP; 12 Mar 2015 20:57:59 -0000 Received: (qmail 2288 invoked from network); 12 Mar 2015 20:57:09 -0000 Received: from unknown (HELO clamshell.daemonology.net) (127.0.0.1) by clamshell.daemonology.net with SMTP; 12 Mar 2015 20:57:09 -0000 Message-ID: <5501FDA5.9050903@freebsd.org> Date: Thu, 12 Mar 2015 13:57:09 -0700 From: Colin Percival User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: "Bradley T. Hughes" , freebsd-cloud@freebsd.org Subject: Re: FreeBSD/EC2 - MTU on xn0? References: <708D692E-ED5D-421F-94C3-1984B95E0296@fastmail.fm> In-Reply-To: <708D692E-ED5D-421F-94C3-1984B95E0296@fastmail.fm> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SG-EID: XhyBwObMhraAR+zdwMupjd7LSrZ36RouVZZW3oDOpB3CUiNYQ5mq5gKGTBgikFobZlQlz0rH9t5mqx t7vXQ/AF7XhLrj6/jhZ922YCQSnIhPGAVKOGn6hDqRATJ1DFFG2qY9mYrv9UEe79j4CW9ObIpF/nbX Xas4PqmYk0VIu7Flw0+lA5mBo/ZoPCf1kbUb X-BeenThere: freebsd-cloud@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "FreeBSD on cloud platforms \(EC2, GCE, Azure, etc.\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Mar 2015 20:59:56 -0000 On 03/12/15 13:29, Bradley T. Hughes wrote: > The AWS EC2 Instance Types documentation[1] says that the MTU for the network interfaces is dependent on the instance type. A post on the AWS forums[2] by an AWS representative states that the MTU configuration is available via DHCP. Huh, I did not know EC2 supported jumbo frames. > I noticed that all of our T2 instances running FreeBSD have an MTU of 1500. After searching around a bit, I found this patch[3]. I get the same results when running the reproduction steps in EC2, despite ifconfig(8) saying it's using an MTU of 9001. > > I'm wondering if the patch in 187094 is what's needed to make the xn0 interface on our FreeBSD instances use jumbo frames? I have absolutely no clue. This might be a question for -xen or -net since it's not specific to EC2 (and there are more people on those lists). -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid