From owner-freebsd-hackers@FreeBSD.ORG Sat Feb 7 02:42:27 2015 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id C1A46A3B for ; Sat, 7 Feb 2015 02:42:27 +0000 (UTC) Received: from na01-bl2-obe.outbound.protection.outlook.com (mail-bl2on0090.outbound.protection.outlook.com [65.55.169.90]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client CN "mail.protection.outlook.com", Issuer "MSIT Machine Auth CA 2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5F4C63C9 for ; Sat, 7 Feb 2015 02:42:26 +0000 (UTC) Received: from DM2PR0801MB0944.namprd08.prod.outlook.com (25.160.131.27) by DM2PR0801MB0942.namprd08.prod.outlook.com (25.160.131.25) with Microsoft SMTP Server (TLS) id 15.1.75.20; Sat, 7 Feb 2015 02:42:24 +0000 Received: from DM2PR0801MB0944.namprd08.prod.outlook.com ([25.160.131.27]) by DM2PR0801MB0944.namprd08.prod.outlook.com ([25.160.131.27]) with mapi id 15.01.0075.002; Sat, 7 Feb 2015 02:42:24 +0000 From: "Pokala, Ravi" To: "freebsd-hackers@freebsd.org" Subject: Changing the MTU on a lagg device Thread-Topic: Changing the MTU on a lagg device Thread-Index: AQHQQn+0qPs6AFh2xkSO1q7r/b61ug== Date: Sat, 7 Feb 2015 02:42:24 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.4.7.141117 x-originating-ip: [64.80.217.3] authentication-results: freebsd.org; dkim=none (message not signed) header.d=none; x-microsoft-antispam: BCL:0;PCL:0;RULEID:;SRVR:DM2PR0801MB0942; x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:; SRVR:DM2PR0801MB0942; x-forefront-prvs: 0480A51D4A x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(6009001)(164054003)(229853001)(107886001)(2900100001)(102836002)(87936001)(46102003)(86362001)(106116001)(99286002)(83506001)(110136001)(2351001)(40100003)(92566002)(122556002)(77156002)(62966003)(66066001)(450100001)(50986999)(2656002)(54356999)(36756003); DIR:OUT; SFP:1101; SCL:1; SRVR:DM2PR0801MB0942; H:DM2PR0801MB0944.namprd08.prod.outlook.com; FPR:; SPF:None; MLV:sfv; LANG:en; Content-Type: text/plain; charset="us-ascii" Content-ID: <69EB68B571C326499A1ED92316BE961F@namprd08.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: panasas.com X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Feb 2015 02:42:24.5312 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: acf01c9d-c699-42af-bdbb-44bf582e60b0 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM2PR0801MB0942 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 07 Feb 2015 02:42:27 -0000 Hi folks, Let's say you have lagg0, consisting of if0 and if1. If you want to change the MTU, you have to remove if0 and if1 from the lagg, change their MTUs, and add them back; that is: 1) ifconfig lagg0 -laggport if0 2) ifconfig lagg0 -laggport if1 3) ifconfig if0 mtu 9000 4) ifconfig if1 mtu 9000 5) ifconfig lagg0 laggport if0 6) ifconfig lagg0 laggport if1 It would be nice if this could be done with a single command: 1) ifconfig lagg0 mtu 9000 Panasas implemented that functionality for our older base FreeBSD, and we're looking to port it forward and push it upstream. However, it looks like someone thought about this case and explicitly decided not to do it; if_lagg.c has: case SIOCSIFMTU: /* Do not allow the MTU to be changed once joined */ error =3D EINVAL; break; Does anyone know why that is? Would anyone object to a patch that lets you change the MTU on the lagg device, and having the lagg driver change it on all the component interfaces for you? Thanks, Ravi