From owner-freebsd-net@FreeBSD.ORG Mon Oct 27 23:02:22 2008 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CA300106566B for ; Mon, 27 Oct 2008 23:02:22 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout012.mac.com (asmtpout012.mac.com [17.148.16.87]) by mx1.freebsd.org (Postfix) with ESMTP id B620B8FC18 for ; Mon, 27 Oct 2008 23:02:22 +0000 (UTC) (envelope-from cswiger@mac.com) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Received: from cswiger1.apple.com ([17.227.140.124]) by asmtp012.mac.com (Sun Java(tm) System Messaging Server 6.3-7.03 (built Aug 7 2008; 32bit)) with ESMTPSA id <0K9F00J2F3VV5R50@asmtp012.mac.com> for freebsd-net@freebsd.org; Mon, 27 Oct 2008 15:02:19 -0700 (PDT) Message-id: <1AB022D4-5147-4837-82CC-99270FF45AE5@mac.com> From: Chuck Swiger To: Eitan Shefi In-reply-to: <5D49E7A8952DC44FB38C38FA0D758EADCC5FB7@mtlexch01.mtl.com> Date: Mon, 27 Oct 2008 15:02:18 -0700 References: <5D49E7A8952DC44FB38C38FA0D758EADC72E72@mtlexch01.mtl.com> <5D49E7A8952DC44FB38C38FA0D758EADCC5FB7@mtlexch01.mtl.com> X-Mailer: Apple Mail (2.929.2) Cc: freebsd-net@freebsd.org Subject: Re: It seems that FreeBSD-7.0 does not use the available MTU 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: Mon, 27 Oct 2008 23:02:22 -0000 On Oct 27, 2008, at 2:53 PM, Eitan Shefi wrote: > When I change the MTU to a value greater then 1500, for example 3000, > and then send "ping" with message size 2500, from one host to the > other, > the other host gets more then one ICMP packet, even thaw the message > that was send is match smaller then the MTU. > > I tried to run this test using a different NIC, but I got the same > behavior. You obscured the details of which NICs you actually used, so a guess would be that your hardware doesn't support jumbo frames. If your NIC isn't gigabit-speed capable, this is probably expected-- only fairly new NICs like em/bce/bge/msk have the capability. Regards, -- -Chuck