From owner-freebsd-net@FreeBSD.ORG Sat Sep 15 21:03:00 2007 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 B9E6216A417 for ; Sat, 15 Sep 2007 21:03:00 +0000 (UTC) (envelope-from SRS0=c40166501bd0870be4ada925990340ae3ca4aa35=459=es.net=oberman@es.net) Received: from postal1.es.net (postal1.es.net [IPv6:2001:400:14:3::6]) by mx1.freebsd.org (Postfix) with ESMTP id 444E213C458 for ; Sat, 15 Sep 2007 21:03:00 +0000 (UTC) (envelope-from SRS0=c40166501bd0870be4ada925990340ae3ca4aa35=459=es.net=oberman@es.net) Received: from ptavv.es.net (ptavv.es.net [198.128.4.29]) by postal1.es.net (Postal Node 1) with ESMTP (SSL) id UER66255; Sat, 15 Sep 2007 14:02:55 -0700 Received: from ptavv.es.net (ptavv.es.net [127.0.0.1]) by ptavv.es.net (Tachyon Server) with ESMTP id 1730A4500C; Sat, 15 Sep 2007 14:02:55 -0700 (PDT) To: Randy Bush In-Reply-To: Your message of "Sat, 15 Sep 2007 06:55:17 -1000." <46EC0E75.5070307@psg.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1189890175_21733P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Sat, 15 Sep 2007 14:02:55 -0700 From: "Kevin Oberman" Message-Id: <20070915210255.1730A4500C@ptavv.es.net> X-Sender-IP: 198.128.4.29 X-Sender-Domain: es.net X-Recipent: ;;; X-Sender: X-To_Name: Randy Bush X-To_Domain: psg.com X-To: Randy Bush X-To_Email: randy@psg.com X-To_Alias: randy Cc: FreeBSD Net , Julian Elischer Subject: Re: BCE on FreeBSD and oversized packet acceptance. 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: Sat, 15 Sep 2007 21:03:00 -0000 --==_Exmh_1189890175_21733P Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > Date: Sat, 15 Sep 2007 06:55:17 -1000 > From: Randy Bush > Sender: owner-freebsd-net@freebsd.org > > > what size is the actual maximal sized jumbo packet we will ever see? > > some transpac science community folk, who care more about speed trials > with big data sets than they do about over-stretching the ethernet crc, > use 9k jumbo frames. Almost the entire global R&E community uses 9K frames. This includes Internet2 (USA), Geant (Europe), Red Clara (S. America), CA*net (Canada), CUDI (Mexico), AMPATH (S. America), Transpac, Kreonet (Korea), NASA (USA), and ESnet (USA). 9000 (just to clarify the meaning of 'K') is the MTU recommended by the Joint Engineering Taskforce, a group which is a consortium of US and Canadian R&E networks and adopted almost universally in the global community. This will allow for multiple stacked VLAN and/or MPLS tags on an 8K byte data packet. Note that most systems use an 8192 byte IP MTU as that usually affords better performance as the data portion of the packet will fit in a single page of memory on most systems. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751 --==_Exmh_1189890175_21733P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) Comment: Exmh version 2.5 06/03/2002 iD8DBQFG7Eh/kn3rs5h7N1ERAk7CAKCpS/JWn89B7s5yUrv3BReOLYXE4wCeJhZp TC34AHRxwiNbHMhsY7RmGCI= =oR1U -----END PGP SIGNATURE----- --==_Exmh_1189890175_21733P--