From owner-freebsd-net@FreeBSD.ORG Thu Feb 10 22:16:34 2011 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 9C9E7106566C for ; Thu, 10 Feb 2011 22:16:34 +0000 (UTC) (envelope-from jfvogel@gmail.com) Received: from mail-yw0-f54.google.com (mail-yw0-f54.google.com [209.85.213.54]) by mx1.freebsd.org (Postfix) with ESMTP id 5309A8FC15 for ; Thu, 10 Feb 2011 22:16:34 +0000 (UTC) Received: by ywl2 with SMTP id 2so834241ywl.13 for ; Thu, 10 Feb 2011 14:16:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=Nb8P3tHaEcvoz4bhd+X6m2rI11tAqdfd634GofBPxyk=; b=qPjgX2K7XD89RxVvH7z0cBS28kmzWbnVzErB8X9MoltHk/HLgUhXz2Uwt3mvN/qzpI NotC8k8OhQ5Fo5Ei5KPBHNLciHidfnIt8ZToppEG37UPyba0xj69r+Yp2w6U16kCayPR xQLeLWSWy7X3nn2JNuVhFZqkJMpeEVbcvKX7A= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=Xy2kcHCkJcj7Qh2cXXoWqzAB8szGIpfF+QiOCZRucvtw2D32kNyuwE57X89eJIY4tN nwXpkLorLRVe0d7us7VEXGhuaN8tzmVnoz7w5GuvIoyHMYsSXMuUUj6vGKOzW0r2+2WS dvqiqknWvC2oaEJTkaIbzMXmetp16Du1FS1aM= MIME-Version: 1.0 Received: by 10.150.148.18 with SMTP id v18mr4097422ybd.54.1297376193596; Thu, 10 Feb 2011 14:16:33 -0800 (PST) Received: by 10.147.167.5 with HTTP; Thu, 10 Feb 2011 14:16:33 -0800 (PST) In-Reply-To: <19796.24842.872566.716691@oz.mt.att.com> References: <19796.13124.805432.342309@oz.mt.att.com> <19796.24842.872566.716691@oz.mt.att.com> Date: Thu, 10 Feb 2011 14:16:33 -0800 Message-ID: From: Jack Vogel To: Jay Borkenhagen Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-net@freebsd.org, Sergey Kandaurov Subject: Re: cannot set mtu > 1500 on em0 optical Gig-E 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: Thu, 10 Feb 2011 22:16:34 -0000 Ahem, its our OLDEST 1G part, it was ancient when I took this job 5 years ago :) And the code is working according to spec, jumbos are not supported on the device, that's not the same as saying its not possible. We only have one or two of these devices laying around, and I get a chuckle any time I've asked to use one to repro something, adapters aren't that expensive, time to think about an upgrade :) Jack On Thu, Feb 10, 2011 at 2:04 PM, Jay Borkenhagen wrote: > Jack Vogel writes: > > Thanks Sergey :) > > > [...] > > > > > > Hmm.. Did jumbo frames really work on these cards for you? Intel > > > claims: "Adapters based on the Intel=AE 82542 and 82573V/E > > > controller do not support Jumbo Frames. These correspond to the > > > following product names: > > > > > > * Intel=AE PRO/1000 Gigabit Server Adapter > > > * Intel=AE PRO/1000 PM Network Connection " > > > > > > As seen from code, the behavior was changed to match the > > > description ("keep old 82542 from using jumbo frames") and merged > > > to 6-STABLE before 6.3. > > > > > > Well, I've got tcpdumps showing DF-bit-set pings succeeding to and > from such a NIC with MTU >> 1500, on a box running 6.2-RELEASE. > (pciconf data below.) In this particular case I have MTU=3D4470, which > is really good enough for what I need, and DF pings succeed up to > 'ping -s 4442' > > Maybe Intel thought they couldn't handle MTUs approaching 9k, or maybe > they had problems approaching linerate -- neither of which are > concerns in my application... > > > em0@pci0:2:0: class=3D0x020000 card=3D0x10008086 chip=3D0x10008086 rev= =3D0x03 > hdr=3D0x00 > vendor =3D 'Intel Corporation' > device =3D '82542 Gigabit Ethernet Controller' > class =3D network > subclass =3D ethernet >