From owner-freebsd-questions@FreeBSD.ORG Wed Jul 30 07:12:46 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 27889106566B for ; Wed, 30 Jul 2008 07:12:46 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (oldagora.rdrop.com [199.26.172.34]) by mx1.freebsd.org (Postfix) with ESMTP id 0DF5A8FC08 for ; Wed, 30 Jul 2008 07:12:45 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id m6U7CgGq014118 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Wed, 30 Jul 2008 00:12:42 -0700 (PDT) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id m6U7Cg5V014117; Wed, 30 Jul 2008 00:12:42 -0700 (PDT) Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA14682; Wed, 30 Jul 08 00:09:05 PDT Date: Wed, 30 Jul 2008 00:09:45 -0700 From: perryh@pluto.rain.com To: keramida@ceid.upatras.gr Message-Id: <489013b9.Pt7+7kznBXs3SSP+%perryh@pluto.rain.com> References: <488fe865.x7NyNic2A5pcZPCL%perryh@pluto.rain.com> <87ljzkdm3x.fsf@kobe.laptop> <87hca8dlh3.fsf@kobe.laptop> In-Reply-To: <87hca8dlh3.fsf@kobe.laptop> User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: setting the other end's TCP segment size X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Jul 2008 07:12:46 -0000 > >> Is there a simple way for a FreeBSD system to cause its peer > >> to use a transmit segment size of, say, 640 bytes -- so that > >> the peer will never try to send a packet larger than that? > >> > >> I'm trying to get around a network packet-size problem. In > >> case it matters, the other end is SunOS 4.1.1 on a sun3, and > >> I've been unable to find a way to limit its packet size > >> directly. > > > > Setting the interface MTU should do it, i.e.: > > > > ifconfig re0 mtu 640 > > > > Not all interfaces support setting the MTU and some may have > > range restrictions though. > > In particular, this seems to work with my wlan0 interface, but > not with my re0 interface ... That's certainly simple enough, and xl0 apparently supports the reduced mtu setting. It seems to be working just fine. Thanks! I'd thought of trying to set the sun's MTU, but hadn't been able to find a way to do it. It had never occurred to me that setting the *recipient's* MTU would limit the *sender's* packet size.