From owner-freebsd-questions Sun Sep 16 22:40:25 2001 Delivered-To: freebsd-questions@freebsd.org Received: from mta2-rme.xtra.co.nz (mta2-rme.xtra.co.nz [203.96.92.3]) by hub.freebsd.org (Postfix) with ESMTP id 94B9C37B411 for ; Sun, 16 Sep 2001 22:40:21 -0700 (PDT) Received: from development.wgtn.csg.co.nz ([210.86.1.68]) by mta2-rme.xtra.co.nz with SMTP id <20010917054020.BVUZ2668682.mta2-rme.xtra.co.nz@development.wgtn.csg.co.nz> for ; Mon, 17 Sep 2001 17:40:20 +1200 Content-Type: text/plain; charset="iso-8859-1" From: David Preece Reply-To: davep@afterswish.com To: freebsd-questions@freebsd.org Subject: MTU table? Date: Mon, 17 Sep 2001 17:40:35 +1200 X-Mailer: KMail [version 1.2] MIME-Version: 1.0 Message-Id: <01091717403513.83234@development.wgtn.csg.co.nz> Content-Transfer-Encoding: 8bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Hi, I have a network consisting of: Server (mtu1500)<->(mtu1500)gateway(mtu576)<->Client (mtu1500) The server and gateway are both FreeBSD4.x machines and the client is NT4, hence changing MTU is a bit of a mystery, but I digress. So, the first time the client connects to the server and the server attempts to send back a packet of over 576 bytes, the gateway objects and sends back an ICMP 3(4) saying that the packet can't be forwarded until the MTU is reduced to 576. The server tries again with the new MTU and all is well. The kernel on the server also has the good sense to remember that there's an MTU of 576 bytes on that route and doesn't try anything larger in future. This would be great *except* that I'm trying to turn the whole thing into a factory for ICMP cannot fragment messages. Is there a simple way to flush the route->mtu table on the server? Thanks, Dave To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message