From owner-freebsd-questions Sat May 11 18:58:21 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id SAA11665 for questions-outgoing; Sat, 11 May 1996 18:58:21 -0700 (PDT) Received: from uucp.tip.net ([194.16.0.15]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id SAA11660 for ; Sat, 11 May 1996 18:58:18 -0700 (PDT) Received: from icon.pp.se (uucp@localhost) by uucp.tip.net (8.6.12/8.6.5) with UUCP id DAA11276 for freebsd-questions@freebsd.org; Sun, 12 May 1996 03:58:10 +0200 Received: (from daniel@localhost) by icon.pp.se (8.7.5/8.7.3) id DAA03958; Sun, 12 May 1996 03:20:28 +0200 (MET DST) Date: Sun, 12 May 1996 03:20:28 +0200 (MET DST) Message-Id: <199605120120.DAA03958@icon.pp.se> From: Daniel Eriksson To: freebsd-questions@freebsd.org Subject: Setting MTU on tun0 Sender: owner-questions@freebsd.org X-Loop: FreeBSD.org Precedence: bulk I'm using user-mode PPP (iijpp) to connect to my provider over a 28k8-modem (USR Courier) connected to the computer via a 16550A on an ISA-card. I'v tried both 2.1-STABLE and 2.2-CURRENT (latest SNAP) and the symptoms are the same. The problem is poor performance when sending data. It's close to impossible to get any kind of data out from the computer. Downloading data work good though (3k/sec FTP). I'm no expert, but AFAIK I've got 2 major sources to look at for the error: * Computer<->modem (RTS/CTS) * MTU-size I asked a similar question a couple of months back and was told that I only needed to recompile /sys/net/if_tun.h with a different setting for TUNMTU. However, whatever I do I still end up with a MTU of 1500 (as reported by netstat -i). How do I force iijpp to use an MTU of 552? I've tried changing every occourance of 1500 in /sys/net/ without success. :-( Do I need to do anything special in order to get RTS/CTS to work? Must I edit rc.serial, or are they enabled by default? -- Daniel Eriksson, daniel@icon.pp.se