From owner-cvs-sys  Wed Dec  4 10:12:34 1996
Return-Path: owner-cvs-sys
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.5/8.7.3) id KAA13654
          for cvs-sys-outgoing; Wed, 4 Dec 1996 10:12:34 -0800 (PST)
Received: from who.cdrom.com (who.cdrom.com [204.216.27.3])
          by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id KAA13645;
          Wed, 4 Dec 1996 10:12:32 -0800 (PST)
Received: from alpha.xerox.com (alpha.Xerox.COM [13.1.64.93])
          by who.cdrom.com (8.7.5/8.6.11) with SMTP id KAA00291
          ; Wed, 4 Dec 1996 10:12:29 -0800 (PST)
Received: from crevenia.parc.xerox.com ([13.2.116.11]) by alpha.xerox.com with SMTP id <16403(5)>; Wed, 4 Dec 1996 10:10:40 PST
Received: from localhost ([127.0.0.1]) by crevenia.parc.xerox.com with SMTP id <177711>; Wed, 4 Dec 1996 10:10:26 -0800
X-Mailer: exmh version 1.6.7 5/3/96
To: Poul-Henning Kamp <phk@freefall.freebsd.org>
cc: CVS-committers@freefall.freebsd.org, cvs-all@freefall.freebsd.org,
        cvs-sys@freefall.freebsd.org
Subject: Re: cvs commit: src/sys/net if_tun.h 
In-reply-to: Your message of "Tue, 03 Dec 1996 07:49:25 PST."
             <199612031549.HAA23417@freefall.freebsd.org> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Wed, 4 Dec 1996 10:10:21 PST
From: Bill Fenner <fenner@parc.xerox.com>
Message-Id: <96Dec4.101026pst.177711@crevenia.parc.xerox.com>
Sender: owner-cvs-sys@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

In message <199612031549.HAA23417@freefall.freebsd.org>you write:
>  Branch:      sys/net   RELENG_2_2
>  Modified:    sys/net   if_tun.h

I'm a little uncomfortable with this; merging a default-tunnel-device-MTU-change into 2.2 without any testing outside of whistle probably has more implications than we want.  Notably, peoples' ppp connections are going to start out with an interface MTU of 1600, where most paths on the Internet have an MTU of 1500.  This will exercise the PMTU discovery code a lot more and is probably not something we want to do without testing in -current for longer.

I'd like to change the default back to 1500, and modify if_tun.c so that it respects the MTU of the interface instead of using the constant.  That way, applications can set the MTU with TUNSIFINFO or SIOCSIFMTU and get whatever MTU they want, and the default stays a conservative 1500.

  Bill