From owner-freebsd-bugs@FreeBSD.ORG  Sat Feb  3 03:20:21 2007
Return-Path: <owner-freebsd-bugs@FreeBSD.ORG>
X-Original-To: freebsd-bugs@hub.freebsd.org
Delivered-To: freebsd-bugs@hub.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id CC1F716A402
	for <freebsd-bugs@hub.freebsd.org>;
	Sat,  3 Feb 2007 03:20:20 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org [69.147.83.40])
	by mx1.freebsd.org (Postfix) with ESMTP id B337713C48D
	for <freebsd-bugs@hub.freebsd.org>;
	Sat,  3 Feb 2007 03:20:20 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1])
	by freefall.freebsd.org (8.13.4/8.13.4) with ESMTP id l133KKcE073975
	for <freebsd-bugs@freefall.freebsd.org>; Sat, 3 Feb 2007 03:20:20 GMT
	(envelope-from gnats@freefall.freebsd.org)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.13.4/8.13.4/Submit) id l133KKC9073974;
	Sat, 3 Feb 2007 03:20:20 GMT (envelope-from gnats)
Date: Sat, 3 Feb 2007 03:20:20 GMT
Message-Id: <200702030320.l133KKC9073974@freefall.freebsd.org>
To: freebsd-bugs@FreeBSD.org
From: Bruce M Simpson <bms@incunabulum.net>
Cc: 
Subject: Re: bin/103762: some tun interfaces with a mtu of 1500 while i
 should never exceed 1472 with ppp
X-BeenThere: freebsd-bugs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Bruce M Simpson <bms@incunabulum.net>
List-Id: Bug reports <freebsd-bugs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-bugs>
List-Post: <mailto:freebsd-bugs@freebsd.org>
List-Help: <mailto:freebsd-bugs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 03 Feb 2007 03:20:21 -0000

The following reply was made to PR bin/103762; it has been noted by GNATS.

From: Bruce M Simpson <bms@incunabulum.net>
To: freebsd-gnats-submit@FreeBSD.org
Cc: Dominic Blais <dblais@interplex.ca>
Subject: Re: bin/103762: some tun interfaces with a mtu of 1500 while i should
 never exceed 1472 with ppp
Date: Sat, 03 Feb 2007 03:19:50 +0000

 Hi,
 
 I'm a FreeBSD committer looking into this PR.
 Not having access to your network infrastructure, I can't really 
 reproduce the problem.
 
 This does not appear to be a tun(4) problem, however; it should simply 
 do what it's told via the TUNSIFINFO ioctl or SIOCSIFMTU interface ioctl.
 
 It sounds like you're using pppoed(8) to serve PPPoE sessions. It relies 
 on Netgraph to do the low-level plumbing, then forks ppp(8) to handle 
 the PPP session itself.
 
 I would draw your attention to the following in the ppp(8) man page:
 
          set mru [max[imum]] [value]
              The default MRU (Maximum Receive Unit) is 1500.  If it is
              increased, the other side *may* increase its MTU.  In theory
              there is no point in decreasing the MRU to below the default as
              the PPP protocol says implementations *must* be able to accept
              packets of at least 1500 octets.
 
 It's entirely possible there's a bug in ppp(8) and its MRU/MTU 
 negotiation, however I lack the time and resources to track that down.
 
 Perhaps try using mpd from ports instead?
 
 Regards,
 BMS