From owner-freebsd-net@FreeBSD.ORG Tue Dec 29 07:41:49 2009 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5D5C01065676 for ; Tue, 29 Dec 2009 07:41:49 +0000 (UTC) (envelope-from hyama99@gmail.com) Received: from mail-fx0-f227.google.com (mail-fx0-f227.google.com [209.85.220.227]) by mx1.freebsd.org (Postfix) with ESMTP id DD3D08FC08 for ; Tue, 29 Dec 2009 07:41:48 +0000 (UTC) Received: by fxm27 with SMTP id 27so10617547fxm.3 for ; Mon, 28 Dec 2009 23:41:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=8nobQPadsUpKEQwf9xnPeW/fIlkN7tBqPQN/rMqnqt8=; b=qYM+0QJnjxe9f8TR7LH15HatYL/CJqEsyNsYwEwmkO4UDhPXIhz1ShV196NlySLQz0 vvAA38xLQp4XBe4u41weAucsK3WxezH8Z9rJbUgYpmF+V9WOmJrdG1wrRyUHEd7OOO45 TftQwP1CZQ7CA2YRO49xtdcAhKJNdfIqjTXe4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=ESNTUxA83n6JARQPswU52qcQAEAq3xfpw90fxIOEooHtn7ohjjcZTjXezCllu3acIc 25HT/7YgOEIWjQgvnlhKEUJzer2xM0i2ZVpwJIxRSojURXC1P/kHOtIuFLPv/LZIGIXj OfA8kDnloRQZmwK/2E730L3oVt3QO2gTJnUiY= MIME-Version: 1.0 Received: by 10.239.153.133 with SMTP id z5mr758880hbb.88.1262072500575; Mon, 28 Dec 2009 23:41:40 -0800 (PST) In-Reply-To: <4B39019C.1030705@elischer.org> References: <90dbee150912261333l602c4161nccaf1995dc83699a@mail.gmail.com> <4B3691FF.3050402@elischer.org> <90dbee150912270236k3be6e530r80d9e7576274137c@mail.gmail.com> <20091228185801.GA5508@verio.net> <4B39019C.1030705@elischer.org> Date: Tue, 29 Dec 2009 16:41:40 +0900 Message-ID: <90dbee150912282341j206505d1jd3ef13b2ff866f5f@mail.gmail.com> From: Hideki Yamamoto To: freebsd-net@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: GIF MTU parmeter is needed X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Dec 2009 07:41:49 -0000 Hi, Thank you for your information. I understand what happened in my freebsd box. As David and Julian said, "route change" command control MTU of gif, and th= e initial value is set from gif interface MTU value when "route add" command is executed. The initial value is independent from the gif interface condition, up and d= own. The following shows the result of my test: --------------------------------------------------------------------- Even after creating gif interface and getting it up, MTU value by route commamd is copied from interface MTU value when "route add" is executed. --------------------------------------------------------------------- h9# ifconfig gif5 create up h9# route add -inet6 2003:98::/64 -interface gif5 add net 2003:98::/64: gateway gif5 h9# route get -inet6 2003:98::/64 route to: 2003:98:: destination: 2003:98:: mask: ffff:ffff:ffff:ffff:: interface: gif5 flags: recvpipe sendpipe ssthresh rtt,msec mtu weight expire 0 0 0 0 1280 1 0 h9# route delete -inet6 2003:98::/64 delete net 2003:98::/64 h9# ifconfig gif5 mtu 1500 h9# route add -inet6 2003:98::/64 -interface gif5 add net 2003:98::/64: gateway gif5 h9# route get -inet6 2003:98::/64 route to: 2003:98:: destination: 2003:98:: mask: ffff:ffff:ffff:ffff:: interface: gif5 flags: recvpipe sendpipe ssthresh rtt,msec mtu weight expire 0 0 0 0 1500 1 0 h9# ifconfig gif5 inet tunnel 192.168.1.8 192.168.1.51 h9# ( ./udpgw -o -s 1500 & tshark -V -i gif5 | grep Payload ) & sleep 2 ; killall udpgw [4] 1236 [1] 1238 Let's send 1500 length packet to 2003:98::2 Capturing on gif5 Payload length: 1456 Payload length: 68 Payload length: 1456 Payload length: 68 Payload length: 1456 Payload length: 68 Payload length: 1456 Payload length: 1456 Payload length: 68 --------------------------------------------------------------------- After changing MTU from 1500 to 1300 by ifconfig command, MTU value by route commamd is changed to 1300 automatically. --------------------------------------------------------------------- h9# ifconfig gif5 mtu 1300 h9# ( ./udpgw -o -s 1500 & tshark -V -i gif5 | grep Payload ) & sleep 2 ; killall udpgw [5] 1281 [1] 1283 Let's send 1500 length packet to 2003:98::2 Capturing on gif5 Payload length: 1256 Payload length: 268 Payload length: 1256 Payload length: 268 Payload length: 1256 Payload length: 268 Payload length: 1256 Payload length: 268 Payload length: 1256 Payload length: 1256 Payload length: 268 Payload length: 1256 Payload length: 268 Payload length: 268 h9# route get -inet6 2003:98::/64 route to: 2003:98:: destination: 2003:98:: mask: ffff:ffff:ffff:ffff:: interface: gif5 flags: recvpipe sendpipe ssthresh rtt,msec mtu weight expire 0 0 0 0 1300 1 0 --------------------------------------------------------------------- However, when changing MTU from 1300 to 1500 by ifconfig command, MTU value by route command is not changed to 1500 automatically. --------------------------------------------------------------------- h9# ifconfig gif5 mtu 1500 h9# route get -inet6 2003:98::/64 route to: 2003:98:: destination: 2003:98:: mask: ffff:ffff:ffff:ffff:: interface: gif5 flags: recvpipe sendpipe ssthresh rtt,msec mtu weight expire 0 0 0 0 1300 1 0 h9# 2009/12/29 Julian Elischer : > David DeSimone wrote: >> >> Hideki Yamamoto wrote: >>> >>> =A0 =A0h99# ifconfig xl0 inet6 2001:99::1 >>> =A0 =A0h99# ifconfig gif0 create >>> =A0 =A0h99# ifconfig gif0 inet tunnel 192.168.1.8 192.168.1.4 >>> =A0 =A0h99# route add -inet6 2001:98::/64 -interface gif0 >>> =A0 =A0add net 2001:98::/64: gateway gif0 >>> =A0 =A0h99# ifconfig =A0gif0 up >> >> I wonder if the problem you're seeing is due to the MTU attached to the >> static route that you're adding rather than the MTU of the interface. >> >> Try different command sequences and perform a "route get" to find out >> what MTU is being applied to the routes, to see if they change to what >> you expect. >> > > > Actually the route mtu will over-ride the interface mtu I think.. > route change {address} mtu xxxx > > > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >