From owner-freebsd-bugs@freebsd.org Fri Jan 29 03:35:08 2016 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6E57DA71CAD for ; Fri, 29 Jan 2016 03:35:08 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 45BC61118 for ; Fri, 29 Jan 2016 03:35:08 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id u0T3Z8KG034151 for ; Fri, 29 Jan 2016 03:35:08 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 206721] FreeBSDs DHCP client(dhclient) does not support the interface-mtu option(option 26). Date: Fri, 29 Jan 2016 03:35:08 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: 11.0-CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: jlpetz@gmail.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 Jan 2016 03:35:08 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206721 Bug ID: 206721 Summary: FreeBSDs DHCP client(dhclient) does not support the interface-mtu option(option 26). Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: bin Assignee: freebsd-bugs@FreeBSD.org Reporter: jlpetz@gmail.com After getting the Intel ixv driver working for AWS instances. I noticed the= re was some severe packet loss in iPerf tests. Looking at ifconfig I suspected there was an MTU blackhole between the virtual ethernet interface(ixv) with= MTU of 1500 and the physical card MTU 9001. Confirmed by manually changing it a= nd a few ping tests with 'Don't fragment' flags set. Changing the MTU manually corrected the packet loss. But then I was wonderi= ng why this wasn't automatically done like it is for other operating systems w= hich I have run on AWS EC2. Turn out it looks like EC2 sends the MTU which should be configured for the interface as part of the DHCP response and FreeBSDs default client. 1. Doesn't request the interface-mtu option(option 26). Needed for it to be= in the response 2. Even if it did request it this option and got it in the response. I don't think it would process it and configure the MTU on the NIC. Based on the so= urce code I looked at. I was able to work around this by using the isc-dhcp43-client-4.3.3 package/port. But am logging this as a bug/feature-request as I feel this should be part of the base system. MTU blackholes are quite common when usi= ng jumbo frame(~9000 MTU) systems and this seems like a good way of avoiding t= hem which a lot of other operating systems are doing by default. More details about this are in the phabricator review which has my testing details(Link below). Make sure you click on the "Show Older Changes" to see= all the text on the page below. https://reviews.freebsd.org/D4788 --=20 You are receiving this mail because: You are the assignee for the bug.=