From owner-freebsd-bugs@freebsd.org Fri Aug 23 17:32:13 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 29C9FCA84E for ; Fri, 23 Aug 2019 17:32:13 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 46FT3x0N0tz41Y2 for ; Fri, 23 Aug 2019 17:32:13 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 0C812CA84D; Fri, 23 Aug 2019 17:32:13 +0000 (UTC) Delivered-To: bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 0B345CA84C for ; Fri, 23 Aug 2019 17:32:13 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46FT3w6VGYz41Y1 for ; Fri, 23 Aug 2019 17:32:12 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id C0CC62010E for ; Fri, 23 Aug 2019 17:32:12 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x7NHWCIH049269 for ; Fri, 23 Aug 2019 17:32:12 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x7NHWCOF049268 for bugs@FreeBSD.org; Fri, 23 Aug 2019 17:32:12 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 240059] Min MTU for a interface GIF interface is to high Date: Fri, 23 Aug 2019 17:32:12 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 12.0-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: sirl33tname@gmail.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: 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: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Aug 2019 17:32:13 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D240059 Bug ID: 240059 Summary: Min MTU for a interface GIF interface is to high Product: Base System Version: 12.0-STABLE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: sirl33tname@gmail.com The Min MTU for a GIF interface is 1280. See:=20 https://github.com/freebsd/freebsd/blob/c4ed3acb9f59d3498905e95d5d445c5046f= dfdb6/sys/net/if_gif.h#L80-L82 #define GIF_MTU_MIN (1280) /* Minimum MTU */ There are some cases where this is still to high.=20 And to quote the man page: If the outer protocol is IPv6, path MTU discovery for encapsulated packets may affect communication over the interface. The first bigger- than-pmtu packet may be lost. To avoid the problem, you may want to set the interface MTU for gif to 1240 or smaller, when the outer header is IPv6 and the inner header is IPv4. So I would expect that it is possible to set the MTU for a GIF interface lo= wer than 1280. --=20 You are receiving this mail because: You are the assignee for the bug.=