From nobody Wed Nov 16 03:19:06 2022 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4NBpDk4Vb3z4hNFG for ; Wed, 16 Nov 2022 03:19:18 +0000 (UTC) (envelope-from zlei@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4NBpDk3cx9z4Gjv; Wed, 16 Nov 2022 03:19:18 +0000 (UTC) (envelope-from zlei@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1668568758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VocK45kmod42+7i9JIJZMuLJu/glffxKJEUGYRpZsZQ=; b=VLbviMlu3qm2KcQ1JXooSXvhoJ0GH3k9GdDbL3v8BdQp1JYZhJGRoEM8KR574jWqcpVw+I WJ1mcQd2OlWCCK7+AUwghahuT6hX7OUN9mw0xiN9PRLmY9ysRDhuk8EXq9RwfYyGdvZx3V x9Rd5jE71aa2kBER5XjBr+bs77szoH/sGcvbtWo0zlMWa0VAtD8HHPnydCvlDEvq2bF4JU +viyNWpO/gIjiKx5XKCrn7zaKh1KuBJR/UVcNEz395PjiRaqXxHoFa4oWlLU6jZTrrBsDO Lq2o6E1XlHq+FrFzoEOX1nUZJpL4CRE/2jgaPhJqMOtXROREHwXouqWDezIYZQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1668568758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VocK45kmod42+7i9JIJZMuLJu/glffxKJEUGYRpZsZQ=; b=qPsQk+eOjow4U0EGMuUxOyeMYPJUA9RIvxq95oSwhHVxGeu2o+/SqIubauyKrJRFCOWOkc xGDCAM4ymE8HeqHlVRrDcb2zBIRbzH4djN47lzVRyUKh4vMmvTWtj4JWZsQU0NjDI/OCAS S7vX/QHCgQ7NJSSUU66L/J0OMJYBybzhsWPOvwA3X14DNqATX7wQnoPf7tVZcZoHyfsRHH Zz63kSFjX25aLmV4zLp9g7RFvXtWXP0ef0ZnmrNSIIc7+iI9XSxr8Fu/Ji6AR3uqWg2G+1 DnlcqJweEtuY509uLSpRSAa+NpuyimBZu1ydoOpYO4U6/4gC7Z9EAECzdhpzSg== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1668568758; a=rsa-sha256; cv=none; b=d1c8GgKLWPmRgqUnCJ1rjgjRZ5gopjMLHDwULuayvmJOmocWUD/atUpx1nrJKGQptiiAeV 6uYsObYWUAEJ4FhC4pf0PHq8Le4D5N3NSL2xHx20lTpp48dgf0W2N7ZxI2FOLGaxddDHMm m05fcAwvZIEfYbxnsXi+c3sOhuF20440wsWVwrcvxbF41dP/UfAFIEMXXeqTrwCAF+STH3 PTgj0CcK9RClypXvjFL0v2iNpjg6VDAl78wQMWNHhRYavwfjpE04Qw9qrxfaj/KblGpltU e0Rxy46YSweDDy3zwSP+VXebCLmfltuk9QhOZix2VXsQ/p/vz7S7oeZLN5QxZQ== Received: from [IPv6:fd03:a1b3:1819::8001] (unknown [IPv6:2001:19f0:6001:9db:98f0:9fe0:3545:10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) (Authenticated sender: zlei/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 4NBpDj2tRhzq5c; Wed, 16 Nov 2022 03:19:17 +0000 (UTC) (envelope-from zlei@FreeBSD.org) Content-Type: text/plain; charset=us-ascii List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Subject: Re: ICMPv6 over lo0 From: Zhenlei Huang In-Reply-To: Date: Wed, 16 Nov 2022 11:19:06 +0800 Cc: freebsd-net Content-Transfer-Encoding: quoted-printable Message-Id: References: To: tuexen@freebsd.org X-Mailer: Apple Mail (2.3608.120.23.2.7) X-ThisMailContainsUnwantedMimeParts: N > On Nov 16, 2022, at 5:14 AM, tuexen@freebsd.org wrote: >=20 > Dear all, >=20 > when using the master branch of today (or 13.1) I get when running >=20 > tuexen@ampere128:~ % ping6 -c 1 -b 30000 -s 20000 ::1 > PING6(20048=3D40+8+20000 bytes) ::1 --> ::1 > 20008 bytes from ::1, icmp_seq=3D0 hlim=3D64 time=3D0.709 ms >=20 > --- ::1 ping6 statistics --- > 1 packets transmitted, 1 packets received, 0.0% packet loss > round-trip min/avg/max/std-dev =3D 0.709/0.709/0.709/0.000 ms >=20 > which is expected. What I don't expect is: >=20 > tuexen@ampere128:~ % tcpdump -i lo0 -n > tcpdump: verbose output suppressed, use -v or -vv for full protocol = decode > listening on lo0, link-type NULL (BSD loopback), capture size 262144 = bytes > 22:06:38.835630 IP6 ::1 > ::1: frag (0|1232) ICMP6, echo request, seq = 0, length 1232 > 22:06:38.835639 IP6 ::1 > ::1: frag (1232|1232) > 22:06:38.835641 IP6 ::1 > ::1: frag (2464|1232) > 22:06:38.835641 IP6 ::1 > ::1: frag (3696|1232) > 22:06:38.835642 IP6 ::1 > ::1: frag (4928|1232) > 22:06:38.835642 IP6 ::1 > ::1: frag (6160|1232) > 22:06:38.835643 IP6 ::1 > ::1: frag (7392|1232) > 22:06:38.835644 IP6 ::1 > ::1: frag (8624|1232) > 22:06:38.835644 IP6 ::1 > ::1: frag (9856|1232) > 22:06:38.835645 IP6 ::1 > ::1: frag (11088|1232) > 22:06:38.835645 IP6 ::1 > ::1: frag (12320|1232) > 22:06:38.835646 IP6 ::1 > ::1: frag (13552|1232) > 22:06:38.835647 IP6 ::1 > ::1: frag (14784|1232) > 22:06:38.835647 IP6 ::1 > ::1: frag (16016|1232) > 22:06:38.835648 IP6 ::1 > ::1: frag (17248|1232) > 22:06:38.835648 IP6 ::1 > ::1: frag (18480|1232) > 22:06:38.835649 IP6 ::1 > ::1: frag (19712|296) > 22:06:38.836002 IP6 ::1 > ::1: frag (0|16336) ICMP6, echo reply, seq = 0, length 16336 > 22:06:38.836006 IP6 ::1 > ::1: frag (16336|3672) > ^C > 19 packets captured > 19 packets received by filter > 0 packets dropped by kernel >=20 > Why is for the Echo Request an MTU of 1280 used, whereas for the = response an MTU of 16384 > is used. >=20 > Since > tuexen@ampere128:~ % ifconfig lo0 > lo0: flags=3D8049 metric 0 mtu 16384 > options=3D680003 > inet6 ::1 prefixlen 128 > inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3 > inet 127.0.0.1 netmask 0xff000000 > groups: lo > nd6 options=3D21 > is used, I would expect an MTU of 16384 also be used for the Echo = Request instead of > the minimum IPv6 MTU of 1280. I believe MTU of 16384 should be used for Echo Request. >=20 > Is this intended? At least for me, it is not expected... >=20 > Best regards > Michael