From owner-freebsd-net@freebsd.org Fri Feb 19 02:40:53 2021 Return-Path: Delivered-To: freebsd-net@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 A5791538556 for ; Fri, 19 Feb 2021 02:40:53 +0000 (UTC) (envelope-from bc979@lafn.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 4DhbRT3bZ2z4lMn for ; Fri, 19 Feb 2021 02:40:53 +0000 (UTC) (envelope-from bc979@lafn.org) Received: by mailman.nyi.freebsd.org (Postfix) id 7B6A05387F5; Fri, 19 Feb 2021 02:40:53 +0000 (UTC) Delivered-To: net@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 7B32E53892A for ; Fri, 19 Feb 2021 02:40:53 +0000 (UTC) (envelope-from bc979@lafn.org) Received: from mail.sermon-archive.info (sermon-archive.info [71.177.216.148]) by mx1.freebsd.org (Postfix) with ESMTP id 4DhbRS6spbz4lNt for ; Fri, 19 Feb 2021 02:40:52 +0000 (UTC) (envelope-from bc979@lafn.org) Received: from [10.0.1.251] (mini [10.0.1.251]) by mail.sermon-archive.info (Postfix) with ESMTPSA id 4DhbRR6YDSz2fjQy for ; Thu, 18 Feb 2021 18:40:51 -0800 (PST) From: Doug Hardie Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.60.0.2.21\)) Subject: IPv6 DAD Message-Id: <1AFA2FDE-F382-4EAC-9424-E03570566125@sermon-archive.info> Date: Thu, 18 Feb 2021 18:40:51 -0800 To: "net@freebsd.org" X-Mailer: Apple Mail (2.3654.60.0.2.21) X-Virus-Scanned: clamav-milter 0.103.0 at mail X-Virus-Status: Clean X-Rspamd-Queue-Id: 4DhbRS6spbz4lNt X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of bc979@lafn.org designates 71.177.216.148 as permitted sender) smtp.mailfrom=bc979@lafn.org X-Spamd-Result: default: False [-2.69 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FROM_HAS_DN(0.00)[]; RBL_DBL_DONT_QUERY_IPS(0.00)[71.177.216.148:from]; R_SPF_ALLOW(-0.20)[+ip4:71.177.216.148/32:c]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[net@freebsd.org]; DMARC_NA(0.00)[lafn.org: no valid DMARC record]; RCPT_COUNT_ONE(0.00)[1]; SPAMHAUS_ZRD(0.00)[71.177.216.148:from:127.0.2.255]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.99)[-0.993]; TO_DN_EQ_ADDR_ALL(0.00)[]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:5650, ipnet:71.177.216.0/23, country:US]; RCVD_COUNT_TWO(0.00)[2]; MAILMAN_DEST(0.00)[net] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Feb 2021 02:40:53 -0000 The last time I played with IPv6 (FreeBSD 9), DAD was activated when the = network was first configured. Once the interface came up, a neighbor = solicitation was sent with the link-local address to see if it = duplicated anywhere else. Trying that with FreeBSD 13.0-BETA2 it is = quite different. Bringing up an interface does not result in and = solicitations. The MAC based address is just used. If you bring up = another machine with that address, the neighbor solicitation is send and = a response is received. However, the address is still entered as shown = in ndp. There is no attempt to pick a different address. However, = ifconfig now shows duplicated: inet6 fe80::250%bge0 prefixlen 64 duplicated scopeid 0x1 That address on the first machine to have it continues to work and is = accessible from a third machine. I used quite arbitrary addresses for this experiment. =20 I noticed there was a significant update to the RFCs on DAD so I suspect = this behavior is now desired, but it is not obvious. =20 -- Doug