From owner-freebsd-questions@freebsd.org Sun Jun 27 02:02:43 2021 Return-Path: Delivered-To: freebsd-questions@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 6269465DFFF for ; Sun, 27 Jun 2021 02:02:43 +0000 (UTC) (envelope-from louisk@cryptomonkeys.org) Received: from helm.louiskowolowski.com (helm.louiskowolowski.com [54.191.250.17]) (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 4GCDXL08zNz4dGR for ; Sun, 27 Jun 2021 02:02:41 +0000 (UTC) (envelope-from louisk@cryptomonkeys.org) From: Louis Kowolowski Message-Id: Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Subject: Re: IPv6 Sub Nets Date: Sat, 26 Jun 2021 21:02:35 -0500 In-Reply-To: <056639D1-32A2-4DAF-A6F8-C8743F691EAD@sermon-archive.info> Cc: FreeBSD Questions To: Doug Hardie References: <056639D1-32A2-4DAF-A6F8-C8743F691EAD@sermon-archive.info> X-Mailer: Apple Mail (2.3608.120.23.2.7) X-Rspamd-Queue-Id: 4GCDXL08zNz4dGR X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.60 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[cryptomonkeys.org:s=mail]; FROM_HAS_DN(0.00)[]; MV_CASE(0.50)[]; R_SPF_ALLOW(-0.20)[+ip4:54.191.250.17]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; NEURAL_HAM_LONG(-1.00)[-1.000]; DWL_DNSWL_LOW(-1.00)[cryptomonkeys.org:dkim]; SPAMHAUS_ZRD(0.00)[54.191.250.17:from:127.0.2.255]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[cryptomonkeys.org:+]; RCPT_COUNT_TWO(0.00)[2]; DMARC_POLICY_ALLOW(-0.50)[cryptomonkeys.org,reject]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCVD_COUNT_ZERO(0.00)[0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; RBL_DBL_DONT_QUERY_IPS(0.00)[54.191.250.17:from]; ASN(0.00)[asn:16509, ipnet:54.191.0.0/16, country:US]; MID_RHS_MATCH_FROM(0.00)[]; MAILMAN_DEST(0.00)[freebsd-questions]; RCVD_IN_DNSWL_LOW(-0.10)[54.191.250.17:from] X-Mailman-Approved-At: Sun, 27 Jun 2021 05:01:29 +0000 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.34 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 27 Jun 2021 02:02:43 -0000 On Jun 26, 2021, at 8:25 PM, Doug Hardie wrote: >=20 > I am trying to setup an IPv6 environment. There is a primary router = (A) that receives a /48 prefix via DHCP6 from the ISP. That router = configures itself properly via dhcp6c. It also creates 2 LAN /64 = prefixes and creates EUI-64 addresses on the two LAN interfaces. One of = those interfaces is connected to a second router (B), among other = devices. The B router receives the prefix via SLAAC and creates its own = EUI-64 address. However, that router needs to create a smaller subnet, = /72, and distribute it to the devices on that LAN. I have not been able = to figure out how to make that happen. =20 >=20 > Clearly, manual configuration would work, but the prefix received from = the ISP can change which would raise havoc with the network. I suspect = that dhcp6s needto be run alongside dhcp6c on router B and then the = other devices run dhcp6c. However, I don't see how to get the prefix = that dhcp6c receives on router B to the dhcp6s process on router B. I = believe I am missing something, but haven't been able to find it. = Thanks, >=20 Speaking generally First: I believe you=E2=80=99re looking to do DHCP prefix delegation = (dhcp-pd) where you designate a prefix to be used further down the line. Second: There are valid use cases for prefixes smaller than /64, but = they are not best practice, and you will likely find software that = doesn=E2=80=99t work for them (examples I=E2=80=99ve found include PDUs = hardcoding /64, dhcp not working on prefixes smaller than /64. examples = of things I=E2=80=99ve seen that do work: point-to-point links on = network equipment using /126 or /127). -- Louis Kowolowski louisk@cryptomonkeys.org = Cryptomonkeys: = http://www.cryptomonkeys.com/ Making life more interesting for people since 1977