From owner-freebsd-questions@freebsd.org Sun Jun 27 16:36:48 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 BF3A7645AE5 for ; Sun, 27 Jun 2021 16:36:48 +0000 (UTC) (envelope-from kurt.buff@gmail.com) Received: from mail-ej1-x62b.google.com (mail-ej1-x62b.google.com [IPv6:2a00:1450:4864:20::62b]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4GCbwv4SlBz4cym for ; Sun, 27 Jun 2021 16:36:47 +0000 (UTC) (envelope-from kurt.buff@gmail.com) Received: by mail-ej1-x62b.google.com with SMTP id bg14so24825674ejb.9 for ; Sun, 27 Jun 2021 09:36:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Jdh4rNgv+LYCgHyeBVGKsn1vNHBI0xmiGJ1Fl/+AqwE=; b=DT3FsjU/0EsnWfY0qo9pDgjZHDhD3RtTnkIlrSmJ2REt4ncr7GWFyZngf9eLlhELpp qhsFQjR91+v2W/qqybc736qUojM0rntZHHeTy6OkYImBqr3aO220pwtZvbtJlAqgK2Na 6WWM20K8zve5dztQo93sjG54KmVbCx0jsaaNRiG1lpnQpQkdLmuRfJOZcr4wA3vAoTu2 2EkcfcapmmKsFCPvFoGA83WnjosSE+9cWK5XAxqWH0OjDRo1VWHJICmubhQKgCN3nlu4 x9eLimvHaf4n1kGLqouQTWxTaS/JLdNbCZSAjchUCPkg4FpGudIW5rSVKT45M9rzeo9e SLZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Jdh4rNgv+LYCgHyeBVGKsn1vNHBI0xmiGJ1Fl/+AqwE=; b=mxMqXsq3y+/1InCr/fpDHvqt56N9/IVcj6C1E6/ZFSXidcLN19zgYiemrPAYeg/2Vw G6jHboYDggyLRa64hCfgtVniqKmT1wdJVN9TKJR5nLpwaiBPio1fre622XF17ichWckF rNo3uACU29BLs4y68R48HuADrDYgBHoVDDXNpO2oKKs2OorNaP04LD4qJupCUp0NzkDJ WY8zo+hgqK2THErBBwck5H9p4gyWcGsDfwLjIhh/CXUabgbCCPc438FkDoTXHRs+GGti q9Z/5NVrcoBR03u3N/jZG/NetH2a91V0LRJxiG/+4K46PAIcsWWMriGoHsJ2GwSG0Hmk Zo+Q== X-Gm-Message-State: AOAM531PuKb0s375VqucQsm9wncdjh1CUJJBNxXejPQ3+Euu2uQ2jHWx rCGG4e9HeqcgM/0IX/tXLn5NZ8Sm2QSItu4SuNk= X-Google-Smtp-Source: ABdhPJyrV/oZ6Qo90ryeLyyJnvvxrOvP1nzIhorQaini6FEhwcjg40HU91Qw5czlPE9RufpZY/zOJ9d+K9a3EQY3P94= X-Received: by 2002:a17:906:52d6:: with SMTP id w22mr20649359ejn.512.1624811805685; Sun, 27 Jun 2021 09:36:45 -0700 (PDT) MIME-Version: 1.0 References: <056639D1-32A2-4DAF-A6F8-C8743F691EAD@sermon-archive.info> <5B552F4B-0BA3-4962-A131-AB352A88980C@sermon-archive.info> In-Reply-To: <5B552F4B-0BA3-4962-A131-AB352A88980C@sermon-archive.info> From: Kurt Buff Date: Sun, 27 Jun 2021 10:36:33 -0600 Message-ID: Subject: Re: IPv6 Sub Nets To: Doug Hardie Cc: FreeBSD Questions Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 4GCbwv4SlBz4cym X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=DT3FsjU/; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of kurtbuff@gmail.com designates 2a00:1450:4864:20::62b as permitted sender) smtp.mailfrom=kurtbuff@gmail.com X-Spamd-Result: default: False [-2.00 / 15.00]; FREEMAIL_FROM(0.00)[gmail.com]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RBL_DBL_DONT_QUERY_IPS(0.00)[2a00:1450:4864:20::62b:from]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; TAGGED_FROM(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; NEURAL_SPAM_SHORT(1.00)[1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-questions@freebsd.org]; SPAMHAUS_ZRD(0.00)[2a00:1450:4864:20::62b:from:127.0.2.255]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::62b:from]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[freebsd-questions] 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 16:36:48 -0000 On Sat, Jun 26, 2021 at 8:19 PM Doug Hardie wrote: > > > -- Doug > > > On 26 June 2021, at 19:02, Louis Kowolowski = wrote: > > > > On Jun 26, 2021, at 8:25 PM, Doug Hardie > wrote: > >> > >> 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 configur= es itself properly via dhcp6c. It also creates 2 LAN /64 prefixes and crea= tes 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 recei= ves 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 dev= ices on that LAN. I have not been able to figure out how to make that happ= en. > >> > >> Clearly, manual configuration would work, but the prefix received from= the ISP can change which would raise havoc with the network. I suspect th= at dhcp6s needto be run alongside dhcp6c on router B and then the other dev= ices run dhcp6c. However, I don't see how to get the prefix that dhcp6c re= ceives on router B to the dhcp6s process on router B. I believe I am missi= ng something, but haven't been able to find it. Thanks, > >> > > Speaking generally > > > > First: I believe you=E2=80=99re looking to do DHCP prefix delegation (d= hcp-pd) where you designate a prefix to be used further down the line. > > That is what is being used between the ISP and router A. However, router= Bs dhcp6s needs to find that prefix. About all I have come up with is som= e sort of script which monitors the network addresses and then updates dhcp= 6s.conf and restarts dhcp6s. Not very elegant though. > > > Second: There are valid use cases for prefixes smaller than /64, but th= ey 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.or= g > > Cryptomonkeys: http://www.cryptomonke= ys.com/ On one of the ipv6 lists to which I subscribe (ipv6-ops), there have been discussions of renumbering by ISP and the difficulties it's posing. I don't have a link handy, and I don't think the discussion reached a conclusion, but you might glean some useful insights from it. Kurt