From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from MAIL1.WPI.EDU (MAIL1.WPI.EDU [130.215.36.91]) by huchra.bufferbloat.net (Postfix) with ESMTP id 8ECCC21F214 for ; Wed, 26 Nov 2014 19:21:17 -0800 (PST) Received: from MAIL1.WPI.EDU (MAIL1.WPI.EDU [130.215.36.91]) by MAIL1.WPI.EDU (8.15.1.Beta2/8.15.1.Beta2) with ESMTP id sAR3LGhv015464 for ; Wed, 26 Nov 2014 22:21:16 -0500 X-DKIM: Sendmail DKIM Filter v2.8.3 MAIL1.WPI.EDU sAR3LGhv015464 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=wpi.edu; s=_dkim; t=1417058476; bh=dx7XkpB+tIJzEMGglsSzpOlHs9ZDkG4ChKh2ZGbsbtA=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:In-Reply-To; b=DvBdZT9HkLK0PSqkItNLx5g7KrEVtqQNkOKS9pCw6sTlpFq0LfigX9vlyGZwf3e6w xgTZDNepmLEkE5Qcf1vUg1+anuzeszAvkuMZgfbltzV0GdrN5Qkt/DZcuk4zNDgd4h /OlAFtHdW53XuBBDAWYdafvaIC7B64/9MR/TxjOI= Received: from MX3.WPI.EDU (mx3.wpi.edu [130.215.36.147]) by MAIL1.WPI.EDU (8.15.1.Beta2/8.15.1.Beta2) with ESMTP id sAR3LG7n015458 for ; Wed, 26 Nov 2014 22:21:16 -0500 Received: from angus.ind.WPI.EDU (ANGUS.IND.WPI.EDU [130.215.130.21]) by MX3.WPI.EDU (8.14.4/8.14.4) with ESMTP id sAR3LFgX030221 for ; Wed, 26 Nov 2014 22:21:16 -0500 (envelope-from cra@WPI.EDU) Received: from angus.ind.WPI.EDU (localhost [127.0.0.1]) by angus.ind.WPI.EDU (8.14.4/8.14.4) with ESMTP id sAR3LFI0018406 for ; Wed, 26 Nov 2014 22:21:15 -0500 Received: (from cra@localhost) by angus.ind.WPI.EDU (8.14.4/8.14.4/Submit) id sAR3LE7c018405 for cerowrt-devel@lists.bufferbloat.net; Wed, 26 Nov 2014 22:21:14 -0500 X-Authentication-Warning: angus.ind.WPI.EDU: cra set sender to cra@WPI.EDU using -f Date: Wed, 26 Nov 2014 22:21:14 -0500 From: Chuck Anderson To: cerowrt-devel@lists.bufferbloat.net Message-ID: <20141127032113.GP16805@angus.ind.WPI.EDU> Mail-Followup-To: cerowrt-devel@lists.bufferbloat.net References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-12-10) Subject: Re: [Cerowrt-devel] ipv6 confusion with source specific gateways. X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Nov 2014 03:21:47 -0000 On Tue, Nov 25, 2014 at 11:11:17PM -0800, Dave Taht wrote: > Some days I just lose it with prefix math. Or maybe we have a bug. Prefix math, there is no bug. > So here is a default gateway. So far as I know it is getting a /56 > actually, not a /60, but it is requesting a /60 and thus distributing > a source specific route to that /60. Looks like a /60. > default from :: via fe80::201:5cff:ee62:b646 dev ge00 proto static metric 1024 > # should I even have a default route at all? > default from 2001:558:6045:e9:44a9:4a25:ece9:55c3 via > fe80::201:5cff:ee62:b646 dev ge00 proto static metric 1024 > # my uplink, looks sane > > default from 2601:c:ce00:9d0::/60 via fe80::201:5cff:ee62:b646 dev > ge00 proto static metric 1024 > # and see that /60... > > # and then there is the default ipv6 address assignements on cero. > > 2601:c:ce00:9d1::/64 dev gw10 proto kernel metric 256 expires 326362sec > > Now, where my brain crashes: shouldn't 2601:c:ce00:9d1::/64 actually > be something like > > 2601:c:ce00:9d01::/64 not, 2601:c:ce00:9d1::/64? No, it is correct. The /60 is: 2601:c:ce00:9d0::/60 which is really this when expanded out (zero-pad each : section): 2601:000c:ce00:09d0::/60 Now the 60 bit prefix is: 2601:000c:ce00:09dX:XXXX:XXXX:XXXX:XXXX where X is the part which can be assigned to your LANs. The first X is a 4-bit nibble that was assigned "1" by Cero creating a /64 subnet prefix, leaving the remaining 64 bits for your Interface IDs...