Date: Wed, 14 Dec 2011 09:41:51 +0900 (JST) From: Hiroki Sato <hrs@FreeBSD.org> To: mrossi@swin.edu.au Cc: doconnor@gsoft.com.au, freebsd-net@FreeBSD.org Subject: Re: FreeBSD 8 as an IPv6 router Message-ID: <20111214.094151.1901872428047005963.hrs@allbsd.org> In-Reply-To: <4EE7CDBE.1090605@swin.edu.au> References: <58FFF22D-6578-447D-AAC0-9673057DAD84@gsoft.com.au> <yge39co5rk4.wl%ume@mahoroba.org> <4EE7CDBE.1090605@swin.edu.au>
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----Security_Multipart(Wed_Dec_14_09_41_51_2011_589)-- Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mattia Rossi <mrossi@swin.edu.au> wrote in <4EE7CDBE.1090605@swin.edu.au>: mr> Ok, this is something I always get a bit confused with. I understand mr> that it's the right clean thing to set up a /64 on the interface which mr> sends router advertisements, but I also would expect by nature, that mr> whatever prefixlength you chose on the interface, rtadvd would simply mr> grab the lowest /64 prefix out of the configured one to send router mr> advertisements out. mr> mr> The idea there is, that you might use this router for multiple mr> subnets, and have a single default route. mr> mr> Now of course to do that you'd need to configure rtadvd.conf, so I mr> guess the whole thing missing here is a bit of documentation which mr> says, that if you don't configure rtadvd via rtadvd.conf you're not mr> allowed to be lazy and configure any prefix on the interface and mr> expect rtadvd to do the right thing. mr> mr> It seems to me, that a lot of people (including me) would expect that, mr> so maybe some info about that wouldn't be to bad. I do not think it is a good idea that the rtadvd daemon automatically splits prefixes shorter than 64 to ones with just 64. "Which prefix should be advertised" is one of things which a sysadmin must specify explicitly when it receives prefixes shorter than 64 via IA-PD or something, and it should match the actual subnet structure. A simple way to do so is to assign an address onto eth0, in his example, with desired /64 subnet prefix from the delegated (shorter) prefix, and run rtadvd with no configuration file. This is the expected scenario. A /60 address assigned on eth0 does not work as a default router address for multiple /64 subnets anyway... This trouble is caused by misconfiguration of sla-len and non-/64 prefix is assigned unexpectedly to eth0. If all of the configuration were correct rtadvd.conf was not needed in the first place, and even if split /64 prefixes were automatically advertised by rtadvd at that time the situation would not got better. -- Hiroki ----Security_Multipart(Wed_Dec_14_09_41_51_2011_589)-- Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEABECAAYFAk7n8M8ACgkQTyzT2CeTzy3yxACg1g296S7W3Tjdt/zo77vN9kt1 DngAoJBPU2Qhb4gSW61sW+Nh933gGb2/ =ai9n -----END PGP SIGNATURE----- ----Security_Multipart(Wed_Dec_14_09_41_51_2011_589)----
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