Date: Fri, 19 Mar 2010 13:00:40 +1300 From: Andrew Thompson <thompsa@FreeBSD.org> To: Stefan Bethke <stb@lassitu.de> Cc: freebsd-net@freebsd.org Subject: Re: Running rtadvd or DHCPv6 server via if_bridge interface Message-ID: <20100319000040.GC45454@citylink.fud.org.nz> In-Reply-To: <EFAF0399-1809-4902-8C7E-33812D296D92@lassitu.de> References: <20091211052349.0000517a@unknown> <20091211065141.GL88840@marvin.timesinks.net> <EFAF0399-1809-4902-8C7E-33812D296D92@lassitu.de>
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On Thu, Mar 18, 2010 at 11:27:43PM +0100, Stefan Bethke wrote: > Am 11.12.2009 um 07:51 schrieb Chris Cowart: > > > Bruce Cran wrote: > >> I have a router configured using if_bridge with a 4-port NIC that's > >> serving addresses over DHCP. I'd like to add in either rtadvd or > >> DHCPv6, but neither work because the bridge interface doesn't have an > >> IPv6 link-local address. Is there a way around this, or is it not > >> possible to serve IPv6 addresses over if_bridge interfaces? > > > > It's totally doable; you just have to assigned a link-local address to > > the bridge. There are some reasons why one isn't defined by default, > > which somebody more knowledgeable about the challenges in the > > implementation can highlight. > > > > Here's my configuration from rc.conf: > > > > ipv6_ifconfig_bridge0="2001:470:8337:10::1/64" > > ipv6_ifconfig_bridge0_alias0="fe80::2%bridge0 prefixlen 64" > > > > Once you're doing that, rtadvd will start doing the right thing. > > I've just stumbled over this the first time. > > I thought that best practice nowadays was to use the bridge interface for host communications, and leaving the physical interfaces unconfigured, so I'm a bit confused why if_bridge would not allow the auto-assignment of a link-local address. > > If you have two or more bridged interfaces now, and you enable automatic assignment of link-local addresses, you already have multiple link-locals this way; having the bridge have one as well wouldn't make things worse (I think). > http://svn.freebsd.org/viewvc/base?view=revision&revision=149829 "IPv6 auto-configuration is disabled. An IPv6 link-local address has a link-local scope within one link, the spec is unclear for the bridge case and it may cause scope violation." That is the reason. I dont know if its still true but you would need to find someone more familair with IPv6 to comment on it. cheers, Andrewhome | help
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