Running rtadvd or DHCPv6 server via if_bridge interface

Stefan Bethke stb at
Thu Mar 18 22:45:12 UTC 2010

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).

Slightly confused,

Stefan Bethke <stb at>   Fon +49 151 14070811

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