Re: Public IPv6 anycast service?
Hello,
Am 04/07/2014 10:33 AM, schrieb Bastien Durel:
> Le dimanche 06 avril 2014 à 18:00 +0200, Jan Lühr a écrit :
>> Hello folks,
>>
>> I'm trying to setup an anycast DNS-Service using Debian 7.4 and global
>> unicast addresses.
>>
>> At the moment I'm adding the anycast-IP to the second server
>> "ip -6 addr del 2001:67c:20a0:b103::2/64 dev br-ff"
>> the kernel runs into a duplicate address detection issue
>>
>> [81066.037496] br-ff: IPv6 duplicate address 2001:67c:20a0:b103::2 detected!
>>
>> and the address is not reachable on that server.
>>
>> What's wrong here? How can I build an anycast DNS service?
> Hello,
>
> AFAIK, anycast is implemented using routing. (I never ran IPv6 anycast
> services, but I run IPv4 ones). So you have to add you anycast-ip to
> some dummy interface (for example ip a a 2001:67c:20a0:b103::2/128 dev
> dummy0) and redistribute the prefix via IGP (ospf, ibgp ...)
> You cannot have an address twice on the same link.
Thx for your comment. What I figured out so far:
-> In principle you can:
http://tools.ietf.org/html/rfc4861#section-7.2.7
-> This is not (yet?) implemented by IP
Setting anycast-addresses using "anycast" has no effect.
http://man7.org/linux/man-pages/man7/ipv6.7.html
I wonder, whether it will be implemented some day, soon.
But I'm not sure, if this information is still accurate.
-> Routing - yes it is an option. Some (all?) Linux distributions by
default do not accept small routes using radvd, Link-Layer multicast is
not really possible. Thus, it requires to routers to cooperate.
Greetz, Jan
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