Question about 6to4

Martin List-Petersen martin at
Fri May 15 17:04:08 CEST 2009

Kevin Loch wrote:
> Erik Kline wrote:
>> 2009/5/14 Kevin Loch <kloch at <mailto:kloch at>>
>>     I can't recommend the proliferation of public relays as they
>>     cause more problems than they solve.  Private relays are another
>>     story as they help mitigate the problems of the anycast relays.  If
>>     every service provider ran private 6to4 relays for their customers
>>     it would be a Good Thing.
>>     - Kevin
>> The problem is that only addresses half the flow.  You've succeeded in
>> helping your customers get their packets onto the IPv6 Internet
>> efficiently (yay!).  But to get them back 1 of 2 things needs to happen:
>>     (1) Every content provider/destination needs to have good, and
>> preferably local, access to a 2002::/16 return device so it can
>> re-encap the packets and send them to their IPv4 origin.  Otherwise
>> they go off into wherever 2002:/16 happens to point at that time.
>> Obviously, this doesn't scale so well.
> Actually, that is exactly what I meant.  ISP's and hosting/content
> providers should have local and 2002::/16 relays
> whenever possible.  Every relay closer to the endpoints helps.
> The more IPv6 is deployed and used the larger the
> 6to4 problems will become.  Eventually running local 6to4
> relays will need to be as common as local DNS resolvers.

Please combine that with a teredo/miredo relay. Most of the 6to4 traffic
to date comes from teredo and back.

But as such, yes, at an optimum and until we get rid of 6to4, that would
be the scenario.

Kind regards,
Martin List-Petersen
Airwire - Ag Nascadh Pobail an Iarthair
Phone: 091-865 968

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