Question about 6to4

Ted Mittelstaedt tedm at
Fri May 15 19:21:08 CEST 2009


> -----Original Message-----
> From: at 
> [ at] On 
> Behalf Of Martin List-Petersen
> Sent: Friday, May 15, 2009 8:04 AM
> To: Kevin Loch
> Cc: ipv6-ops at
> Subject: Re: Question about 6to4
> 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.

The ONLY reason I was even looking at 6to4 was because Linksys
supported it in their corporate firmware load on the RVS 4000 which
is one of the few really cheap routers on the market that has
full stateful inspection, can block p2p protocols by looking at
the data payload, and does a lot of way-cool stuff that is really
essential for a small business.  Stuff that you CANNOT do on a
dd-wrt load on a sub-$40 low-flash router. I had thought
that such support might indicate they would migrate 6to4 downward
to their cheap products.

But, after understanding how it works, it is just not worth pursuing.

I see this as a chicken-and-egg issue.  Linksys won't migrate 6to4
down to their cheap product unless a lot of ISP's start fielding
6to4 gateways.

However, the 6to4 system design takes so much control of where the
traffic routes away from ISP's that nobody looking at this from
a business perspective could possibly support the scheme.  The
largest amount of ISP network support for end users deals with the "last
mile" the traffic path from your peers to their desktop.  With 6to4 you
now have user's return traffic streams passing through gateways you have
no control over, from hosts you have very little control over, and by
the time it's passed from a peer to you, there's been far more
chances to screw it up than a usual IPv4 packet.

I could just see me calling Paypal for example and telling them that
they have to contact Hurricaine Electric and tell HE to fix a routing
problem because one of my customers is having trouble logging onto
Paypal's IPv6 server.  That conversation would be a true exercise in
futility because anybody at Paypal who really understood the problem
would just laugh and tell me that my network shortcomings that are
making me push my customer to use 6to4 to begin with, are not their
problem, and if I ran native IPv6 to my customer they would help me,
otherwise, kiss off.

6to4 isn't a transition mechanism, it's a laboratory experiment that
escaped from the lab and is being supported by a few die-hard techs who
have no understanding of business.  Seriously!!!

I'd much rather see ISP's deploying IPv6, such as the ISP I work for,
strongly discourage 6to4 so that vendors like Linksys don't take
development time away from incorporating native IPv6.


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