Subject: (ngtrans) RE: the ban on anycast sourcing (was: shipworm discussion and last call)

From: "Christian Huitema" <[email-masked]>
Date: Thu, 27 Sep 2001 08:55:42 -0700

> > > I would personally be perfectly happy if the ban on 
> sourcing packets
> > > from IPv6 anycast addresses was lifted. There are clearly 
> operational
> > > issues each time one use such a facility, but a complete 
> ban is both
> > > counterproductive and unrealistic.
> > 
> > bingo! 
> 
> Anycast source addresses do have serious problems.  I had gotten the
> impression that the IETF was opposed to putting more bullets in the
> gun that's aimed at the unwary foot.  Not so?
> 

Part of the problem is, you cannot distinguish an anycast address from a
unicast address. Take the example of an hypothetical DNS server farm,
that would publish one IPv6 address in the DNS, and use load balancing
technology to direct the incoming requests to one of its servers; the
server would be programmed to send the reply from the published address.
Can I develop such a server farm today? Indeed I can. Am I using
anycast, or unicast? Well, we get the same address used by multiple
interfaces, so it definitely looks like anycast. Can the protocol police
stop me? Don't think so. So, if it cannot be stopped, why do we bother
legislating against it?

-- Christian Huitema