Re: NAT-PT Applicability

["Christian Strauf (JOIN)" <ipng@uni-muenster.de>]

> Comments are welcome !!!
Here are my comments.

Para 3.2:
        If more than one box implementing NAT-PT is present, then the
        scalability problem may be circumvented by using e.g. DNS-ALGs
        that can do round-robin or some other form of load-balancing.
        
        Load-balancing also has its drawbacks as the majority of hosts
        cache answers to DNS queries. And additionally, if the NAT-PT
        box and the DNS-ALG are not one unit, failures of one or the
        other are diffcult to handle (due to the current lack of some
        form of communication/surveillance between the two).

It is probably worth to mention that it is to some extent possible to do
load-balancing. Apart from that, I think that the draft is very nice and
surely a good help to get an overview of what problems one can expect
when deploying NAT-PT.

Load balancing NAT-PT is quite a challenge. When using NAT-PT+DNS-ALG to
help IPv6 hosts to connect to the IPv4 world it is more complicated than
simply using a balancing DNS-ALG. It will work nicely until a NAT-PT box
dies or can't handle the amount of traffic anymore. When this is the
case, there have to be some means of notifying the DNS-ALG that this
NAT-PT box is unavailable and has to be left out when assigning IPv6
prefixes to converted IPv4 addresses (assuming that each NAT-PT box
handles the translation for one of those assigned IPv6 prefixes for
converted IPv4 addresses). The question is how this can be done
efficiently. Does the DNS-ALG have to check the NAT-PT boxes somehow? Do
the NAT-PT boxes have to send out notifications that they can't
translate traffic anymore (if there is only a partial failure like too
much traffic/too much CPU usage/...)? Just a thought.

Christian
-- 
JOIN - IP Version 6 in the WiN  Christian Strauf
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