I find myself wondering, don't they get support calls from
customers having to deal with the problems caused by the NATs?
Because they don't answer them. In the process of doing the
work that led to RFC 4084, I reviewed the terms and conditions
of service of a large number of ISPs in the US (and a few
others) who provide low-cost Internet connectivity. Some
prohibit connection of more than one machine to the incoming
line/router/modem. Others provide a NAT-capable router but
prohibit the customer from making any changes to its
configuration and from running any applications that don't work
in that environment. And still others indicate that customers
can supply their own NATs, but must obtain any support
elsewhere. All of these prohibitions are "enforced" the same
way -- if the user calls with a problem, he or she either
(i) is told that there is no support for violations of the rules
and offered the opportunity to be disconnected (often with a
large "early termination fee") or
(ii) is instructed to disconnect all equipment between the
machine in question and the router, and see if the problem still
occurs. If it doesn't, then the ISP has no problem and the
customer's problem is of no interest.
Well, the reason I asked is that when I got my DSL line, my ISP
supplied me with a modem that does NAT - but only for a single host.
As best as I can tell this is because the box needs to run PPPoE
on the carrier side and DHCP on the host side, and the only way that
the DHCP server can give the host an address under those conditions is
to do NAT. So in this case (which I have no reason to believe is
atypical) the ISP is supplying the NAT - and they do so even for
customers who pay them extra to get a static IP address!
And yes it does break things even when there are no other local hosts
involved and no additional boxes between the modem and the customer's
host. So I have a hard time believing that ISPs don't get support
calls about failures due to NATs, at least when they install the NATs.
Now of course this ISP does have a T&C that prohibits running a server,
but "server" is a pretty vague term, and you don't have to be running
any kind of server to suffer from NAT brain-damage.
Keith
p.s. fwiw the workaround in my case was to tell the modem to work in
"passthrough" mode and configure my local router to run PPPoE.
Under those conditions, I'm happy to report, 6to4 works just fine.
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/ietf