"Worley, Dale R (Dale)" <dworley@xxxxxxxxx> wrote: > Also, NAT provides the ability to connect a small network to a service > provider that only provides a single DHCP address, or wants to charge > extra for every device you attach to its network. NAT is a > significant technical tool in the business conflict between user and > service provider. Having been the admin of some small offices that set up Internet connections, from my perspective it worked like this: In the mid-90s, we just got enough address space for our hosts. Simplest thing to do. Later on, that got too expensive. Why? IPv4 address exhaustion. Addresses where nowhere near exhausted, but ARIN started putting the brakes on and making ISPs justify their address use more, and it was costing more, so "just get enough address space" started getting significantly more expensive. So we'd get some sort of basic "business class" service with, say, 4 IPs, and NAT the office behind a simple high-end consumer grade NAT router. Did we ever do this because we *wanted* NAT? Far from it. A very small office doesn't care, in my experience, about any of the things NAT provides. Renumbering? Chances are we'd move to a new building across town long before that happened, and get new Internet service. We have too few hosts, and the couple of in-house servers would not be any trouble. Internal network structure? It's just a bunch of hosts on one switch. It's not a conflict with the ISP. If they could, they'd provide us the IP address space we want at an incrementally higher price, and we'd pay it. They'd get more money that way. But they can't afford to, so they charge a price high enough to make us, the small office, deal with the annoyance of setting up and administering NAT. Because it *is* an annoyance we'd rather do without. If we could pay the ISP a bit more for the simplicity of just having a /26 that our network could comfortably fit in, we'd do it. Once an office gets large enough, NAT starts to provide benefits. But in my experience with very small offices (say, under 25 people), NAT is an annoyance we'd rather do without if we could affordably get the IP space we want. In other words, it's just a natural consequence of there not being enough IPv4 address space. ISPs and small offices are reacting in a reasonable way to that fact, and doing so cooperatively. Both of them could be a bit happier if there were enough address space for everyone - ISPs would make a bit more money, small offices would have a simpler Internet connection without NAT - but that's not an option. I haven't admin'ed a small office in enough years, that IPv6 was not an option when I did, and I don't know what the practical state of it is today. If an ISP offered native IPv6 with their regular business class service, and the host OSes on our network just worked with it, that's what I'd have picked, so we could avoid the choice between NAT and address scarcity. All IPv6 would need to offer would be the combination of enough address space to avoid NAT, and a cost not significantly higher than the 4-address IPv4 service. As a small office, we wouldn't worry about multihoming, renumbering, or any of the other things that keep coming up on this thread. We'd just want to be connected as simply as possible. NAT is complexity we never wanted. -- Cos