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Comment by ghshephard | Hacker News Reader

The original belief with IPv6 is that End Users would route through their ISPs address space, and the IPv6 made renumbering so easy, that it would be simple for end-users to change providers and renumber.

This turns out not to be the case.

IPv6 will not reduce the size of the routing tables. Anybody with prefixes, and PIAS right now, will likewise get a /48 of IPv6 space and start advertising it into BGP.

If anything the more easily available space may result in bigger routing tables as a result. (Not everyone was able to get a /20 - particularly outside of ARIN space. For example - IPv4 addresses come very dear in places like Dubai.)

And NAT doesn't go away with IPv6. That was another belief that did not survive its first encounter with reality. It's simply called "Network Prefix Translation" now (NAT by another name)

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> And NAT doesn't go away with IPv6. That was another belief that did not survive its first encounter with reality.

If it doesn't go away, it will be only because of ISP greed (i.e., charging customers for a larger number of publicly routable addresses). Otherwise, there simply is no reason not to give every customer a /56 or even a /48, given that routers won't be able to route prefixes longer than that anyway.

Fortunately, most ISPs offering native IPv6 so far have turned out not to be that greedy.

It has nothing to do with ISP greed. There is no shortage of IPv6 addresses, and, ISPs have every motivation to encourage their customers to use their IPv6 space.

The reason NAT doesn't go away is that customers don't want to use their ISPs IPv6 space, they want their own provider independent space.

The easiest way to do that, is to address all your devices from RFC 4193 ULA space, and then, on your perimeter, do RFC 6296 Network Prefix Translation to the ISPs IPv6 space.

Then, when you change ISPs, you simply make a single change on your perimeter rather than having to renumber hundreds of internal devices, DNS, configurations, etc...

I understand the argument for enterprise networks. Residential customers have everything to gain from using their IPv6 space, and provider-independence isn't an issue for them.

It's worth noting that NPTv6 is a lot better than NAT, though. For one thing, it operates strictly at the IP level and doesn't muck about with the transport layer. So, for instance, if you want to use a transport other than TCP or UDP, it should be possible - at least in principle - even if you are NPTing to and from ULA space. That's something you haven't been effectively able to do on the Internet for the past 20 years.

Totally agree with you across the board.

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