All IPv6 address assignments are leases. Whether you get the address from a RIR, LIR or ISP. The lease may not be renewed when it next falls due. You may get assigned a different set of addresses at that point. You should plan accordingly.
Exactly the problem, and the reason A) IPv6 is not and will not be a viable option any time soon (soon being before the publication of an IPv6 NAT RFC), and B) why network providers (and other parties who stand to gain financially) are firmly against IPv6 NAT.
A) I think you have a different definition of viable than I do. I have v6 today, running just fine. Not as a home user, yet - but that is coming in the foreseeable future and has nothing to do with the presence of NAT66, or lack thereof. B) I am not a service provider, and I still tend to dis-favor NAT. Not as vehemently as some, but I for the most part, fail to see the need.
If we could get a true accounting of the extra cost imposed by NAT's I would say it would be in the trillions of dollars.
This is exactly the sort of hyperbole, like RFC4864's proposing that application-layer proxies are a viable substitute for NAT, that discredits IPv6 proponents. Those who remember the financial industry's push for SET, a failed encryption technology, will be struck by the similarities in technical vs rhetorical arguments.
While I generally try to avoid the NAT vs NONAT religious debate ... I'll throw in a few comments.
Perhaps what we need is an IPv6 NAT FAQ? I'm suspect many junior network engineers will be interested in the rational behind statements like:
And I suspect lots of new-to-IPv6 network engineers could benefit from more IPv6 exposure :).
* NAT disadvantage #1: it costs a lot of money to do NAT (compared to
what
it saves consumers, ILECs, or ISPs?)
Developed a peer-to-peer application lately? I haven't, but I know some of the issues others have had to go through to work in spite of NAT.
* NAT disadvantage #2 (re: your IPv6 address space) Owned by an ISP? It isn't much different than it is now. (say again?)
Sorry, your befuddlement has passed on to me - I am not sure what you are saying here. The best I can pull from that would be something about PI vs PA space, and I'd comment that both are now available.
* NAT disadvantage #3: RFC1918 was created because people were afraid of running out of addresses. (in 1992?)
Is that a question?
* NAT disadvantage #4: It requires more renumbering to join conflicting RFC1918 subnets than would IPv6 to change ISPs. (got stats?)
* NAT disadvantage #5: it provides no real security. (even if it were
Actually, I think those are different points. NAT-space collisions are a REAL problem, and renumbering due to changing ISPs is also a REAL problem. true
this could not, logically, be a disadvantage)
It is a disadvantage if people believe it is a security thing when it isn't.
OTOH, the claimed advantages of NAT do seem to hold water somewhat better:
* NAT advantage #1: it protects consumers from vendor (network provider) lock-in.
OK, use PI space.
* NAT advantage #2: it protects consumers from add-on fees for addresses space. (ISPs and ARIN, APNIC, ...)
IPv6 addresses (network allocations, actually) are pretty inexpensive ...
* NAT advantage #3: it prevents upstreams from limiting consumers' internal address space. (will anyone need more than a /48, to be asked in 2018)
Yes, /48s have already been outgrown ... so you call up your ISP and justify more, they give it to you. No fuss, no muss.
* NAT advantage #4: it requires new (and old) protocols to adhere to the ISO seven layer model.
Actually, it does more than that. You are thinking of "traditional" network apps, client-server stuff. Think end to end / peer to peer (and I don't mean illegal file sharing) ...
* NAT advantage #5: it does not require replacement security measures to protect against netscans, portscans, broadcasts (particularly microsoft netbios), and other malicious inbound traffic.
Depends on the NAT mode (1:1 or PAT; cone or restricted), and a stateful firewall provides more/real protection ... again, I am not a radical anti-NAT person, I just don't like the pro-NAT hyperbole any more than you favor the opposite :). IMHO /TJ