That's indeed the original reasoning for building in on-the-fly renumbering to IPv6, but it was supposed to still be a rare event.

But consider: (1) that for ages the route table growth has been slow due to v4 shortage, and router memory has kept getting cheaper on the normal memory cost curve for this plateau phase in history, and (2) Consumer ISPs have been abusing this and making prefixes jump around even on CPE reboots, instead of having them stable for months and years like is the design, and (3) mechanisms to smooth out renumbering haven't been deployed because ISPs have gotten away with doing [2] without any mitigations.

The 'net infra could probably afford to start giving many more people portable blocks, and it would be only fair that ISPs would have to pay a bit for their sins regarding [2], and to this would add incentives to do [3].

regarding (1), the route table growth is actually not slowing. as we run out of IPv4 addresses there is more fragmentation as bigger blocks are split up and sold.

In graphs I saw it slowed somewhat.. but even if you are right, this is still waste of router memory since those same routes could be for much bigger v6 blocks instead of tiny v4 ones.

And also, in absolute terms it's currently tiny, ~ 2 M routes that can be represented in a couple of addrs worth of space each in line card memory when deciding just which interface to forward, and keeping in mind that only core routers that don't outsource transit to other upstream telcos have a need to keep this in memory.

Fair point. Let me request them for free from my ISP then. None of this "pay $20/mo for a static prefix" garbage. IPv6 loses all of its benefits if my entire network is ephemeral and has to rely on prefix delegation propagation.

You agree it's a "fair point" that this would be incredibly expensive, but then you say you want it to be free.

Is it simply that you don't understand why it's incredibly expensive? It means everybody who does network routing has to buy extra hardware to track all this useless noise you've decided ought to be "free", that hardware costs money.

Your ISP choosing to charge you for stuff that doesn't cost them anything is completely separate. I would say "Choose an ISP which isn't shit" but you're probably American and have no such choice. Too bad?

My correction is for static prefixes from an ISPs block, I don't see that as an unreasonable free request. No peering, they just static route that block to the IPv6 address they assign you.

Sure, yes, there's no reason this should be hard for your ISP to arrange. I guess it might be slightly painful for large ISPs say if you're a huge American ISP and customers can just up and move all their gear from San Francisco to New York and expect the IP addresses to stay the same that's kind of annoying to implement and the service for those customers will either suck (a user in New York finds all their data routes via the West Coast) or cost you more.

But in the general case, for a customer who is just using the Internet from the same place as last time, there's no benefit to changing their IP addresses and clearly there's no reason static addressing shouldn't be free, it's just like one database entry for them to do it.

I could imagine them explaining OK, you get static BUT it might change if you move home or something, and that feels pretty acceptable to me.

For what it's worth I get static IPv6 and IPv4 (although of course the IPv4 is a tiny block, only a /27 IIRC whereas I have a /48 of IPv6) but I'm in the UK and with a specialist ISP that cares a lot about this stuff.

> For what it's worth I get static IPv6 and IPv4 (although of course the IPv4 is a tiny block, only a /27 IIRC whereas I have a /48 of IPv6) but I'm in the UK and with a specialist ISP that cares a lot about this stuff.

Even some of the large ISPs can get it right. I used to have fiber optic service from a large telephone company (starts with "C" ends in "EnturyLink") and could use their account management portal to go and get anything up to a /26, complete with setting up reverse DNS, just by clicking a button and agreeing to a relative pittance of money. I think the /26 was $40 per month and the /28 I had was $10 a couple of years ago. They would give me a static IPv6 /48 for nothing, just a click, and delegate the reverse DNS zone to me. A /56 that was supposedly dynamic but never actually changed was given by default.

The problem seems to be which ISPs want to do what. ISPs run by phone companies seem to think of their networks, and the customer networks attached to them, as actual internetworked networks. ISPs run by video companies seem to think of their networks as extensions of distribution systems for linear television channels.

If you move your physical connection, renumbering seems totally reasonable (they need to handle internal routing). Otherwise, I see no reason the assigned address shouldn't be static, other than money extraction and perhaps privacy.

Well, prefix delegation would be fine as long as the ISP guarantees that the delegated prefix will be stable. But they aren't guaranteeing that unless you pay extra for a static v4 (because they're tying v6 assignments to v4 assignments), which is indeed asinine.

@tialaramex is making their point rather poorly, using the term "expensive" without explaining how, and being a bit aggressive about it.

The more ASes that exist, the more routes need to be propagated. If every household were theoretically assigned a network that they could take with them anywhere, and advertise, a well-connected router would have millions and millions of routes to track and forward.

One of the goals of IPv6 was to make the Internet more hierarchical to avoid this.

I agree with your point. I should be able to get a static PD from my ISP (a /56 or /60 easily) and that should stay the same for all time, given a MAC address. In other words, PD should be stateful.

I have thought about setting up my LAN with "Unique Local Addresses" and doing NAT66 if I can ever manage to get a public IPV6 address from my ISP.

You don't need to do NAT66; just enable ULA. Interfaces can have multiple IPv6 addresses, not just one. So you will get your static local addresses and for outbound traffic, a random globally routed address from the currently assigned prefix would be used.

I know routing table bloat is annoying and it's hard to do tons of routes in an ultra-fast way, but I do want to point out that "millions and millions of routes" translates to "tens and tens of megabytes".

But if you're doing fast hardware routing, that's tens and tens of megabytes of TCAM, not DRAM. It's more akin to CPU cache in terms of latency, capacity and cost.

You can get a $600 Epyc with 128MB of cache. That shouldn't be too much compared to the tier of router we're talking about, right?

That's L3 cache though; they only have 0.5 MB of L2 cache per core.

I'm not really sure how much each of these types of memory cost, but I did find [1] which says "The cost of TCAM is also about 30 times more per bit of storage than SRAM". That suggests a CPU with something more like 0.5-1 GB of L3 cache would be a closer comparison.

[1] https://research.ijcaonline.org/volume115/number7/pxc3902299...