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Comment by mastax | Hacker News Reader

Related question: I asked my ISP for IPv6 and they gave me a static assignment like this:

    WAN: A:B:C:D::1/126
    LAN: A:B:110::/48

I tried to read up on this but am still confused. Why are they giving me WAN and LAN addresses? I thought the whole point of IPv6 is that you give your devices publicly routable IP addresses. If an address is publicly routable, what's "LAN" about it? I haven't been able to find a working configuration for Unifi, though their IPv6 support is like 20% implemented at best.

And no, the LAN subnet isn't in the ULA or link-local space.

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Traffic for that /48 will be routed to your router. You're free to divvy up that /48 into /64 subnets on your LAN. Eg you can make one subnet A:B:110::/64, another A:B:110:1::/64, and so on all the way to A:B:110:ffff::/64. ("Making a subnet" == setting up at least RA to advertise that prefix, along with DHCPv6 / SLAAC options as you want.) Then LAN devices on those subnets can use any IP in the /64 for themselves.

In your case it's a static assignment, but otherwise it can be assigned via DHCPv6-PD (when your router asks for a WAN IP using DHCPv6, it also gets told that some prefix like your /48 has been "delegated" to it). The result is the same.

> Traffic for that /48 will be routed to your router.

Okay, now it makes sense. I'm not sure how else I expected it to work.

A router (discounting unnumbered and ARP/NDP proxying) will have at least 2 IP addresses, otherwise how can it route packets between two different networks? It needs one IP for itself on each network.

For IPv4, you will be given <some random IP> on the WAN side and typically you assign 192.168.x.x (or other RFC1918 addresses) to your devices on the LAN side.

For IPv6, you will be given two random IP blocks with similar usage as the IPv4 ones, except that the LAN side is now publicly routable.

If you want your devices on your LAN to have publicly routable IP addresses, by definition they need to be GUA. I think you just mis-understand what end-to-end connectivity means.

Your "WAN" is a small transit subnet between your router and your ISPs, while the "LAN" is the actual public ip space you will be assigning to your end devices.

>If an address is publicly routable, what's "LAN" about it?

Routable or not, it's LAN because it's in your network behind your router. It's just an identifier.

Nah the point was that the public IPv4 space has run out. Anything like removing NAT or making everything routable is just more icing on the cake.

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