On 2023/4/18 23:10, James Knott wrote:
On 2023-04-18 11:04, Nohk Two wrote:
BTW, I run pfSense for my firewall/router and it supports multiple /64s. If my modem was in gateway mode, I'd only get a single /64.
I have a question regards to the amount of the IPv6 addresses one can get from his ISP.
For my case, my router use PPPoE to get the IPv6 from the ISP. The router got an IPv6 prefix for the router. The router also issued the DHCP-PD to the ISP to get another IPv6 prefix.
The first IPv6 prefix is for the router itself and the second IPv6 prefix is used to configure router's LAN devices either by the SLAAC and/or RDNSS and/or DHCPv6...
My question is that is it correct that, for the first IPv6 prefix, the router could get 2^64 (or 2^72 in your case) IPv6 addresses since the ISP assigned the IPv6 prefix to the router ?
Of course, router has no reason to assign so many addresses on itself. Router usually assign one IPv6 address which the interface id is based on the MAC address.
Actually, it's a bit different. First off, the link local address is used for routing. This address starts with fe80 and every IPv6 capable device has one. Second, while my router has a single IPv6 address, it's prefix is a /128. This means it can't communicate directly with anything. All traffic for that address has to be routed via the link local address. Ok, this is very clear. Thank you very much.
I have to correct my original statement that the first IPv6 prefix should be a complete /128 IPv6 address. And the MAC address derived interface id must be learned by the ISP during the PPPoE handshake process.
In fact, you don't even need a global address on the WAN port. If you had to reach it from elsewhere, you could use any other global address in it, such as the LAN address. It makes no difference, as any address on the router has to be reached over the link local address.
You are right, I also found this global WAN IPv6 address is useless. And the default gateway is the router's link local address in my LAN devices.