IPV6 at home: my ISP delegates me a static IPV6 /56 subnet, how can I set up an IP scheme & DHCP6 for my network?

Question

My network looks like this:

(Cable Modem/Router) <-> (PfSense Router) <-> (Internal Hosts)

The IP (changed for security) of my cable modem is:

IPv6 Address    2001:1:a481:300:6eb0:ceff:fe8d:f25b/64
IPv6 Prefix     2001:1:a481:300::/56

What should I set as the LAN and WAN IPs of my PfSense Router?

Also in the DHCP6 server, I'm asked to complete:

DHCP6 Range
DHCP6 Delegated Prefix Range and Subnet  

What should my router (pfSense) IP be in the DHCP6 settings for the clients?

In general I'm confused how to subnet this properly. This is for a very simple home network, but I'd like to learn how this stuff works. Any help would be greatly appreciated!

Solution

IPv6 Prefix     2001:1:a481:300::/56

if you have 56 prefix it would be nicer to include zeroes

completed prefix looks like this:

2001:0001:a481:0300:0000:0000:0000:0000/56

now we can see the prefix

2001:0001:a481:0300:0000:0000:0000:0000/56

In IPv6 the smallest subnet size (prefix) is 64; so you have 8 more bits to create subnets (2 zeros after 3)

if you want only one simple subnet for your homenetwork, the easiest way is to choose some address from your subnet - prefix, for example:

2001:1:a481:301::/64

this will be your home subnet now you have to choose the addresses for wan/lan for ex.:

2001:1:a481:301::1 -wan

2001:1:a481:302::2 -lan

DHCPv6 personally I don't prefer this. IPv6 have included autoconfiguration using NeighborDiscovery protocol. But If you want It the prefix would be

2001:1:a481:302::/64

and DHCPv6 range for example

2001:1:a481:302::100-200

and at last:

You also have to ensure that correct routes are on your devices and the traffic will be routed

Comments

[Ricardo]

Are you trying to setup your own DHCPv6 server or is this a service that you can enable on the ISPs cable modem/router? If this is on the cable modem/router then you need to somehow enable it to delegate an entire subnet to your pfSense router. Getting a /64 address is not enough if you want a simple configuration. Subnetting a /64 address will break autoconfiguration.

[kasperd]

It is unclear from your question which of the two routers the /56 has been routed to. If the /56 has only been routed to the outermost router, you might not yet have a prefix routed to the innermost router. If no prefix is routed to the innermost router, then the first thing you need to do is to get the outermost router to route a prefix to the innermost router (a /57 or a /60 would work for that).

[pershing]

correct, it was a mistake

[kasperd]

When you say NetworkDiscovery, do you mean router advertisements or neighbor discovery?

[pershing]

neighbor, of course, router advertisments are based on ND