The simplest way to allocate addresses on a LAN is something called SLAAC. To use SLAAC, an IPv6 router advertises a /64 on a LAN and connected machines automatically select addresses from that /64. So, -by design- the smallest general-purpose network will always be a /64.
The IETF recommends that ISPs hand out /52's to their customers. Why? IIRC, there are no specific examples in the RFC, but I've cooked up a likely scenario:
First, remember that traffic amongst machines in the same subnet never [0] touches a router. This means that traffic within a subnet can only be filtered by endpoints.
Now, imagine that -say- the Open Wireless Router Project [1] gets clever, recognizes that our ISP is allocating a /60 or a /52, automatically splits that into one /64 for each advertised SSID, then sets up firewall rules that create real "guest network" isolation (both from other SSIDs and from machines on the LAN), while still giving every connected machine a globally routeable address.
That would be nice, no? The beauty of it is that an end-user doesn't have to even be aware of IP networking for this to work!
The practice of automatically giving end-user sites the ability to create rather large numbers of subnets will inevitably give rise to consumer networking gear that allows for interesting, secure configurations while still ensuring that all machines on the Internet have a globally-routable IP address.
[0] Let's ignore encapsulation and tunnelling for a moment.
The IETF recommends that ISPs hand out /52's to their customers. Why? IIRC, there are no specific examples in the RFC, but I've cooked up a likely scenario:
First, remember that traffic amongst machines in the same subnet never [0] touches a router. This means that traffic within a subnet can only be filtered by endpoints.
Now, imagine that -say- the Open Wireless Router Project [1] gets clever, recognizes that our ISP is allocating a /60 or a /52, automatically splits that into one /64 for each advertised SSID, then sets up firewall rules that create real "guest network" isolation (both from other SSIDs and from machines on the LAN), while still giving every connected machine a globally routeable address.
That would be nice, no? The beauty of it is that an end-user doesn't have to even be aware of IP networking for this to work!
The practice of automatically giving end-user sites the ability to create rather large numbers of subnets will inevitably give rise to consumer networking gear that allows for interesting, secure configurations while still ensuring that all machines on the Internet have a globally-routable IP address.
[0] Let's ignore encapsulation and tunnelling for a moment.
[1] https://openwireless.org/router/download