Good ${greeting_time}, Michiel!

12 Jan 2022 15:21:30, you wrote to me:

 MvdV>>> It is not that 2^64 addresses are not enough for all my
 MvdV>>> devices, it is that a /64 can not be divided into subnets.
 AV>> And on my early experiments, when the /64 was the only block
 AV>> I had, that was really great.
 MvdV> Yes, now that you mention it, I remember yuo experimenting
 MvdV> with dividing a /64 into 32 bit subnets.

Yes, of size /96

 MvdV>>> That is the way it is designed. A /64 is the smallest subnet.
 AV>> No. The /64 is the default subnet size, and people normally
 AV>> SHOULD NOT (as in FTA-1006) split these blocks further, but
 AV>> that IS possible and NOT prohibited.
 MvdV> OK, so I stand corrected, it is possible.
 MvdV> But many things won't work any more. SLAAC comes to mind.
 MvdV> So one /should/ avoid it.

Exactly.

 MvdV> At first glance one would say: a /64? what a waste! But keep in
 MvdV> mind that "waste" is only a problem when there is a shortage.
 MvdV> "Waste and shortage" is IPv4 think.

IPX had 32 bits for network number and 48 bits for node number (actually 47, because it used MACs for the node numbers by default).

And many good features of IPv6 were inspired by this protocol.

 MvdV>>> So... if one wants/needs more than one subnet, one needs more
 MvdV>>> than one /64. That is the way it is. It should be no problem,
 MvdV>>> there is enough for everyone.
 AV>> Here in Russia the de-facto standard is one MAC-based IPv6 address
 AV>> for the outer-side link and /64 subnet routed via that address to
 AV>> the customer's LAN. Additional subnets may be requested as well,
 AV>> but ISP admins say most people don't request them.
 MvdV> So most people in Russia do not need more than one subnet....

This may be safely extrapolated to the whole globe: most people just don't bother of separate subnets in their LANs - they simply use plastic routers putting all internal devices in one big "LAN" segment (computers, phones, fridges, phones... everything) and allow one-way connections to "external" networks, regargless of whether they use IPv4 or IPv6.


--
Alexey V. Vissarionov aka Gremlin from Kremlin
gremlin.ru!gremlin; +vii-cmiii-ccxxix-lxxix-xlii

... god@universe:~ # cvs up && make world
--- /bin/vi