So, the point is that given a
/31 prefix, how to get subnets from that, and his example is for
/36 subnets. It works the same way for IPv6 as for IPv4, except that the IPv6 address is 128 bits, and the IPv4 address is 32 bits.
Think about this; the current Global IPv6 address range is
2000::/3 (a non-nibble boundary), and every Global prefix is a subnet of that, generally allocated as a
/48 prefix for each site, giving you
/64 networks per site. That means there are
48 bits per prefix, minus the
3 bit prefix equals
45 bits), or
35,184,372,088,832 prefixes for standard
You can break prefixes on any bit boundary, but it is simpler to use nibble boundaries, and IPv6 has plenty of addressing to do that. The currently allocated global address space comprises only one eighth of the entire IPv6 address space.
In most cases, your IPv6 subnet to which hosts connect will be
/64 networks because networks of other sizes break some IPv6 features. What you are really concerned about are the prefixes smaller than
/64 that are subnetted out to