Simple example with a unique-local IPv6 Subnet
Example subnetting for a class B private network
Subnetting a smaller /69 IPv6 Network
Subnets showing all values for 8 bits - 256 rows
Illustrative distribution to RIRs from global unicast 2000::/3 pool
Fringe case showcasing IPv4 mapped IPv6 (::ffff:a.b.c.d/96)