This Best Practices document aims to provide IPv6 Address allocation guidelines that a network operator can follow while planning the IPv6 subnetting for its network (based on the issues faced and learning’s from IPv6 implementation in NKN and NIC network).
Best Current Practice:
IPv6 addresses generally written in Hex format. Each Hex number represents 4 bit, commonly known as nibble. A nibble boundary is a network mask that aligns on a 4-bit boundary. Subnetting the v6 address at nibble boundary improves efficiency and make it easier to understand for humans* (Machine will anyway read it binary format).