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## + - How to subnet IPv6 ?->

Submitted by suraj.sun
suraj.sun (1348507) writes "Subnetting IPv6 sounds very complex but all you need to do is how an address is formed and how to efficiently use CIDR notation. An IPv6 address has 8 sections seprated by coloums and each sections has carries 4 hexadecimal digits(http://anuragbhatia.com/networking/how-to-subnet-ipv6/). So an IPv6 address is something like: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx – Each x can have a hexa decimal value i.e from 0 to 9 and a to f. This turns out to be 16 + 16 + 16 + 16 + 16 + 16 + 16 + 16 bits = 128bit, which means total possible addresses in IPv6 space is 2^128.

In most of cases RIRs like ARIN/APNIC allocate a /32 IPv6 block. This means first 2 sections 16+16 bits are reserved and rest 6 sections i.e 128-32 = 96 bits are available for use. Let’s pick example of Google’s block, 2404:6800::/32 from APNIC in Asia. Since only first 32 bits are reserved, block 2404:6800::/32 goes from 2404:6800:0000:0000:0000:0000:0000:0000 to 2404:6800:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF"