IPv6 subnetting

[Abdul salaam]

Hello IT Guys!

imagine this is the Global unicast ipv6 address taken from ISP1 (2a00:1:a:b:0000:0000:0000:0001:/64) I know the subnetting can be done after 48 bit in subnet id 16 bit.

When i borrow one bit from interface id as follow (2a00:1:a:b:7000:0000:0000:0000:/65) now i confused the fourth field starts from 7 upward or starts from 0 comes to 7 and stops here.

Note : from the right to left first bit value is (8) and three other values total (7).

Thank you

[Harold Ritter · Accepted solution]

Hi @Abdul salaam ,

2a00:1:a:b:7000:0000:0000:0000/65 is not a valid subnet.

Hexadecimal 7000 = Binary 0111 0000 0000 0000

The two valid /65 subnets out of 2a00:1:a:b::/64 are

2a00:1:a:b::/65 and 2a00:1:a:b:8000::/65, as only the first bit after the /64 would differ from the first and second subnets.

N.B.: It is not recommended to subnet beyond the /64 limit for a user subnet.

Regards,

[Abdul salaam]

Thank you sir, how to distribute ipv6 unique local ? it starts with fc00::/64 and goes through fdff::/64...

is this way correct to distribute ipv6 unique local ip address example : 

fc00:1:a:f:b::1/64 next interface id fc00:1:a:f:b:0000:0000:0000:0002/64 goes to fc00:1:a:f:b:ffff:ffff:ffff:ffff/64 ?

[Abdul salaam]

fc00:1:a:f:b::1/64 next interface id fc00:1:a:f:b:0000:0000:0000:0002/64 goes to fc00:1:a:f:b:ffff:ffff:ffff:ffff/64 ?

can we move to left side and turn hexdigits from 0 to f until we reach to fc00::/64 ? like : fc00:fff:ffff:ffff:ffff:ffff:ffff:ffff/64 ?

[Harold Ritter]

Hi @Abdul salaam ,

The proper range for fc00::/64 (fc00:0000:0000:0000::/64) is

fc00:0000:0000:0000:0000:0000:0000:0000 to fc00:0000:0000:0000:ffff:ffff:ffff:ffff

Regards,

[Harold Ritter]

Hi @Abdul salaam ,

fc00:1:a:f:b::1/64 is not a valid /64. Each group you specify at the beginning is 16 bits. So a /64 would be 4 groups of 16 bits and the interface identifier would be all 0 as follow:

fc00:1:a:f::/64

And the valid range would be:

fc00:1:a:f:0:0:0:0 to fc00:1:a:f::ffff:fffff:ffff:ffff

Regards,

[marce1000 · Accepted solution]

 - You may find this app useful : http://www.gestioip.net/cgi-bin/subnet_calculator.cgi

 M.