IPv6 Notes

Layout

         ---- Network        ---- Host
         |                   |
         |                   |
/-----------------\ /-----------------\
2001:0DB8:0000:0000:0000:0000:0000:0000
\-------/ \--/ \--/
    |      |    |
    |      |    --------------- Site Subnetting /64 (16 bits)
    |      |
    |      -------------------- ISP -> Site /48 (16 bits)
    |
    --------------------------- RIR -> ISP /32 (32 bits)

Short Hand

So an IPv6 address is 8 “hextets/quartets/quibbles” In a hextet leading 0s can be dropped but must leave one for a place holder so:
2001:0db8:e01b:fe00:0000:0000:0000:0001

Can be shortened to:
2001:db8:e01b:fe00:0:0:0:1

If you have a “zero” hextet (ie: :0000:) OR multiple adjacent zero hextets together (ie::0000:0000:) they can be additionally shortened to :: BUT only ONCE per address (since it would be impossible to extract how many were in each)

So from above we have 3 hextets together:
2001:db8:e01b:fe00:0:0:0:1

Can be Shortened to:
2001:db8:e01b:fe00::1

Three Examples:
2001:0db8:e01b:fe00:0000:0000:0000:0001 -> 2001:db8:e01b:fe00::1
2001:0db8:e01b:fe00:0000:0000:0001:0001 -> 2001:db8:e01b:fe00::1:1
2001:0db8:e01b:0000:0000:0001:0000:0001 -> 2001:db8:e01b::1:0:1