Understanding IPv6

IPv6 addresses are cryptic to look at, explains semantics of IPv6 address.

No Broadcast, only multicast i.e a special multicast address. All host interested in multicast packet join multicast group first. IPv6 supports ANY-CAST i.e multiple host having same address. Router forwards the packet to nearest any cast server.
No NAT, multiple IP addresses per interface. Every inf. has link-local and a global scope address for internet/external net. Global unicast address is generated using Interface Identifier ( i.e. using physical MAC address ).
Equivalent of loop back address (127.0.0.1) is ::1/128
An IPv6 address is made of 128 bits divided into eight 16-bits blocks. Each block is then converted into 4-digit Hexadecimal numbers separated by colon symbols.

IPv6 provides some RULES to shorten the address.

2001:0000:3238:DFE1:0063:0000:0000:FEFB

Rule.1: Discard leading Zero(es): In Block 5, 0063, the leading two 0s can be omitted.

2001:0000:3238:DFE1:63:0000:0000:FEFB

Rule.2: If two of more blocks contain consecutive zeroes like block 6 & 7, omit them all and replace with double colon sign ::

2001:0000:3238:DFE1:63::FEFB

If there are still blocks of zeroes in the address like block 2, they can be shrunk down to a single zero.

2001:0:3238:DFE1:63::FEFB

Bonus points if they can show you they've been through the Hurricane Electric schpiel.

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