Understanding IPv6 Address Structure and Types in Easy way

Dive into the world of IPv6 with the vast address space. Learn about different types of IPv6 addresses, including unicast, multicast, and anycast.

The advent of IPv6 has ushered in a new era of internet protocol addresses, offering a solution to the imminent exhaustion of IPv4 addresses. Unlike its predecessor, IPv6 uses a 128-bit address system, significantly expanding the number of possible addresses and introducing a range of features designed to optimize internet connectivity in the modern digital landscape.

The Structure of IPv6 Addresses

An IPv6 address is a 128-bit alphanumeric string, structured to facilitate easy identification and location of network devices. These addresses are divided into eight groups of four hexadecimal digits, separated by colons for readability. The ability to abbreviate these addresses by removing leading zeros within a block and condensing consecutive zeros using a double colon (::) simplifies their representation without losing uniqueness​​​​.

For example, the address 2001:0DB8:5002:AB41:0000:0000:0000:0801 can be abbreviated to 2001:DB8:5002:AB41::801, adhering to the conventions of omitting leading zeros and using a double colon to represent consecutive zeros​​.

IPv6 Address Basic Details

  • IPv6 Address size is 128 bit
  • Like octet of 8 bit in IPv4, here we have hextet of 16 bit
  • Means 128 bit in Hexa-decimal format consist of 8 hextet
  • Hextet are separated by column (:)
  • IPv6 having 32 Hexa-decimal Character in Address (Note: Single Character of Hexa-Decimal have 4 bit)
  • Means we have 4 Character in 1 Hextet/Blocks and that kind of total 8 hextet
  • There are no Class and no Subnet mask in IPv6
  • All communication is based upon CIDR Notation (Network Bit define with Slash Notation)
  • By Default Prefix Length is 64 bit
  • As we discussed that 32 Character in Single IPv6 Address, By Default 16 Character for Network an 16 Character for Host

Example

ABCD:EF00:1234:5678:1234:5678:90AB:CDEF/64

ABCD:EF00:1234:5678:0000:0000:0000:0000 (Network ID)

Another example from same Network
ABCD:EF00:1234:5678:0000:1234:1234:1234/64

Abbriviating Address (Shorten the Address)

Original Address
2001:0000:0001:1234:0000:0000:0000:0001

Rule 1 => You can ignore all leading zero
    Example: 0005 Rs. and 5 Rs. are same.

    Above original address now shorten as below after applying Rule 1
    2001:0:1:1234:0:0:0:1

Rule 2 => If we have continue multiple Zero in Single or Multiple Block/Hextet Then you can merged with ::

    Above original address now shorten as below after applying Rule 2
    2001:0:1:1234::1

    T-n-C / Condition for Rule 2
    We can use this Rule no 2 only one time in single IPv6 Address
    We can't write above address as more short like (2001::1:1234::1)
    This is actually giving assumption for below possibilities

    2001:0000:1:1234:0000:0000:0000:1
    2001:0000:0000:1:1234:0000:0000:1
    2001:0000:0000:0000:1:1234:0000:1

Types of IPv6 Addresses

IPv6 introduces several types of addresses to accommodate different networking scenarios:

  • Unicast Addresses are used for direct communication between a single sender and a receiver. These include Global Unicast Addresses (GUA), Link-Local Addresses, and Unique Local Addresses (ULA), each serving different scopes and purposes​​​​.
  • Multicast Addresses enable the delivery of packets from a single source to multiple destinations. Characterized by the prefix FF00::/8, these addresses support group communication efficiently without the need for broadcast addresses​​​​.
  • Anycast Addresses are assigned to multiple interfaces, typically across different nodes, with packets delivered to the nearest interface based on routing topology. This is particularly useful for load balancing and redundancy​​.
IPv6 Addresses

IPv6 Addressing Range

Sometime also known as Types of IPv6 Address

Globally Unique (like a Public IP of IPv4)

Any IPv6 address starting with 2 or 3 that is known as Globally Unique Address
2xxx::
3xxx::

Unique Local (like a Private IP of IPv4)

Any IPv6 address starting with FC or FD that is known as Unique Local Address
FCxx::
FDxx::

Link Local (Little bit like APIPA)

Any IPv6 address starting with FE80 that is known as Link Local Address
FE80::

Loopback Address

In IPv6 we have only one address for loopback which is:
::1

Multicast Address

Any IPv6 address starting with FF that is known as Multicast Address
FFxx::

Key Features and Configurations

IPv6 enhances network management and security through features such as Stateless Address Auto Configuration (SLAAC), allowing devices to automatically assign themselves a unique IP address, and the optional use of IPSec for authentication and encryption. Moreover, IPv6 supports a minimum packet size of 1280 bytes, ensuring that packet fragmentation is minimized and handled more efficiently by the source device rather than intermediate routers​

Miss the Introduction of IPv6? Click here to read