What Is An IPv6 Address? Basics, Benefits & Limitations of IPv6 Addresses

Posted on February 13, 2025

With the rapid growth of devices and the need to stay connected for effective communication and networking, IP Addresses have become an integral part of the internet.

IP (Internet Protocol) addresses are unique numbers or labels assigned to devices to make connectivity easy.

The popular versions of IP addresses in use today are IPv4 and IPv6 addresses.

The IPv4 (Internet Protocol version 4) address is the earlier version of IP addresses. It is 32-bit long and its allocation has long been exhausted. The newer version IPv6 - Internet Protocol version 6, has longer and more secure IP Addresses.

What Is An IPv6 Address?

An IPv6 address is a 128-bit long number assigned to devices for easier identification and networking.

They are usually presented in a hexadecimal format. In this format, there are eight groups of 4 hexadecimal digits which are simply separated by colons (:).

IPv6 Address Structure

Here is an example of an IPv6 address -

2001:0db8:85a3:0000:0000:8a2e:0370:7334

To understand the structure, you need to see the IP address as actually divided into 2 parts – Prefix & Interface ID.

The Prefix is the first part of the IPv6 address. This identifies the network.

The Interface ID is the second part of the IP address, and it identifies the device on the network.

For the example above …

This is the Prefix - 2001:0db8:85a3:0000

This is the Interface ID - 0000:8a2e:0370:7334

They are divided into 64 bits each.

How Does An IPv6 Address Work?

An IP Address Is Requested: A device on a network simply requests an IPv6 address from a server (DHCPv6) or router.
An IP Address Is Assigned: The DHCPv6 server or router assigns an IPv6 address to the device. This is done based on the network prefix and the MAC address of the device.
The IP Address Is Configured: The device configures its IP address, which it uses to communicate with other devices on the network.
Routing: For communication with another device on another network, the IPv6 address is used to route data packets between networks.

Types Of IPv6 Addresses

There are many types of IPv6 addresses.

Common types include:

GUA (Global Unicast Addresses) – Like public IPv4 addresses, they are used to identify devices on the public internet.
ULA (Unique Local Addresses) – Like private IPv4 addresses, they are used to identify devices on a local network.
LLA (Link-Local Addresses) - used on a single link like a local network.
Multicast IP Addresses - used to send data to multiple devices on a network.
Anycast IP Addresses - Though these are used to send data to a group of devices on a network, the data is delivered to only a single device.

Benefits Of IPv6 Addresses Over IPv4 Addresses

Here are some benefits:

Increased Address Space – Being 128-bit long, IPv6 addresses provide a much larger address space than IPv4 addresses (32 bit). This actually makes it possible to connect an almost infinite number of devices to the internet.
No Risk Of Exhaustion – IPv4 addresses have already been exhausted but IPv6 addresses cannot be exhausted because of their 128-bit long address space.
Better Security – With built-in security features like Internet Protocol Security (IPsec) encryption and authentication for IP packets are provided, making IPv6 addresses better secure.
Simplified Network Configuration - IPv6 addresses have a simple network configuration which reduces the need for manual configuration.
Better Mobile Device Support - IPv6 addresses provide much better support for mobile devices.

Some Challenges & Limitations

There is no denying the fact that IPv6 addresses offer several benefits but there are some challenges and limitations also worth mentioning.

Compatibility & Connectivity Issues - IPv6 addresses are not backward compatible with IPv4 addresses without transition mechanisms like dual stack, tunneling etc. The lack of compatibility can cause connectivity issues between devices.
Network Infrastructure Upgrades – Upgrading to IPv6 will usually require upgrades to network infrastructure like servers, routers, switches, and firewalls.
Security Concerns – New security concerns may arise like potential for increased vulnerability to tunneling attacks DoS attacks (Denial-of-service attacks) etc.

Despite its challenges, IPv6 addresses offer far more benefits compared to IPv4 addresses. The limitations and challenges are surmountable and can be addressed with the right knowledge and security measures deployed.

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