Difference Between IPv4 and IPv6

Last Updated : 30 Sep, 2025

The Internet Protocol (IP) gives every device a unique address so it can send and receive data online.

IPv4: The older version, uses a 32-bit address (about 4 billion addresses). With the rise of the internet and IoT devices, these addresses are nearly used up.
IPv6: The newer version, uses a 128-bit address (virtually unlimited addresses). It was created to overcome the shortage and support the future growth of the internet.

Limited Addresses: IPv4’s 32-bit space cannot meet the growing demand for internet-connected devices.
Complex Setup: Requires manual configuration or DHCP, which can be error-prone.
Inefficient Routing: Larger, complex headers slow down data processing.
Weak Security: No built-in security; extra measures are needed.
Poor QoS Support: Limited ability to prioritize traffic, affecting video/voice quality.
Packet Fragmentation: Routers may split packets, causing inefficiency and possible data loss.
Broadcast Overhead: Uses broadcasting, which increases unnecessary traffic and reduces performance.

The recent Version of IP IPv6 has a greater advantage over IPv4. Here are some of the mentioned benefits:

Larger Address Space: IPv6 uses 128-bit addresses (vs. 32-bit in IPv4), allowing many more devices to connect.
Improved Security: IPv6 has built-in features like data authentication and encryption, making connections safer..
Simpler Header: IPv6 has a streamlined header, improving speed and reducing processing cost.
Better QoS Support: IPv6 provides stronger Quality of Service, improving video, audio, and website performance.
Mobile-Friendly: IPv6 offers better, faster, and more secure support for mobile connections.

Switching From IPV4 to IPV6 : To switch from IPv4 to IPv6, there are several strategies:

Dual Stacking : Devices can use both IPv4 and IPv6 at the same time. This way, they can talk to networks and devices using either version.
Tunneling : This method allows IPv6 users to send data through an IPv4 network to reach other IPv6 users. Think of it as creating a "tunnel" for IPv6 traffic through the older IPv4 system.
Network Address Translation (NAT) : NAT helps devices using different versions of IP addresses (IPv4 and IPv6) to communicate with each other by translating the addresses so they understand each other.

The below table shows the difference between the IPV4 and IPV6 addressing:

Feature	IPv4	IPv6
Address Length	32-bit address	128-bit address
Address Format	Decimal format (e.g., 192.168.0.1)	Hexadecimal format (e.g., 2001:0db8::1)
Configuration	Manual and DHCP configuration	Auto-configuration and renumbering supported
Connection Integrity	End-to-end integrity is unachievable	End-to-end integrity is achievable
Security	No built-in security; external tools like IPSec needed	IPSec is built-in for encryption and authentication
Fragmentation	Performed by sender and routers	Performed only by the sender
Flow Identification	Not available	Uses Flow Label field in header for packet flow identification
Checksum Field	Present	Not present
Transmission Scheme	Supports broadcast	Uses multicast and anycast; no broadcast
Header Size	Variable: 20–60 bytes	Fixed: 40 bytes
Conversion	Can be converted to IPv6	Not all IPv6 addresses can be converted to IPv4
Field Structure	4 fields separated by dots (.)	8 fields separated by colons (:)
Address Classes	Has address classes (A, B, C, D, E)	No concept of address classes
VLSM Support	Supports Variable Length Subnet Mask (VLSM)	Does not support VLSM
Example	66.94.29.13	2001:0000:3238:DFE1:0063:0000:0000:FEFB

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Computer Network Basics