IPv4 vs IPv6
Understanding the differences between IPv4 and IPv6
Table of Contents
IPv4 vs IPv6
IPv4 and IPv6 differ in: address space (IPv4 uses 32-bit addresses providing ~4.3 billion addresses, IPv6 uses 128-bit addresses providing virtually unlimited addresses), address format (IPv4 uses dotted decimal notation like 192.0.2.1, IPv6 uses hexadecimal notation like 2001:db8::1), address exhaustion (IPv4 addresses are running out, IPv6 provides unlimited addresses), features (IPv6 includes built-in security, auto-configuration, improved routing), and adoption (IPv4 is still dominant, IPv6 adoption is increasing).
IPv6 is the successor to IPv4, designed to address IPv4 address exhaustion and provide improved networking features. Learn more about IP addresses.
Address Space
IPv4 Address Space
IPv4 uses 32-bit addresses, providing approximately 4.3 billion unique addresses (2^32). IPv4 address space is nearly exhausted, requiring solutions like NAT (Network Address Translation) to extend address availability.
IPv6 Address Space
IPv6 uses 128-bit addresses, providing 340 undecillion unique addresses (2^128) - virtually unlimited address space. IPv6 eliminates address exhaustion concerns.
Address Exhaustion
IPv4 address exhaustion is a major concern - available IPv4 addresses are running out. IPv6 addresses this by providing vast address space.
NAT and IPv6
IPv4 often requires NAT to share addresses. IPv6 eliminates need for NAT due to abundant address space, enabling direct device addressing.
Address Format
IPv4 Format
IPv4 addresses use dotted decimal notation: four octets separated by dots (e.g., 192.0.2.1). Each octet ranges from 0-255.
IPv6 Format
IPv6 addresses use hexadecimal notation: eight groups of four hexadecimal digits separated by colons (e.g., 2001:0db8:0000:0000:0000:0000:0000:0001). Leading zeros can be omitted, and consecutive zero groups can be compressed (e.g., 2001:db8::1).
Format Examples
- IPv4:
192.0.2.1 - IPv6:
2001:db8::1 - IPv6 (full):
2001:0db8:0000:0000:0000:0000:0000:0001
Readability
IPv4 addresses are shorter and more readable. IPv6 addresses are longer but provide compression mechanisms for readability.
Key Differences
Address Size
- IPv4: 32-bit addresses
- IPv6: 128-bit addresses
Address Space
- IPv4: ~4.3 billion addresses
- IPv6: 340 undecillion addresses
Features
- IPv4: Basic IP functionality
- IPv6: Built-in security (IPsec), auto-configuration, improved routing, flow labeling
Header Size
- IPv4: 20-byte header (variable)
- IPv6: 40-byte header (fixed)
Fragmentation
- IPv4: Routers can fragment packets
- IPv6: Only source can fragment
Adoption and Compatibility
Current Adoption
IPv4 is still dominant, but IPv6 adoption is increasing. Many networks support both IPv4 and IPv6 (dual-stack configuration).
Dual-Stack
Dual-stack networks support both IPv4 and IPv6 simultaneously, enabling gradual migration and compatibility.
Migration
Organizations are migrating to IPv6 to address IPv4 exhaustion and leverage IPv6 features. Migration can be gradual using dual-stack.
Compatibility
IPv4 and IPv6 are not directly compatible - translation mechanisms (NAT64, tunneling) enable communication between IPv4 and IPv6 networks.
Future
IPv6 is the future of internet addressing, providing unlimited address space and improved networking features.
