The Internet has become an indispensable communication medium due to the rapid growth of devices connected to it. The underlying network protocol that makes this growth possible is Internet Protocol (IP). IP allows different types of networks to communicate with each other by assigning unique addresses to each device.
The first version of IP, IPv4, was developed in the 1970s under the ARPANET project. IPv4 has been the foundation that enabled the internet to scale up exponentially over the past few decades. However, exponential internet growth led to IPv4 address exhaustion. To allow further expansion of the internet, Internet Protocol version 6 (IPv6) was standardized in the 1990s as the successor to IPv4.
This article provides an in-depth, technical comparison of the differences between IPv4 and IPv6. We’ll cover the history of each protocol, compare their technical specifications, advantages/disadvantages, adoption trends, and future outlook.
A Brief History of IPv4 and IPv6
The Origin of IPv4
The first documented account of a networked computer system is the ARPANET project funded by the U.S. government’s Advanced Research Projects Agency (ARPA) in the late 1960s. The objective was to connect computers at various universities and allow remote login.
To enable communication between these computers, the Network Working Group (NWG) devised a networking protocol called NCP (Network Control Protocol) in 1970. This allowed basic communication between hosts on the ARPANET network.
By 1973, limitations with NCP’s host-to-host communications model led Vint Cerf and Bob Kahn to design an improved protocol. This new protocol, called Transmission Control Protocol (TCP), enabled peer-to-peer connectivity between network hosts.
TCP was further refined and adopted as the standard ARPANET protocol by January 1983. This version evolved into the Internet Protocol suite, more commonly known today as TCP/IP. The “IP” component, called Internet Protocol Version 4 (IPv4), handles addressing and routing data packets between hosts.
So in summary, IPv4 traces back its roots to the experimental era of ARPANET in the 1970s. It adopted the still prevalent Internet Protocol suite by 1983 when ARPANET transitioned to using TCP/IP permanently.
Motivation for Developing IPv6
Since IPv4 was developed in an era when the internet was still in its infancy, the protocol had some inherent limitations that could not have been foreseen. The most glaring limitation that prompted replacing IPv4 is its shortage of available addresses.
IPv4 uses 32-bit addresses, which limits unique address assignments to around 4.3 billion devices. Initially, 4.3 billion addresses seemed sufficient. However, with the rapid global adoption of internet-enabled devices and the Internet of Things (IoT), we‘ve already exhausted the entire IPv4 range.
Some other factors motivating the creation of IPv6 in the 1990s were:
- Lack of flexibility in IPv4 packet header format
- Absence of authentication and privacy capabilities
- Need for better support for QoS and real-time traffic
- Obligation for manual host configuration and address management
Considering these motivations, the Internet Engineering Task Force (IETF) began developing the next generation of IP in the early 1990s. After many revisions, RFC 2460 formally defined IPv6 in 1998.
So in a nutshell, IPv6 originated from the need for a more robust internet protocol that could support the future growth of networks well into the 21st century and beyond. Next, we’ll compare the technical composition and capabilities of IPv4 and IPv6.
Key Differences Between IPv4 and IPv6
While IPv4 and IPv6 perform the same core function of transporting packets across interconnected networks, they differ significantly in the technical details of how they achieve this communication.
Below we highlight some of the major technical differences between the two protocols.
Address Space
The most apparent and impactful difference between IPv4 vs IPv6 lies in the address space supported.
IPv4: Uses 32-bit addresses providing approximately 4 billion unique IP addresses.
IPv6: Uses 128-bit addresses providing approximately 340 trillion trillion trillion unique IP addresses.
The mammoth address space with IPv6 ensures that we will likely never run out of IP addresses ever again!
Address Representation
Along with the size of the addresses, IPv4 and IPv6 use different representations for their addresses:
IPv4: Decimal notation separated by dots (.)
- Example:
192.168.1.5
- Example:
IPv6: Hexadecimal notation separated by colons (:)
- Example:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
- Example:
Additionally, IPv6 allows abbreviation of consecutive sections of zeros with double colons (::). So the above address can be shortened to:
2001:db8:85a3::8a2e:370:7334
This colon-hexadecimal notation makes IPv6 addresses look quite distinct from IPv4 dotted-decimal addresses.
Packet Header Format
The packet header carries control information about each data packet sent over the network. IPv4 and IPv6 packet headers have some similarities but also many differences:
IPv4 vs IPv6 packet header format. Source: NetworkEncyclopedia
Key differences in header format:
Fixed size vs variable size – IPv6 has a fixed 40-byte header, simpler for faster routing. IPv4 header is variable from 20-60 bytes.
Number of fields – IPv6 header has just 8 fields vs 13 fields for IPv4. The simplified IPv6 header makes packet processing more efficient.
Fragmentation – IPv4 allows fragmentation while IPv6 doesn’t fragment packets en-route needing reassembly at destination.
Checksum – IPv4 has the header checksum field for error checking. IPv6 has removed this field for better performance.
Options – IPv6 options are only specified in extension headers rather than the main IPv6 header.
So in summary, IPv6 streamlines things by simplifying the packet header to just absolutely essential information.
Transition Mechanisms from IPv4 to IPv6
Since IPv4 and IPv6 are not interoperable, certain transition mechanisms allow the coexistence and gradual transition from IPv4 to IPv6 networks:
Dual-stack – Network devices like routers run both IPv4 and IPv6 protocol stacks to support connectivity over either type of network.
Tunneling – Used to transport IPv6 packets over existing IPv4 networks that don’t yet support IPv6 routing.
Configuration and Management
IPv6 aimed to improve upon manual configuration and address management methods required for IPv4 networks:
Address auto-configuration – IPv6 supports plug n play connectivity by allowing hosts to automatically configure IP addresses.
Simplified management – Due to the ample availability of IPv6 addresses, address conservation techniques like NAT, VLSM etc. are not required.
Multicasting & Broadcasting
IPv6 drops support for traditional IPv4 broadcast in favor of more modern multicasting communication. This allows more efficient streaming and messaging to multiple hosts.
Security
IPv6 was designed with integrated security, authentication, and privacy features lacking in IPv4. For instance, IPSec support comes built-in as standard rather than via extensions like with IPv4.
Packet size
The maximum transmission unit (MTU), which determines the largest packet size transmittable without fragmentation, is:
- IPv4 – 576 bytes
- IPv6 – Substantially larger at 1280 bytes without considering the IPv6 extension headers
So IPv6 can carry much larger packet payloads improving communication efficiency and throughput.
Anycast addressing
IPv6 introduces anycast addressing, allowing a device to be addressable on multiple interfaces. This helps with load distribution, redundancy, and service availability.
These are some of the significant technical differences between the two IP protocols. Next, we‘ll compare the advantages and disadvantages of IPv4 vs IPv6.
Advantages and Disadvantages IPv4 vs IPv6
Below we summarize some of the key advantages and disadvantages of IPv4 and IPv6 stacked up against each other:
IPv4 pros:
- Mature, proven, and known technology
- Requires less overhead than IPv6 due to smaller packet headers
- Familiar standards and addressing for network administrators
IPv4 cons:
- Limited, depleted address space
- Manual configuration required
- Lack of built-in security and other advanced features
- Absence of multicast/anycast support
IPv6 pros:
- Virtually unlimited address space
- Faster routing due to simplified fixed-length header
- Built-in security and authentication
- Better support for high-bandwidth applications
- Simplified network management
- Multicast and anycast built-in
IPv6 cons:
- Partial adoption leading to interoperability issues
- Loss of network administrators’ familiarity
- Larger packet header size than IPv4
- Possible issues due to limited IPv6 exposure
So in summary, IPv6 overcomes the deficiencies of IPv4 providing a more robust and future-proof standard. But until IPv6 gains very high adoption, interoperability issues and learning curves remain a reality.
Current Adoption Trends
Now that we‘ve compared the technical composition and merits of IPv4 vs IPv6, let‘s take a look at what percentage of internet traffic uses each of these protocols as of 2023.
According to Google‘s IPv6 statistics, global IPv6 adoption crossed the 50% threshold for the first time in July 2022.
As of January 2023, IPv6 handles around 54% of global internet traffic while IPv4 continues to handle the remaining 46% share.
Among regions with the highest IPv6 adoption percentage are:
- Belgium – 69%
- Germany – 68%
- Greece – 65%
- United States – 63%
So while we still have a ways to go for global adoption of IPv6, we’ve passed the halfway point with over 50% of internet traffic now leveraging IPv6 routing.
Business networks too are migrating from IPv4 to IPv6 with providers like AT&T, Verizon, T-Mobile having enabled IPv6 connectivity. Major cloud service providers (Azure, AWS, Google Cloud) today fully support both IPv4 and IPv6 for their public cloud infrastructure.
As IPv6 adoption continues rising exponentially across networks small and large, we anticipate hitting approximately 80% global adoption by 2025 according to projections by Cisco.
The Outlook for IPv4 vs IPv6 Coexistence
Given the current adoption trends, will IPv6 eventually completely supersede IPv4? Or will both protocols continue to coexist far into the future?
Realistically, the two protocols will operate in parallel for decades to come instead of IPv6 instantly replacing IPv4 universally.
The main reason being – migrating the IPv4 infrastructure that powers 46% of the internet currently is an extremely complex undertaking. Various technical and economic constraints have slowed the transition even though IPv6 standardization happened over two decades ago!
However, IPv6 usage will continue its growth trajectory until it handles nearly all internet traffic globally. The exception would be some private legacy networks that retain IPv4 due to feasibility constraints. On the public internet and for new networks though, IPv6 will become the de facto standard that allows us to connect billions more devices and users online.
So in summary, although IPv4 has served us well for nearly 40 years powering internet growth so far, its days are now numbered. IPv6 adoption will accelerate leading it to become the predominant internet protocol over the next decade.
Conclusion
We‘ve covered a wide-ranging comparison including the history, motivation for creating IPv6, key technical differences between IPv4 and IPv6, their relative advantages/disadvantages, current adoption trends, and outlook for the future.
Some key conclusions are:
- Global IPv6 adoption crossed 50% in mid-2022 and will likely hit 80% by 2025
- IPv4 lacks capacity to cope with future internet growth while IPv6 provides an almost infinite supply of IP addresses
- IPv6 modernizes internet communication with built-in security, simplified headers, configuration management, anycast/multicast capabilities etc. absent in IPv4
- Both protocols will coexist for a long time until IPv6 overtakes to become the dominant internet protocol
So in closing, organizations would do well to enable IPv6 connectivity now even if they plan to run IPv4 and IPv6 side-by-side for years to come. Eventually, IPv6 will supersede IPv4 similar to how IPv4 itself overtook older standards like IPX/SPX. Making the gradual transition to IPv6 future-proofs networks to continue leveraging all the latest internet technologies for decades ahead!
