IPv4 vs. IPv6

In this blog post, we will review IPv4 vs. IPv6 and see how they differ in addressing scalability, security, compatibility, and adoption. We’ll also discuss some advantages and difficulties of switching from IPv4 to IPv6.

A vast network of interconnected devices called the Internet uses the Internet Protocol (IP) to communicate. Data is divided into packets by IP, which also gives them addresses and directs them to their intended locations. The Internet as we know it would not exist without IP.

IP, however, is not a static protocol that never changes. It changes over time in response to the challenges and shifting demands of the Internet. IPv4, released in 1983 and served as the Internet’s foundation for many years, is the version of IP that is currently most used. 

However, IPv4 has some limitations that make it unable to keep up with the Internet’s and its users’ rapid expansion. This is why a more recent version of IP, IPv6, was created and is gradually being embraced by more networks and devices.

Now let’s move to this IPv4 vs. IPv6 comparison step by step.

IPv4: The Old Guard

The fourth version of the Internet Protocol, IPv4, is also the most widely used. It uses 32-bit addresses, such as, expressed in dotted decimal notation. Four octets (8 bits) make up each address. Dots separate them. Each octet can have a value between 0 and 255.

Up to 4.3 billion unique addresses can be used in the 32-bit IPv4 address space. It sounds like a lot until you consider how many devices are connected to the Internet. By 2025, there will likely be 22 billion connected devices, up from an estimated 10 billion in 2020, according to Statista. This indicates that there aren’t enough IPv4 addresses to give each device that requires one unique address.

Various methods to prolong the use of IPv4 have been developed to address this issue, including:

Network Address Translation (NAT): This method uses private addresses from a local network to let multiple devices share a single public IPv4 address. NAT devices translate private addresses into public ones and vice versa, serving as translators between the local network and the Internet.

Classless Inter-Domain Routing (CIDR): This technique divides the IPv4 address space into smaller, more adaptable units known as subnets. By minimizing wastage and fragmentation, CIDR enables more effective utilization of the available addresses.

Dynamic Host Configuration Protocol (DHCP): This protocol allows IP addresses to be assigned and managed automatically within a network. When no longer required, DHCP servers can reclaim IP addresses leased to devices for a predetermined time.

Although these methods have assisted in delaying the exhaustion of IPv4 addresses, they are not long-term fixes. They also bring about some negatives, such as:

Complexity and overhead: NAT devices and DHCP servers add extra layers of processing and configuration to the network, affecting performance and reliability.

Security risks: NAT devices can obscure the source and destination of packets, making it harder to trace malicious traffic or enforce firewall rules. DHCP servers can also be vulnerable to attacks that spoof or hijack IP addresses.

End-to-end connectivity issues: NAT devices can break some applications that rely on direct communication between devices, such as peer-to-peer file sharing or video conferencing.

IPv6: The New Frontier

The sixth iteration of the Internet Protocol, IPv6, is IPv4’s replacement. It was created to get around IPv4’s restrictions and support the Internet’s ongoing development. It uses 128-bit addresses, like 2a00:5a60:85a3:0:0:8a2e:370:7334, expressed in hexadecimal colon notation. Eight groups of four hexadecimal digits (16 bits) make up each address; colons separate these groups, and each group can have a value between 0000 and ffff.

IPv6’s 128-bit address space can accommodate up to 340 undecillion (340 followed by 36 zeros) unique addresses, which is more than enough to give each atom on Earth an IP address. Because each device can have its public address, IPv6 networks do not require NAT or DHCP.

Some of the features and advantages of IPv6

Simplified header format: Unlike IPv4’s variable-length header, IPv6’s fixed-length header of 40 bytes is more straightforward and effective. In addition, fields like checksum, fragment offset, and header length that are no longer required or redundant are dropped in favor of IPv6.

Improved routing and forwarding: To reduce the size and complexity of routing tables and increase the speed and scalability of packet forwarding, IPv6 supports hierarchical and aggregatable addressing. Additionally, IPv6 supports multicast and anycast addressing, allowing for the swift delivery of packets to a few nearby or multiple destinations.

Enhanced security and privacy: IPsec, a protocol suite that offers IP packet integrity, authentication, and encryption protection, has built-in support in IPv6. In IPv4, IPsec is optional; in IPv6, it is required. Additionally, IPv6 supports temporary and random addresses, which can shield devices from tracking and spoofing.

Seamless mobility and autoconfiguration: Thanks to functions like neighbor discovery and mobile IPv6, devices can switch between networks without changing their IP addresses or losing their connections. Due to features like stateless address autoconfiguration (SLAAC) and router advertisements, IPv6 also enables devices to automatically configure their IP addresses and other parameters without needing DHCP servers.

IPv4 vs. IPv6: Addressing and Scalability

The size and format of their addresses serve as the most glaring distinction when comparing IPv4 vs. IPv6. As we’ve seen, 32-bit addresses are used by IPv4 while IPv6 uses 128-bit addresses. The number of addresses that can be used and the Internet’s scalability are both significantly impacted by this.

The number of unique addresses that IPv4 can support, up to 232 or 4.3 billion, needs to be increased to meet the demand for IP-connected devices now and in the future. The maximum number of unique addresses that IPv6 can support is 2128 or 340 undecillion, which is more than enough to give each device on the planet an IP address for the foreseeable future.

Consider each IPv4 address as a single grain of sand to understand the disparity in scale better. A big truck would be full of IPv4 addresses in total. Consider each IPv6 address as a single grain of sand. The entire Earth would be covered in IPv6 addresses.

The notation and visual representation of IPv4 and IPv6 addresses are other differences between the protocols. Dotted decimal notation, used by IPv4, is simple for humans to read and write but must be converted to binary by computers. The colon notation used by IPv6 is hexadecimal, which is easier for computers to read and write but more difficult for humans to read and write.

Examples of IPv4 vs. IPv6 addresses

is equivalent to the following binary representation:


The same address in hexadecimal notation would be:


The following IPv6 address:


is equivalent to the following binary representation:

00101010 00000000 01011010 01100000 10000101 10100011 00000000 00000000

00000000 00000000 10001010 00101110 00000111 00110000 01110011 00110100

The same address in decimal notation would be:


As you can see, hexadecimal notation is more concise and more accessible to manipulate than binary or decimal notation for long addresses.

IPv4 vs. IPv6: Security and Privacy

The degree of security and privacy the protocols offer for IP packets is another difference in comparing IPv4 vs. IPv6. Although both versions support IPsec and other encryption and authentication protocols, their implementation has some differences.

Because IPv4 lacks built-in support for IPsec, it must rely on third-party mechanisms or programs to secure IP packets. Since IPsec in IPv4 is optional, not all hardware or networks are compatible with it or consistently employ it. In IPv4 networks, this might result in compatibility problems or security holes.

Because IPv6 includes native support for IPsec, it has inbuilt security features in the IP layer. Since IPv6 requires IPsec, all systems and networks must be able to support and employ it by default. In IPv6 networks, this may lead to a more stable and secure environment.

NAT devices are another area where IPv4 and IPv6 security diverge. As we’ve seen, NAT hardware enables multiple devices to share a single public IP address in IPv4 networks. While doing so can reduce address space usage, it can also put connectivity and security at risk.

NAT devices can mask packet sources and destinations, making it more difficult to identify malicious traffic and enforce firewall policies. Peer-to-peer file sharing is one application that NAT devices can break because it depends on direct communication between devices.

The compatibility and transition between IPv4 and IPv6 are a third distinction between the two protocols. IPv4 and IPv6 are not directly interoperable because they use different address formats. This implies that some mechanisms are needed for communication networks and devices running various IP versions. Translation, tunneling, and dual-stack are a few of these mechanisms.

A network or device that supports dual stacking can switch between IPv4 and IPv6 simultaneously and supports both versions simultaneously. To navigate a network that does not help the native version of IP, an IPv6 packet is encapsulated within an IPv4 packet or vice versa. Translation is the process by which a device or service that serves as a bridge between IPv4 and IPv6 addresses maps an IPv4 address to an IPv6 address or vice versa.

IPv4 vs. IPv6: adoption and implementation

It seems in the competition IPv4 vs. IPv6 IPv4 is still ahead. Despite IPv6’s advantages over IPv4, its adoption and implementation have been unevenly distributed across various regions and industries. Google statistics show that as of August 2021, only 34% of users access Google services using IPv6, with the remainder continuing to use IPv4. 

According to statistics from the Internet Society, some nations have higher deployment rates of IPv6 than others, including Belgium (71%), India (63%), Germany (62%), and the US (48%). The accessibility of IPv6-compatible hardware, tools, software, content, and services, as well as the expense, difficulty, and incentives for migration, are some elements that influence its uptake.


The Internet Protocol has two versions, IPv4 and IPv6, each with unique features, advantages, and difficulties. Despite its continued widespread use, IPv4 has some restrictions that IPv6 resolves. The address space, security, privacy, and compatibility fall under this category. However, because of various technical and financial factors, IPv6 adoption and implementation have been uneven and slow in different regions and industries. The switch from IPv4 to IPv6 will take many years and necessitate cooperation from several other Internet ecosystem stakeholders.

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