IPv4 vs IPv6 and the missing IPv5

The time of IPv1, IPv2, and IPv3 is long gone. Here you will see an in-depth comparison between the IP protocols: Ipv4 vs IPv6. You will learn how it is possible that we are still using the ancient IPv4, why IPv6 is the future, and what happened to the missing IPv5. Let us get started! 

What is IP (Internet Protocol)? 

IP (Internet Protocol) is the internet protocol that we all use. It is an essential communication protocol that rules the transmission of data packets over computer networks, including the Internet. The IP provides the addressing and routing mechanisms necessary for devices to communicate with each other and exchange data across interconnected networks. 

In other words, the IP allows our devices to connect to the Internet. It is a description, a set of rules that determine the way data goes from a client, all the routes to the host and back. The IP addresses identify all connected devices. They are unique. 

In the beginning, the IP protocol was part of another one – TCP/IP. It took 3 revisions of this protocol for the IP to be separated from the TCP/IP. The first independent IP was version 4 – IPv4. 

What is IPv4? 

You are familiar with the IPv4, or Internet Protocol version 4. It is the fourth iteration of the Internet Protocol (IP) suite and the most widely deployed protocol for Internet communication. An IPv4 looks like this – 157.240.20.15. This numerical sequence consists of 32 bits, divided into four groups of numbers (octets) between 0 and 254, separated by dots. IPv4 addresses are hierarchical, with different classes (A, B, C) and subnets used to allocate address space efficiently and support network growth. In total, there are 4 294 967 296 IPs! A tremendous number, don’t you think so? Yet, when we think about how many devices there are, and most of them are connected to the Internet, we can see that it is not enough. 

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IPv4 packets consist of a header and a payload. The header contains essential information for routing and delivering packets, including source and destination IP addresses, packet length, time-to-live (TTL) value, and protocol type, for example, TCP or UDP. The payload carries the actual data being transmitted, such as email messages, web pages, or multimedia content. 

IPv4 uses routers to forward data packets from the source to the destination across interconnected networks. Routers examine the destination IP address of every packet and use routing tables to determine the optimal path for packet delivery. IPv4 routing protocols, such as Border Gateway Protocol (BGP) and Interior Gateway Protocols (IGPs), facilitate routing decisions and route exchange between routers. 

One of the key features of IPv4 is the Network Address Translation (NAT), which allows multiple devices within a private network to share a single public IP address. NAT translates private IP addresses used within the local network to a single public IP address visible on the Internet, enabling devices on the private network to access online resources while conserving public IP address space. Explained simply, at your home, each of your devices – smartphones, tablets, laptops, etc has unique IP address on your home network. But they all share the same public IP address, thanks to the NAT translation your router performs.  

IPv4 was developed in the early 1980s and has been the primary protocol used for several decades. The Internet providers use clever ways to reuse the IPs, but this can’t last forever. Here the new standard kicks in. 

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What is IPv6? 

IPv6, or Internet Protocol version 6, is the newest version of the Internet Protocol (IP) suite, designed to succeed IPv4 and address its limitations. IPv6 was created considering several enhancements over IPv4, including a significantly larger address space, improved network security, better support for mobile devices and Internet of Things (IoT) devices, and simplified network configuration and management. 

The IPv6 uses 128-bit addressing, while IPv4 uses 32-bit addressing. A bit of an overkill, but that way this standard can last a long, long time. See this example of an IPv6 address: “2001:0db8:0000:0041: 0200:8a2e: 0370:7344”. Here the groups became more – 8 octets. Each of them has 4 hex (hexadecimal) digits and they are separated by colons. That way there are plenty more combinations. To be exact, 1028 more times than IPv4! It ensures an abundant supply of addresses -approximately 340 undecillion unique addresses, to accommodate the growing number of internet-connected devices worldwide. 

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IPv6 addresses are hierarchically structured and support both global unicast addresses for internet communication and unique local addresses for local network communication. 

IPv6 packets have a simplified header format compared to IPv4, reducing overhead and improving packet processing efficiency. The IPv6 header includes essential fields such as source and destination IP addresses, packet length, traffic class, flow label, and next header type. IPv6 also supports extension headers for additional features such as fragmentation, security, and mobility. 

IPv6 routers use routing protocols such as Routing Information Protocol version 6 (RIPng), Open Shortest Path First version 3 (OSPFv3), and Border Gateway Protocol version 6 (BGP-4+) to exchange routing information and maintain routing tables. IPv6 routing protocols are designed to support the larger address space of IPv6 and enable efficient packet forwarding across interconnected networks. IPv6 is the improved routing without fragmentation of packets. 

IPv6 includes built-in support for stateless address auto-configuration (SLAAC), allowing devices to automatically configure their IPv6 addresses and network settings without the need for manual configuration or DHCP servers. SLAAC simplifies network setup and management, especially in dynamic and rapidly changing environments such as mobile networks and IoT deployments. 

IPv6 incorporates security features such as Internet Protocol Security (IPsec) as an integral part of the protocol suite. IPsec provides authentication, encryption, and integrity protection for IPv6 communication, enhancing network security and privacy. With IPv6, security mechanisms are mandated by default, unlike IPv4, where they are optional and often implemented at higher protocol layers. 

IPv6 includes support for mobile devices and roaming users through features such as Mobile IPv6 (MIPv6) and Neighbor Discovery Protocol (NDP). MIPv6 enables seamless mobility and transparent handover of IP connections as devices move between different networks. NDP facilitates address resolution, neighbor discovery, and router discovery in IPv6 networks. 

IPv6 supports enhanced quality of service (QoS) mechanisms for prioritizing and managing network traffic based on predefined criteria such as traffic type, source, destination, and service level agreements (SLAs). QoS features in IPv6 enable improved network performance, reliability, and efficiency for time-sensitive applications such as voice and video streaming. 

IPv4 vs IPv6 comparison 

We already have mentioned some essential differences between IPv4 and IPv6 but let us go even deeper! The following comparison will completely clarify the picture Ipv4 vs IPv6. 

Security, IPv4 vs IPv6 

IPv4: Security features like IPSec are optional and not widely deployed. 

IPv6: IPSec is part of the IPv6 protocol suite and is often implemented by default, enhancing security for communications. 

Address space, IPv4 vs IPv6 

IPv4: 32-bit address space, allowing for approximately 4.3 billion unique addresses. 

IPv6: 128-bit address space, providing an enormous number of unique addresses (approximately 3.4 × 10^38), which helps accommodate the growing number of devices connected to the internet. 

Address representation, IPv4 vs IPv6 

IPv4: Uses decimal dotted notation (example, 192.0.2.1). 

IPv6: Uses hexadecimal notation separated by colons (example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334). 

Address configuration, IPv4 vs IPv6 

IPv4: Addresses are often configured manually or via DHCP (Dynamic Host Configuration Protocol). 

IPv6: Addresses can be configured manually, via stateful DHCPv6, or through stateless address autoconfiguration (SLAAC). 

Header format, IPv4 vs IPv6 

IPv4: Simple header format with fields such as version, header length, type of service, total length, identification, flags, fragment offset, time to live, protocol, header checksum, source address, and destination address. 

IPv6: Simplified header format with fields such as version, traffic class, flow label, payload length, next header, hop limit, source address, and destination address. 

Header size, IPv4 vs IPv6 

IPv4: Fixed header size of 20 bytes, not including options. 

IPv6: Fixed header size of 40 bytes, with options handled through extension headers. 

Checksum, IPv4 vs IPv6 

IPv4: Includes a checksum field in the header to detect errors in the packet. 

IPv6: The checksum field is removed from the header. Error detection is handled at higher layers. 

Multicasting, IPv4 vs IPv6 

IPv4: Multicast is optional and realized through class D addresses. 

IPv6: Multicast is an integral part of the protocol, and multicast addresses are defined within the address space. 

Network configuration, IPv4 vs IPv6 

IPv4: Network Address Translation (NAT) is commonly used to conserve IPv4 address space. 

IPv6: NAT is less necessary due to the vast address space of IPv6, enabling every device to have a globally unique address. 

Transition mechanisms, IPv4 vs IPv6 

IPv4: Various transition mechanisms like dual stack, tunneling (example: 6to4 and Teredo), and translation (example NAT64) are used to facilitate the coexistence of IPv4 and IPv6 networks. 

IPv6: Transition mechanisms are primarily focused on facilitating the migration from IPv4 to IPv6. 

Speed, IPv4 vs IPv6 

There’s no inherent difference between IPv4 and IPv6. Both protocols can achieve similar speeds given the same network conditions and hardware. 

What happened to IPv5? 

While reading this IPv4 vs IPv6, you perhaps wondered what about IPv5? Why is it missing? Well, its story is a sad one because the IPv5 did not make it. The Internet Stream Protocol (ST) or IPv5 was developed in the late 1970s by the Internet Engineering Task Force (IETF) as an experimental protocol to support real-time streaming applications such as multimedia and audio/video conferencing over the Internet. 

Its design included innovative features such as multicast transmission to efficiently distribute streaming media content to multiple recipients simultaneously, quality of service (QoS) support, enhanced error recovery mechanisms, and prioritizing traffic based on the requirements of real-time applications. 

Despite its promising features, IPv5 faced several challenges that limited its adoption and deployment. For instance: 

• Compatibility issues. IPv5 was not backward compatible with IPv4, requiring significant changes to existing networking infrastructure and devices. 
• Lack of standardization. IPv5 was not standardized by the IETF or other standardization bodies, leading to fragmentation and inconsistency in its implementation. 
• Limited use cases. The demand for real-time streaming applications was not as widespread in the 1970s and 1980s as it is today, limiting the relevance and applicability of IPv5.  
• 32-bit addresses. The worst part was that IPv5 used 32-bit addresses. Not sufficient at all.   

• Lack of adoption. Due to its experimental nature and limited deployment, IPv5 failed to gain traction among network operators, service providers, and equipment manufacturers. 
• Emergence of IPv6. As the limitations of IPv4 became a big concern, the Internet community shifted its focus to developing IPv6 as a long-term solution to address the address space exhaustion and scalability issues of IPv4. 
• Transition challenges. The transition from IPv4 to IPv6 meant significant challenges in terms of compatibility, interoperability, and migration, making it difficult for IPv5 to gain momentum as an alternative protocol. 

This way, IPv5 never got to be a real standard and died during development. It was not much of an improvement compared to IPv4. It was regarded as a streaming protocol and got a few years of development, with the last version being ST2 (the second version). In the end, it was abandoned together with the name. Developers focused all their efforts on the next standard, the IPv6. 

Conclusion 

This IPv4 vs IPv6 was conclusive, IP have no v6 offers numerous advantages over IPv4. As the global Internet continues to grow and evolve, IPv6 adoption is essential for ensuring the scalability, security, and interoperability of network infrastructure and services in the future. 

The only reason we have not switched completely to IPv6 is the cost of upgrading. ISPs are doing it but at a slow pace. As of February 2024, Google’s statistics show IPv6 availability of its global user base at around 39–45% depending on the day of the week (greater on weekends). Adoption is uneven across countries and Internet service providers. 

IPv6 will replace IPv4 forever. It will just need some time after which it will be the only IP standard for exceedingly long.