Complete Communications Engineering

What is IPv6?

IPv6, or Internet Protocol version 6, stands as the latest iteration of the Internet Protocol (IP). It was developed by the Internet Engineering Task Force (IETF) and reached draft standard status in 1998, later being ratified as an internet standard in 2017. IPv6 employs 128-bit addresses, providing a vast address space for devices. These addresses serve as unique identifiers crucial for routing data across the internet.

IPv6 Header Diagram

Why IPv6?

IPv6 emerged from the limitations of IPv4, which could no longer accommodate the growing number of devices being connected to the internet. With IPv4’s address space nearly exhausted, it was evident that a new IP version was necessary. In November 2019, RIPE NCC’s announcement of IPv4 address exhaustion further underscored the urgency of transitioning to IPv6. IPv6 offers a vastly expanded address space, enabling the continued growth of the internet and ensuring that the world remains connected.

IPv6 Compared to IPv4

IPv4 and IPv6 differ significantly in several key aspects. IPv4 uses 32-bit addresses, limiting it to 2^32 addresses, while IPv6 employs 128-bit addresses, offering a vast 2^128 address space. IPv6 addresses are represented in hexadecimal format, grouped in 8 segments and separated by colons, while IPv4 addresses are in decimal format separated by periods.

Multicasting is a fundamental aspect of IPv6 but optional in IPv4. IPv6 also includes built-in payload encryption capabilities, unlike IPv4, which requires additional implementations like IPsec for encryption. Address configuration varies, with IPv4 supporting manual and DHCP configuration, while IPv6 supports auto-configuration and renumbering. IPv6 also handles fragmentation differently, using end-to-end fragmentation, whereas IPv4 requires intermediate routers to fragment large datagrams. Additionally, RIP (Routing Information Protocol) is supported in IPv4 but not in IPv6. IPv6’s resolution of IP to MAC addresses uses multicast Neighbor Solicitation, while IPv4 uses broadcast ARP. A notable IPv6 feature is the use of solicited-node multicast addresses by the Neighbor Discovery Protocol for various functions, including Duplicate Address Detection (DAD).

Conceptualizing IPv6 Address Space

To fully grasp the vast address space of IPv6, consider the following:

If you were to count out loud every possible IPv4 address starting from (assuming one address spoken per second), it would take approximately 136 years.

If you were to count out loud every possible IPv6 address starting from 0000:0000:0000:0000:0000:0000:0000:0000 (assuming one address spoken per second), it would take approximately 1.08 × 1e+27 years!

Here is a live counter to visualize the address space:

IPv6 and IPv4 Address Generators

Upsides and Downsides

IPv6 offers several advantages over IPv4. It allows for hierarchical address allocation, which aids in route aggregation and helps limit the expansion of routing tables across the Internet. IPv6 is also more compatible with mobile networks and supports larger payloads compared to IPv4. Additionally, the vast address range of IPv6 eliminates the need for subnetting.

However, IPv6 has its drawbacks. Its longer, alphanumeric addresses can be harder to remember. While IPv6 eliminates the need for NAT (Network Address Translation), which can anonymize devices, NAT has been found to have some useful anonymization effects. Moreover, transitioning to IPv6 requires every router in a network to change, which has made the replacement of IPv4 challenging due to the existing infrastructure, code, and endpoints that would need upgrades or replacements to support IPv6.

How IPv6 affects VoIP

IPv6 brings significant advantages to VoIP (Voice over Internet Protocol) systems. By eliminating the need for NAT (Network Address Translation), IPv6 removes the possibility of “one-way-voice” issues that can occur due to NAT complications. IPv6 simplifies end-to-end security configuration by allowing for the configuration of security parameters at the endpoints, eliminating the need to configure security parameters for every device in between. IPv6 also includes header fields reserved for Quality of Service (QoS) mechanisms, which help ensure the orderly and timely delivery of packets belonging to the same voice conversation or flow. However, it’s worth noting that compared to IPv4, IPv6 headers are larger, which can impact VoIP performance as VoIP packets are typically small. The larger header size of IPv6 effectively increases the size of VoIP packets, potentially affecting bandwidth usage.

IPv6 Mandated by U.S. Government

The U.S. government is actively mandating the transition to IPv6 for all Department of Commerce (DoC) information systems by 2025, as outlined in the Office of Management and Budget (OMB) memorandum, M-21-07. This mandate requires that a certain percentage of IP-enabled assets on Federal networks operate in IPv6-only environments by specific deadlines: 20% by the end of FY 2023, 50% by the end of FY 2024, and 80% by the end of FY 2025. The memorandum also calls for the identification and justification of Federal information systems that cannot be converted to IPv6, along with a schedule for replacing or retiring these systems. This mandate underscores the government’s commitment to IPv6 adoption and the modernization of its information systems to meet current and future technology requirements.

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