Blog ENG - Cisco - Post 7 2024
In the ever-evolving landscape of internet technology, the need for accurate and comprehensive documentation is paramount. RFC 9637 addresses this need by expanding the IPv6 documentation space, building upon the foundation laid by RFC 3849.
Introduction
RFC 3849 introduced the IPv6 address prefix 2001:db8::/32 for use in documentation, aiming to reduce conflicts and confusion when relating documented examples to real-world systems. However, as IPv6 deployment has grown, so has the diversity and scale of network scenarios. The original prefix is no longer sufficient to cover the breadth of modern deployments.
The Need for Expansion
With the global adoption of IPv6, network deployment scenarios have become more complex and varied. The original 2001:db8::/32 prefix is inadequate for many current deployment scenarios. Without additional address allocations, documentation prefixes might conflict with existing or future allocations, leading to potential issues.
The New Allocation
RFC 9637 introduces a new, larger prefix: 3fff::/20. This addition allows for more realistic and comprehensive documentation examples, reflecting a broader range of deployment scenarios. The reservation of this /20 prefix from the Global Unicast Address pool helps avoid conflicts with existing allocations.
Appropriate Use and Security
Documentation prefixes, including the new 3fff::/20, are intended solely for use in examples and configurations. They must not be used for actual traffic or globally advertised. These prefixes should be treated as bogons and filtered accordingly to prevent misuse.
Conclusion
RFC 9637 represents a significant step forward in ensuring that IPv6 documentation can keep pace with the evolving landscape of network deployments. By expanding the documentation space, it allows for more accurate and realistic examples, ultimately aiding in the smoother adoption and implementation of IPv6.