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Operations and Management V6OPS Internet-Draft The document describes the reservation of an additional IPv6 address prefix for use in documentation. The reservation of a /20 prefix allows documented examples to reflect a broader range of realistic current deployment scenarios. Discussion Venues Discussion of this document takes place on the IPv6 Operations Working Group mailing list (v6ops@ietf.org), which is archived at . Source for this draft and an issue tracker can be found at .

Introduction introduced 2001:db8::/32, describing the use of the IPv6 address prefix 2001:DB8::/32 as a reserved prefix for use in documentation. The rationale for this reservation was to reduce the likelihood of conflict and confusion when relating documented examples to deployed systems. As the global deployment of IPv6 expands and evolves, individual IPv6 network deployment scenarios have also increased is size and diversity, and there is a requirement for documentation to reflect this increased diversity and scope. The original 2001:DB8::/32 reservation is inadequate to describe many realistic current deployment scenarios. Without this additional address allocation, then documentation address prefixes are drawn from address blocks already allocated or assigned to existing organizations or to well known ISPs, or drawn from the currently unallocated address pool. Such use conflicts with existing or future allocations or assignments of IPv6 address space. The reservation of a further /20 address prefix for documentation purposes avoids such conflicts.

Current Assignment and Allocation Data According to the allocation and assignment data published by the Regional Internet Registries, (https://ftp.ripe.net/pub/stats/ripencc/nro-stats/latest/nro-delegated-stats), in August 2023 some 25.9% of all 62,770 recorded allocations and assignments are larger than a /32 in size. The most common allocation or assignment size is a /29, used in 24.8% of cases. The four largest assignments made to end users have been /19s, but these allocations were made before the RIRs' address allocation policies moved away from the use of a fixed /48 site address prefix IPv6 address assignment policies, and in the foreseeable future its unlikely that individual networks require more than a /20. It is believed that a reservation of a /20 would cover the documentation needs as they relate the broad range of realistic network deployments.

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Security Considerations IPv6 addressing documents do not have any direct impact on Internet infrastructure security.

IANA Considerations IANA is to record the reservation of TBD::/20 in the IANA IPv6 Special-Purpose Address Registry. The Source, Destination, Forwardable, Globally Reachable and Reserved-by-Protocol fields should be recorded as False. There is no Termination Date for this entry.

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References To reduce the likelihood of conflict and confusion when relating documented examples to deployed systems, an IPv6 unicast address prefix is reserved for use in examples in RFCs, books, documentation, and the like. Since site-local and link-local unicast addresses have special meaning in IPv6, these addresses cannot be used in many example situations. The document describes the use of the IPv6 address prefix 2001:DB8::/32 as a reserved prefix for use in documentation. This memo provides information for the Internet community.

Acknowledgments The authors would like to acknowledge the valuable input from Xipeng Xiao, Chris Cummings, Russ White, Kevin Myers, Ed Horley, Tom Coffeen, and Scott Hogg