rfc-8425

IANA Considerations for IPv6 Neighbor Discovery Prefix Information Option Flags

O. Troan

date2018-07 streamIETF areaint wg6man statusPROPOSED STANDARD pages4 canonicalhttps://www.rfc-editor.org/rfc/rfc8425 doi10.17487/RFC8425

The Prefix Information Option (PIO) in the IPv6 Neighbor Discovery Router Advertisement message defines an 8-bit flag field; this field has two flags defined, and the remaining 6 bits are reserved (Reserved1). RFC 6275 defines a flag from this field without creating an IANA registry or updating RFC 4861. The purpose of this document is to create an IANA registry for the PIO flags. This document updates RFC 4861.

updates

rfc-4861 — Neighbor Discovery for IP version 6 (IPv6)

Extracted elements (7)

design-rationale §1

RFC 6275 defined the R (Router Address) flag in the PIO field without creating an IANA registry or updating RFC 4861, leaving flag allocation ungoverned. RFC 8425 remedies this gap by establishing a formal registry to manage future flag assignments.

ip, registry

interoperability-note §3

RFC 8425 updates RFC 4861 Section 4.6.2 to reference the new IANA registry for PIO flags, replacing the static reserved field description with a pointer to the managed registry.

normative-requirement §4 REQUIRED

Assignment of new flags in the PIO option header requires Standards Action as defined in RFC 8126.

registry, ip

protocol-element §2

The Prefix Information Option (PIO) in IPv6 Neighbor Discovery Router Advertisement messages contains an 8-bit flag field. Currently defined flags are: L (On-link Flag, bit 0), A (Autonomous Address Configuration Flag, bit 1), R (Router Address Flag, bit 2), and Reserved1 (bits 3-7).

registry §4

IANA created a new registry 'IPv6 Neighbor Discovery Prefix Information Option Flags' at http://www.iana.org/assignments/icmpv6-parameters. Initial entries: bit 0 = L (On-link Flag, RFC4861), bit 1 = A (Autonomous Address Configuration Flag, RFC4861), bit 2 = R (Router Address Flag, RFC6275), bits 3-7 = Reserved.

registry, ip, dns

security-consideration §5

This document has no security considerations; it solely establishes an IANA registry for existing PIO flags without changing protocol behavior.

security, ip

wire-format §2

The PIO flags field is an 8-bit field encoded as bits 0-7 within the Prefix Information Option header. Bits 0 (L), 1 (A), and 2 (R) are assigned; bits 3-7 are reserved.