Internet Engineering Task Force J. Hui Internet-Draft Google LLC Intended status: Standards Track 4 December 2024 Expires: 7 June 2025 SNAC Router Flag in ICMPv6 Router Advertisement Messages draft-ietf-6man-snac-router-ra-flag-03 Abstract This document defines a new flag, the SNAC Router flag, in the Router Advertisement message that can be used to distinguish configuration information sent by SNAC routers from information sent by infrastructure routers. This flag is used only by SNAC routers and is ignored by all other devices. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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Hui Expires 7 June 2025 [Page 1] Internet-Draft SNAC Router RA Flag December 2024 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. SNAC Router Flag . . . . . . . . . . . . . . . . . . . . . . 2 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 3 6. Normative References . . . . . . . . . . . . . . . . . . . . 3 7. Informative References . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction A Stub Network Auto-Configuring (SNAC) router is an autonomously configuring router that provides IP connectivity between one or more stub networks and one or more infrastructure networks. A common SNAC router example is a device that attaches a 6LoWPAN-based network [RFC4919] to a home network, automatically providing IPv6 forwarding between the two networks without explicit operator configuration. SNAC routers are described in [I-D.ietf-snac-simple]. This document defines a new IPv6 ND Router Advertisement (RA) flag, the "SNAC router" flag, which SNAC routers use to identify RAs sent by other SNAC routers. 2. Terminology 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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. SNAC Router Flag The "SNAC Router" flag is bit TBD in the RA Flags Extension Option [RFC5175]. The SNAC router flag is to be used by SNAC routers. SNAC routers and the use of this flag are specified in [I-D.ietf-snac-simple]. As defined by Section 4.2 of [RFC4861], devices that do not operate as SNAC routers will not set the SNAC router flag, and routers that do not understand the SNAC router flag will silently ignore it. This means that the presence or absence of the flag should not change the behavior of such devices in any way (other than that it is of course permissible to log and cache the value of the flag as part of normal router advertisement processing, where applicable). Hui Expires 7 June 2025 [Page 2] Internet-Draft SNAC Router RA Flag December 2024 4. IANA Considerations IANA is requested to allocate a flag from the "Internet Control Message Protocol version 6 (ICMPv6) Parameters", "IPv6 ND Router Advertisement flags" registry [IANA-RA-FLAGS] as specified below: +---------------+----------------------+---------------+ | RA Option Bit | Description | Reference | +---------------+----------------------+---------------+ | TBD | S - SNAC Router Flag | This Document | +---------------+----------------------+---------------+ Table 1 5. Security Considerations How SNAC routers process RAs is dependent on the SNAC router flag value, as specified in [I-D.ietf-snac-simple]. The security considerations for SNAC routers processing the SNAC router flag are documented in [I-D.ietf-snac-simple]. The security considerations of IPv6 ND are documented in the "Security Considerations" section of [RFC4861]. The addition of the SNAC router flag does not change these considerations. In environments that implement RA-Guard [RFC7113] in a way that filters RAs sent by SNAC routers, devices on the infrastructure network will never receive an RA with the SNAC router flag set. 6. Normative References [I-D.ietf-snac-simple] Lemon, T. and J. Hui, "Automatically Connecting Stub Networks to Unmanaged Infrastructure", Work in Progress, Internet-Draft, draft-ietf-snac-simple-06, 4 November 2024, . [IANA-RA-FLAGS] IANA, "IPv6 ND Router Advertisement flags", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Hui Expires 7 June 2025 [Page 3] Internet-Draft SNAC Router RA Flag December 2024 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007, . [RFC5175] Haberman, B., Ed. and R. Hinden, "IPv6 Router Advertisement Flags Option", RFC 5175, DOI 10.17487/RFC5175, March 2008, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7. Informative References [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals", RFC 4919, DOI 10.17487/RFC4919, August 2007, . [RFC7113] Gont, F., "Implementation Advice for IPv6 Router Advertisement Guard (RA-Guard)", RFC 7113, DOI 10.17487/RFC7113, February 2014, . Author's Address Jonathan Hui Google LLC 1600 Amphitheatre Parkway Mountain View, California 940432 United States of America Email: jonhui@google.com Hui Expires 7 June 2025 [Page 4]