Internet-Draft Stub Router RA Flag March 2024
Hui Expires 20 September 2024 [Page]
Internet Engineering Task Force
Intended Status:
Standards Track
J. Hui
Google LLC

Stub Router Flag in ICMPv6 Router Advertisement Messages


This document defines a new flag, the Stub Router flag, in the Router Advertisement message that can be used to distinguish configuration information sent by stub routers from information sent by infrastructure routers. This flag is used only by stub 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

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This Internet-Draft will expire on 20 September 2024.

1. Introduction

A stub router is an autonomously-configuring router that provides IP connectivity between one or more stub networks and one or more infrastructure networks. A common stub router example is a device that attaches a 6LoWPAN-based network to a home network, automatically providing IPv6 forwarding between the two networks without explicit operator configuration. Stub routers are described in [I-D.ietf-snac-simple]. This document defines a new RA flag, the "stub router" flag, which stub routers use to identify RAs sent by other stub 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. Stub Router Flag

The "Stub Router" flag is router advertisement flag bit TBD.

The stub router flag is to be used by stub routers. The use of this flag is documented in [I-D.ietf-snac-simple]. Devices that do not implement [I-D.ietf-snac-simple] MUST NOT set the stub router flag, and MUST silently ignore the stub router flag. 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.

4. IANA Considerations

IANA is requested to allocate a flag from the "IPv6 ND Router Advertisement flags" registry of [RFC5175], as specified below:

Table 1
RA Option Bit Description Reference
TBD S - Stub Router Flag This Document

5. Security Considerations

This protocol shares the security issues of NDP that are documented in the "Security Considerations" section of [RFC4861].

6. Normative References

Lemon, T. and J. Hui, "Automatically Connecting Stub Networks to Unmanaged Infrastructure", Work in Progress, Internet-Draft, draft-ietf-snac-simple-04, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, , <>.
Haberman, B., Ed. and R. Hinden, "IPv6 Router Advertisement Flags Option", RFC 5175, DOI 10.17487/RFC5175, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.

Author's Address

Jonathan Hui
Google LLC
1600 Amphitheatre Parkway
Mountain View, California 940432
United States of America