Internet-Draft Deprecate IPv6 Router Alert February 2024
Bonica Expires 22 August 2024 [Page]
RFC 2711 (if approved)
Intended Status:
Standards Track
R. Bonica
Juniper Networks

Deprecation Of The IPv6 Router Alert Option


This document deprecates the IPv6 Router Alert Option. Protocols that use the Router Alert Option may continue to do so, even in future versions. However, protocols standardized in the future must not use the Router Alert Option.

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

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 22 August 2024.

Table of Contents

1. Introduction

Figure 1 models an Internet router. The router has a forwarding plane and a control plane.

|                                                  |
|                  CONTROL PLANE                   |
|               (OSPF, ISIS, BGP)                  |
|                                                  |
|                 (FIB Read-Write)                 |
      |                   / \
      | FIB updates and    |  Messages addressed
      | routing protocol   |  to the router and
      | messages to        |  messages that contain
      | other nodes        |  the Router Alert Option
     \ /                   |
|                                                  |
|                FORWARDING PLANE                  |
|                    (IPv6)                        |
|                                                  |
|                (FIB Read-Only)                   |
Figure 1: An Internet Router

IPv6 [RFC8200] operates on the forwarding plane. It:

IPv6 determines a packet's next hop by searching the Forwarding Information Base (FIB) for an entry that best matches the packet's destination address. Therefore, IPv6 requires read-only access to the FIB.

Routing protocols (e.g., OSPF, IS-IS, BGP) operate on a router's control plane. They create and maintain the FIB by exchanging routing protocol messages with other nodes. Therefore, the control plane requires read-write access to the FIB.

The forwarding and control planes communicate with one another as follows:

Many routers maintain separation between forwarding and control plane hardware. The forwarding plain is implemented on high-performance Application Specific Integrated Circuits (ASIC) and Network Processors (NP), while the control plane is implemented on general-purpose processors. Therefore, the forwarding plane can process many more packets per second than the control plane. Given this difference in packet-handling capabilities, a router's control plane is more susceptible to a Denial-of-Service (DoS) attack than the router's forwarding plane.

[RFC6192] demonstrates how a network operator can deploy Access Control Lists (ACL) that protect the control plane from DoS attack. These ACLs are effective and efficient when they select packets based upon information that can be found in a fixed position in the packet header. However, they become less effective and less efficient when they must parse an IPv6 Hop-by-hop Options extension header, searching for the Router Alert Option. Therefore, many network operators drop or severely rate limit packets that contain the IPv6 Hop-by-hop Options extension header.

[RFC6398] identifies security considerations associated with the Router Alert Option. It provides the following recommendations:

NOTE: In RFC 6398, the terms "fast path" and "forwarding plane components" are used synonymously.

Network operators can address all of the security considerations raised in RFC 6398 by configuring their routers to ignore the Router Alert Option. However, such configuration may not be possible if protocol designers continue to design protocols that use the Router Alert Option. Alternatively, network operators will be required to deploy the operationally complex and computationally expensive ACLs described in RFC 6192. Therefore, this document deprecates the IPv6 Router Alert Option.

2. Requirements Language

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. Updates To RFC 2711

This document deprecates the IPv6 Router Alert Option. Protocols that use the Router Alert Option MAY continue to do so, even in future versions. However, protocols standardized in the future MUST NOT use the Router Alert Option.

Table 1 contains a list of protocols that use the IPv6 Router Alert Option. There are no known IPv6 implementations of MPLS PING. Neither INTSERV nor NSIS are widely deployed. All NSIS protocols are EXPERIMENTAL. Pragmatic Generic Multicast (PGM) is EXPERIMENTAL and there are no known IPv6 implementations.

Table 1: Protocols That Use The IPv6 Router Alert Option
Protocol References Application
Multicast Listener Discovery Version 2 (MLDv2) [RFC3810] IPv6 Multicast
Multicast Router Discovery (MRD) [RFC4286] IPv6 Multicast
Pragmatic General Multicast (PGM) [RFC3208] IPv6 Multicast
Resource Reservation Protocol (RSVP) [RFC3175] [RFC5946] [RFC6016] [RFC6401] Integrated Services (INTSERV) [RFC1633] (Not Traffic engineering or MPLS signaling)
Next Steps In Signaling (NSIS) [RFC5979] [RFC5971] NSIS [RFC4080]

4. Security Considerations

This document extends the security considerations provided in RFC 2711, RFC 6192 and RFC 6398.

5. IANA Considerations

IANA is requested to mark the Router Alert Option as Deprecated in the Destination Options and Hop-by-hop Options Registry ( and add a pointer to this document.

6. Acknowledgements

Thanks to Brian Carpenter, Toerless Eckert, Adrian Farrel, and Bob Hinden for their reviews of this document.

7. References

7.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Partridge, C. and A. Jackson, "IPv6 Router Alert Option", RFC 2711, DOI 10.17487/RFC2711, , <>.
Le Faucheur, F., Ed., "IP Router Alert Considerations and Usage", BCP 168, RFC 6398, DOI 10.17487/RFC6398, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, , <>.

7.2. Informative References

Braden, R., Clark, D., and S. Shenker, "Integrated Services in the Internet Architecture: an Overview", RFC 1633, DOI 10.17487/RFC1633, , <>.
Baker, F., Iturralde, C., Le Faucheur, F., and B. Davie, "Aggregation of RSVP for IPv4 and IPv6 Reservations", RFC 3175, DOI 10.17487/RFC3175, , <>.
Speakman, T., Crowcroft, J., Gemmell, J., Farinacci, D., Lin, S., Leshchiner, D., Luby, M., Montgomery, T., Rizzo, L., Tweedly, A., Bhaskar, N., Edmonstone, R., Sumanasekera, R., and L. Vicisano, "PGM Reliable Transport Protocol Specification", RFC 3208, DOI 10.17487/RFC3208, , <>.
Vida, R., Ed. and L. Costa, Ed., "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, DOI 10.17487/RFC3810, , <>.
Hancock, R., Karagiannis, G., Loughney, J., and S. Van den Bosch, "Next Steps in Signaling (NSIS): Framework", RFC 4080, DOI 10.17487/RFC4080, , <>.
Haberman, B. and J. Martin, "Multicast Router Discovery", RFC 4286, DOI 10.17487/RFC4286, , <>.
Le Faucheur, F., Manner, J., Narayanan, A., Guillou, A., and H. Malik, "Resource Reservation Protocol (RSVP) Extensions for Path-Triggered RSVP Receiver Proxy", RFC 5946, DOI 10.17487/RFC5946, , <>.
Schulzrinne, H. and R. Hancock, "GIST: General Internet Signalling Transport", RFC 5971, DOI 10.17487/RFC5971, , <>.
Shen, C., Schulzrinne, H., Lee, S., and J. Bang, "NSIS Operation over IP Tunnels", RFC 5979, DOI 10.17487/RFC5979, , <>.
Davie, B., Le Faucheur, F., and A. Narayanan, "Support for the Resource Reservation Protocol (RSVP) in Layer 3 VPNs", RFC 6016, DOI 10.17487/RFC6016, , <>.
Dugal, D., Pignataro, C., and R. Dunn, "Protecting the Router Control Plane", RFC 6192, DOI 10.17487/RFC6192, , <>.
Le Faucheur, F., Polk, J., and K. Carlberg, "RSVP Extensions for Admission Priority", RFC 6401, DOI 10.17487/RFC6401, , <>.
Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert Option for MPLS Operations, Administration, and Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, , <>.
Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., Aldrin, S., and M. Chen, "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures", RFC 8029, DOI 10.17487/RFC8029, , <>.

Author's Address

Ron Bonica
Juniper Networks
2251 Corporate Park Drive
Herndon, Virginia 20171
United States of America