6man                                                           R. Bonica
Internet-Draft                                          Juniper Networks
Updates: RFC 2711 (if approved)                         30 December 2021
Intended status: Standards Track
Expires: 3 July 2022


              Deprecation Of The IPv6 Router Alert Option
              draft-bonica-6man-deprecate-router-alert-00

Abstract

   This document deprecates the IPv6 Router Alert Option.  Protocols
   that use the Router Alert Option may continue to do so.  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.

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   This Internet-Draft will expire on 3 July 2022.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   3.  Updates To RFC 2711 . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

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:

   *  Accepts a packet.

   *  Determines the packet's next hop.

   *  Forwards the packet to its next hop.



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   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:

   *  The control plane sends FIB updates to the forwarding plane so it
      can maintain a read-only FIB copy.

   *  The control plane sends routing protocol messages through the
      forwarding plane to other nodes.

   *  The forwarding plane sends routing protocol messages received from
      other nodes and addressed to the router to the control plane.

   *  The forwarding plane sends messages that are not addressed to the
      router but include the IPv6 Router Alert Option [RFC2711] to the
      control plane.  The control plane inspects these messages and
      returns them to the forwarding plane so that they can continue on
      to their ultimate destination.

   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.




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

   *  "Network operators SHOULD actively protect themselves against
      externally generated IP Router Alert packets."

   *  "Applications and protocols SHOULD NOT be deployed with a
      dependency on processing of the Router Alert Option (as currently
      specified) across independent administrative domains in the
      Internet."

   *  "Router implementations of the IP Router Alert Option SHOULD offer
      the configuration option to simply ignore the presence of "IP
      Router Alert" in IPv4 and IPv6 packets."

   *  "A router implementation SHOULD forward within the "fast path"
      (subject to all normal policies and forwarding rules) a packet
      carrying the IP Router Alert Option containing a next level
      protocol that is not a protocol of interest to that router."

   NOTE: In RFC 6398, the terms "fast path" and "control 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.  However,
   protocols standardized in the future MUST NOT use the Router Alert
   Option.





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   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.

      +====================+============+==========================+
      | Protocol           | References | Application              |
      +====================+============+==========================+
      | Multicast Listener | [RFC3810]  | IPv6 Multicast           |
      | Discovery Version  |            |                          |
      | 2 (MLDv2)          |            |                          |
      +--------------------+------------+--------------------------+
      +--------------------+------------+--------------------------+
      | Multicast Router   | [RFC4286]  | IPv6 Multicast           |
      | Discovery (MRD)    |            |                          |
      +--------------------+------------+--------------------------+
      +--------------------+------------+--------------------------+
      | MPLS PING          | [RFC8029]  | MPLS OAM                 |
      +--------------------+------------+--------------------------+
      +--------------------+------------+--------------------------+
      | Resource           | [RFC3175]  | Integrated Services      |
      | Reservation        | [RFC5946]  | (INTSERV) [RFC1633] (Not |
      | Protocol (RSVP)    | [RFC6016]  | Traffic engineering or   |
      |                    | [RFC6401]  | MPLS signaling)          |
      +--------------------+------------+--------------------------+
      +--------------------+------------+--------------------------+
      | Next Steps In      | [RFC5979]  | NSIS [RFC4080]           |
      | Signaling (NSIS)   | [RFC5971]  |                          |
      +--------------------+------------+--------------------------+

         Table 1: Protocols That Use The IPv6 Router Alert Option

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 (
   https://www.iana.org/assignments/ipv6-parameters/
   ipv6-parameters.xhtml#ipv6-parameters-2) and add a pointer to this
   document.







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6.  Acknowledgements

   Thanks to Bob Hinden for his review of this document.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2711]  Partridge, C. and A. Jackson, "IPv6 Router Alert Option",
              RFC 2711, DOI 10.17487/RFC2711, October 1999,
              <https://www.rfc-editor.org/info/rfc2711>.

   [RFC6398]  Le Faucheur, F., Ed., "IP Router Alert Considerations and
              Usage", BCP 168, RFC 6398, DOI 10.17487/RFC6398, October
              2011, <https://www.rfc-editor.org/info/rfc6398>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

7.2.  Informative References

   [RFC1633]  Braden, R., Clark, D., and S. Shenker, "Integrated
              Services in the Internet Architecture: an Overview",
              RFC 1633, DOI 10.17487/RFC1633, June 1994,
              <https://www.rfc-editor.org/info/rfc1633>.

   [RFC3175]  Baker, F., Iturralde, C., Le Faucheur, F., and B. Davie,
              "Aggregation of RSVP for IPv4 and IPv6 Reservations",
              RFC 3175, DOI 10.17487/RFC3175, September 2001,
              <https://www.rfc-editor.org/info/rfc3175>.

   [RFC3810]  Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
              Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
              DOI 10.17487/RFC3810, June 2004,
              <https://www.rfc-editor.org/info/rfc3810>.





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   [RFC4080]  Hancock, R., Karagiannis, G., Loughney, J., and S. Van den
              Bosch, "Next Steps in Signaling (NSIS): Framework",
              RFC 4080, DOI 10.17487/RFC4080, June 2005,
              <https://www.rfc-editor.org/info/rfc4080>.

   [RFC4286]  Haberman, B. and J. Martin, "Multicast Router Discovery",
              RFC 4286, DOI 10.17487/RFC4286, December 2005,
              <https://www.rfc-editor.org/info/rfc4286>.

   [RFC5946]  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, October 2010,
              <https://www.rfc-editor.org/info/rfc5946>.

   [RFC5971]  Schulzrinne, H. and R. Hancock, "GIST: General Internet
              Signalling Transport", RFC 5971, DOI 10.17487/RFC5971,
              October 2010, <https://www.rfc-editor.org/info/rfc5971>.

   [RFC5979]  Shen, C., Schulzrinne, H., Lee, S., and J. Bang, "NSIS
              Operation over IP Tunnels", RFC 5979,
              DOI 10.17487/RFC5979, March 2011,
              <https://www.rfc-editor.org/info/rfc5979>.

   [RFC6016]  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, October 2010,
              <https://www.rfc-editor.org/info/rfc6016>.

   [RFC6192]  Dugal, D., Pignataro, C., and R. Dunn, "Protecting the
              Router Control Plane", RFC 6192, DOI 10.17487/RFC6192,
              March 2011, <https://www.rfc-editor.org/info/rfc6192>.

   [RFC6401]  Le Faucheur, F., Polk, J., and K. Carlberg, "RSVP
              Extensions for Admission Priority", RFC 6401,
              DOI 10.17487/RFC6401, October 2011,
              <https://www.rfc-editor.org/info/rfc6401>.

   [RFC8029]  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, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.

Author's Address






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

   Email: rbonica@juniper.net












































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