





Internet Engineering Task Force (IETF)                           K. Raza
Request for Comments: 7506                           Cisco Systems, Inc.
Updates: 4379                                                   N. Akiya
Category: Standards Track                            Big Switch Networks
ISSN: 2070-1721                                             C. Pignataro
                                                     Cisco Systems, Inc.
                                                              April 2015


                        IPv6 Router Alert Option
       for MPLS Operations, Administration, and Maintenance (OAM)

Abstract

   RFC 4379 defines the MPLS Label Switched Path (LSP) Ping/Traceroute
   mechanism in which the Router Alert Option (RAO) MUST be set in the
   IP header of the MPLS Echo Request messages and may conditionally be
   set in the IP header of the MPLS Echo Reply messages depending on the
   Reply Mode used.  While a generic "Router shall examine packet"
   Option Value is used for the IPv4 RAO, there is no generic RAO value
   defined for IPv6 that can be used.  This document allocates a new,
   generic IPv6 RAO value that can be used by MPLS Operations,
   Administration, and Maintenance (OAM) tools, including the MPLS Echo
   Request and MPLS Echo Reply messages for MPLS in IPv6 environments.
   Consequently, it updates RFC 4379.

   The initial motivation to request an IPv6 RAO value for MPLS OAM
   comes from the MPLS LSP Ping/Traceroute.  However, this value is
   applicable to all MPLS OAM and not limited to MPLS LSP Ping/
   Traceroute.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7506.







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RFC 7506               MPLS OAM IPv6 Router Alert             April 2015


Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specification of Requirements . . . . . . . . . . . . . . . .   3
   3.  IPv6 RAO Value for MPLS OAM . . . . . . . . . . . . . . . . .   3
   4.  Updates to RFC 4379 . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   A commonly deployed MPLS OAM tool is specified in [RFC4379],
   "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures",
   which is used to diagnose MPLS network data planes.  This
   specification, often referred to as "MPLS LSP Ping/Traceroute"
   [RFC4379], requires the use of the Router Alert Option (RAO) in the
   IP header.  For example, Section 4.3 of [RFC4379] states that the IP
   RAO MUST be set in the IP header of an MPLS Echo Request message.
   Similarly, Section 4.5 of [RFC4379] states that the IP RAO MUST be
   set in the IP header of an MPLS Echo Reply message if the Reply Mode
   in the Echo Request is set to "Reply via an IPv4/IPv6 UDP packet with
   Router Alert".

   [RFC2113] defines a generic Option Value 0x0 for IPv4 RAO that is
   used in LSP Ping and LSP Traceroute for MPLS in IPv4 environments.
   This IPv4 RAO value of 0x0 is assigned to "Router shall examine
   packet".  However, currently there is no generic IPV6 RAO value
   defined that can be used in LSP Ping and LSP Traceroute for MPLS in



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RFC 7506               MPLS OAM IPv6 Router Alert             April 2015


   IPv6 environments.  Specifically, [RFC2711] defined the Router Alert
   for a general IPv6 purpose but required the Value field in the RAO to
   indicate a specific reason for using the RAO.  Because there is no
   defined value for MPLS LSP Ping/Traceroute use or for general use, it
   is not possible for MPLS OAM tools to use the IPv6 Router Alert
   mechanism.

   As vendors are starting to implement MPLS on the IPv6 control plane
   (e.g., [LDP-IPV6]), there is a need to define and allocate such an
   Option Value for IPv6 in order to comply with [RFC4379].  This
   document defines a new IPv6 RAO value that can be used by MPLS OAM
   tools, including the MPLS Echo Request and MPLS Echo Reply messages
   for MPLS in IPv6 environments.

   This document closes the gap discussed in the third paragraph of
   Section 3.4.2 in [RFC7439].

2.  Specification of Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  IPv6 RAO Value for MPLS OAM

   This document defines a new Option Value (69) for the IPv6 RAO to
   alert transit routers to examine the packet more closely for MPLS OAM
   purposes.  This Option Value is used by any MPLS OAM application that
   requires their packets to be examined by a transit router.

   In the scope of this document, this Option Value will be used by the
   MPLS Echo Request and MPLS Echo Reply for its IPv6 messages, as is
   required by [RFC4379].

4.  Updates to RFC 4379

   [RFC4379] specifies the use of the RAO in the IP header.  Sections
   4.3 and 4.5 of [RFC4379] are updated as follows:

   For every time in which the "Router Alert IP Option" is used, the
   following text is appended:

      In case of an IPv4 header, the generic IPv4 RAO value 0x0
      [RFC2113] SHOULD be used.  In case of an IPv6 header, the IPv6 RAO
      value (69) allocated through this document for MPLS OAM MUST be
      used.





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5.  IANA Considerations

   This document defines a new value (69) for the IPv6 RAO to alert
   transit routers to examine the packet more closely for MPLS OAM
   purposes.  IANA has assigned a new code point under its "IPv6 Router
   Alert Option Values" registry defined by [RFC2711], updated by
   [RFC5350], and maintained in [IANA-IPv6-RAO].  The new code point is
   as follows:

      Value   Description                       Reference
      -----   -------------------------------   ---------------
         69   MPLS OAM                          RFC 7506

6.  Security Considerations

   This document introduces no new security concerns in addition to what
   have already been captured in [RFC4379] and [RFC6398], the latter of
   which expands the security considerations of [RFC2113] and [RFC2711].

   IPv6 packets containing the MPLS OAM RAO are encapsulated with an
   MPLS header and are not expected to be inspected by every label
   switched hop within an MPLS LSP.  Consequently, this value of the RAO
   will be processed by the appropriate router and is not subject to the
   problem of being ignored, as described in Section 2.2 of [RFC7045].

7.  References

7.1.  Normative References

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

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

   [RFC4379]  Kompella, K. and G. Swallow, "Detecting Multi-Protocol
              Label Switched (MPLS) Data Plane Failures", RFC 4379,
              February 2006, <http://www.rfc-editor.org/info/rfc4379>.

   [RFC5350]  Manner, J. and A. McDonald, "IANA Considerations for the
              IPv4 and IPv6 Router Alert Options", RFC 5350, September
              2008, <http://www.rfc-editor.org/info/rfc5350>.

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



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7.2.  Informative References

   [IANA-IPv6-RAO]
              IANA, "IPv6 Router Alert Option Values",
              <http://www.iana.org/assignments/ipv6-routeralert-values>.

   [LDP-IPV6] Asati, R., Pignataro, C., Raza, K., Manral, V., and R.
              Papneja, "Updates to LDP for IPv6", Work in Progress,
              draft-ietf-mpls-ldp-ipv6-17, February 2015.

   [RFC2113]  Katz, D., "IP Router Alert Option", RFC 2113, February
              1997, <http://www.rfc-editor.org/info/rfc2113>.

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045, December 2013,
              <http://www.rfc-editor.org/info/rfc7045>.

   [RFC7439]  George, W., Ed. and C. Pignataro, Ed., "Gap Analysis for
              Operating IPv6-Only MPLS Networks", RFC 7439, January
              2015, <http://www.rfc-editor.org/info/rfc7439>.

Acknowledgements

   The authors would like to thank George Swallow, Ole Troan, Bob
   Hinden, Faisal Iqbal, Mathew Janelle, and Gregory Mirsky for their
   useful input.

























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RFC 7506               MPLS OAM IPv6 Router Alert             April 2015


Authors' Addresses

   Kamran Raza
   Cisco Systems, Inc.
   2000 Innovation Drive
   Kanata, ON  K2K-3E8
   Canada

   EMail: skraza@cisco.com


   Nobo Akiya
   Big Switch Networks

   EMail: nobo.akiya.dev@gmail.com


   Carlos Pignataro
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   United States

   EMail: cpignata@cisco.com



























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