path: root/doc/rfc/rfc7156.txt

Internet Engineering Task Force (IETF)                           G. Zorn
Request for Comments: 7156                                   Network Zen
Category: Standards Track                                          Q. Wu
ISSN: 2070-1721                                                   Huawei
                                                             J. Korhonen
                                                                Broadcom
                                                              April 2014


        Diameter Support for Proxy Mobile IPv6 Localized Routing

Abstract

   In Proxy Mobile IPv6, packets received from a Mobile Node (MN) by the
   Mobile Access Gateway (MAG) to which it is attached are typically
   tunneled to a Local Mobility Anchor (LMA) for routing.  The term
   "localized routing" refers to a method by which packets are routed
   directly between an MN's MAG and the MAG of its Correspondent Node
   (CN) without involving any LMA.  In a Proxy Mobile IPv6 deployment,
   it may be desirable to control the establishment of localized routing
   sessions between two MAGs in a Proxy Mobile IPv6 domain by requiring
   that the session be authorized.  This document specifies how to
   accomplish this using the Diameter protocol.

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/rfc7156.














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Copyright Notice

   Copyright (c) 2014 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Attribute Value Pair Used in This Document  . . . . . . . . .   4
     4.1.  User-Name AVP . . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  PMIP6-IPv4-Home-Address AVP . . . . . . . . . . . . . . .   5
     4.3.  MIP6-Home-Link-Prefix AVP . . . . . . . . . . . . . . . .   5
     4.4.  MIP6-Feature-Vector AVP . . . . . . . . . . . . . . . . .   5
   5.  Example Signaling Flows for Localized Routing Service
       Authorization . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  10
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11

















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1.  Introduction

   Proxy Mobile IPv6 (PMIPv6) [RFC5213] allows the Mobile Access Gateway
   (MAG) to optimize media delivery by locally routing packets from a
   Mobile Node (MN) to a Correspondent Node (CN) that is locally
   attached to an access link connected to the same Mobile Access
   Gateway, avoiding tunneling them to the Mobile Node's Local Mobility
   Anchor (LMA).  This is referred to as "local routing" in RFC 5213
   [RFC5213].  However, this mechanism is not applicable to the typical
   scenarios in which the MN and CN are connected to different MAGs and
   are registered to the same LMA or different LMAs.  [RFC6279] takes
   those typical scenarios into account and defines the problem
   statement for PMIPv6 localized routing.  Based on the scenarios A11,
   A12, and A21 described in [RFC6279], [RFC6705] specifies the PMIPv6
   localized routing protocol that is used to establish a localized
   routing path between two Mobile Access Gateways in a PMIPv6 domain.

   This document describes Authentication, Authorization, and Accounting
   (AAA) support using Diameter [RFC6733]  for the authorization
   procedure between the PMIPv6 mobility entities (MAG or LMA) and a AAA
   server within a Proxy Mobile IPv6 domain for localized routing in the
   scenarios A11, A12, and A21 described in [RFC6279].

2.  Terminology

   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.  Solution Overview

   This document addresses how to provide authorization information to
   the Mobile Node's MAG or LMA to enable localized routing and resolve
   the destination MN's MAG by means of interaction between the LMA and
   the AAA server.  Figure 1 shows the reference architecture for
   Localized Routing Service Authorization.  This reference architecture
   assumes that

   o  If the MN and CN belong to different LMAs, the MN and CN should
      share the same MAG (i.e., scenario A12 described in [RFC6279]),
      e.g., MN1 and CN2 in Figure 1 are attached to MAG1 and belong to
      LMA1 and LMA2, respectively.  Note that LMA1 and LMA2 in Figure 1
      are in the same provider domain (as described in [RFC6279]).

   o  If the MN and CN are attached to different MAGs, the MN and CN
      should belong to the same LMA (i.e., scenario A21 described in
      [RFC6279]); for example, MN1 and CN3 in Figure 1 are attached to
      MAG1 and MAG3, respectively, but belong to LMA1.



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   o  The MN and CN may belong to the same LMA and may be attached to
      the same MAG (i.e., scenario A11 described in [RFC6279]), e.g.,
      MN1 and CN1 in Figure 1 are both attached to the MAG1 and belong
      to LMA1.

   o  The MAG and LMA support Diameter client functionality.

                                   +---------+
           +---------------------->|  AAA &  |
           |               +------>| Policy  |
           |               |       | Profile |
           |           Diameter    +---------+
           |               |
           |            +--V-+    +----+
           |   +------->|LMA1|    |LMA2|
           |   |        +---++    +----+
           |   |          | |       |
      Diameter |          | +-------+---------
           |   |          |         |        |
           |  PMIP        |         |        \\
           |   |         //        //         \\
           |   |        //        //           \\
           |   |       //        //             \\
           |   |       |         |               |
           |   +---->+---------------+         +----+
           |         |     MAG1      |         |MAG3|
           +-------->+---------------+         +----+
                       :    :      :              :
                    +---+  +---+  +---+         +---+
                    |MN1|  |CN1|  |CN2|         |CN3|
                    +---+  +---+  +---+         +---+

        Figure 1: Localized Routing Service Authorization Reference
                               Architecture

   The interaction of the MAG and LMA with the AAA server according to
   the extension specified in this document is used to authorize the
   localized routing service.

4.  Attribute Value Pair Used in This Document

   This section describes Attribute Value Pairs (AVPs) and AVP values
   defined by this specification or reused from existing specifications
   in a PMIPv6-specific way.







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4.1.  User-Name AVP

   The User-Name AVP (AVP Code 1) is defined in [RFC6733], Section 8.14.
   This AVP is used to carry the Mobile Node identifier (MN-Identifier)
   [RFC5213] in the Diameter AA-Request message [RFC7155] sent to the
   AAA server.  The MN-Identifier is defined in PMIPv6 [RFC5213].

4.2.  PMIP6-IPv4-Home-Address AVP

   The PMIP6-IPv4-Home-Address AVP (AVP Code 505) is defined in
   [RFC5779], Section 5.2.  This AVP is used to carry the Mobile Node's
   IPv4 home address (IPv4-MN-HoA) in the Diameter AA-Request message
   [RFC7155] sent to the AAA server.  The IPv4-MN-HoA is defined in
   [RFC5844].

4.3.  MIP6-Home-Link-Prefix AVP

   The MIP6-Home-Link-Prefix AVP (AVP Code 125) is defined in [RFC5779],
   Section 5.3.  This AVP is used to carry the Mobile Node's home
   network prefix (MN-HNP) in the Diameter AA-Request [RFC7155] sent to
   the AAA server.

4.4.  MIP6-Feature-Vector AVP

   The MIP6-Feature-Vector AVP is defined in [RFC5447] and contains a
   64-bit flags field used to indicate supported capabilities to the AAA
   server.  This document allocates a new capability flag bit according
   to the IANA rules in RFC 5447 [RFC5447].

   INTER_MAG_ROUTING_SUPPORTED (0x0002000000000000)

      When set, this flag indicates support or authorization of Direct
      routing of IP packets between MNs anchored to different MAGs
      without involving any LMA.

   During the network access authentication and authorization procedure
   [RFC5779], this flag is set by the MAG or LMA in the MIP6-Feature-
   Vector AVP included in the request to indicate to the home AAA server
   (HAAA) that inter-MAG direct routing may be provided to the mobile
   node identified by the User-Name AVP.  By setting the
   INTER_MAG_ROUTING_SUPPORTED flag in the response, the HAAA indicates
   to the MAG or LMA that direct routing of IP packets between this
   mobile node and another node anchored to a different MAG is
   authorized.  The MAG and the LMA set also the
   INTER_MAG_ROUTING_SUPPORTED flag of the MIP6-Feature-Vector AVP in
   AA-R sent to the HAAA for requesting authorization of inter-MAG
   direct routing between the mobile nodes identified in the request by
   two distinct instances of the User-Name AVP.  If this bit is set in



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   the returned MIP6-Feature-Vector AVP, the HAAA authorizes direct
   routing of packets between MNs anchored to different MAGs.  When the
   INTER_MAG_ROUTING_SUPPORTED flag is cleared, either in request or
   response, it indicates that the procedures related to authorization
   of localized routing between MNs anchored to different MAGs is not
   supported or not authorized.  MAG and LMA compliant to this
   specification MUST support this policy feature on a per-MN and per-
   subscription basis.

5.  Example Signaling Flows for Localized Routing Service Authorization

   Localized Routing Service Authorization can happen during the network
   access authentication procedure [RFC5779] before localized routing is
   initialized.  In this case, the preauthorized pairs of LMA / prefix
   sets can be downloaded to Proxy Mobile IPv6 entities during the
   procedure from [RFC5779].  Localized routing can be initiated once
   the destination of a received packet matches one or more of the
   prefixes received during the procedure from [RFC5779].

   Figure 2 shows an example scenario in which MAG1 acts as a Diameter
   client, processing the data packet from MN1 to MN2 and requesting
   authorization of localized routing (i.e., MAG-Initiated LR
   authorization).  In this example scenario, MN1 and MN2 are attached
   to the same MAG and anchored to the different LMAs (i.e., scenario
   A12 described in [RFC6279]).  In this case, MAG1 knows that MN2
   belongs to a different LMA (which can be determined by looking up the
   binding cache entries corresponding to MN1 and MN2 and comparing the
   addresses of LMA1 and LMA2).  In order to set up a localized routing
   path with MAG2, MAG1 acts as Diameter client and sends an AA-Request
   message to the AAA server.  The message contains an instance of the
   MIP6-Feature-Vector (MFV) AVP [RFC5447] with the
   LOCAL_MAG_ROUTING_SUPPORTED bit ([RFC5779], Section 5.5) set, two
   instances of the User-Name AVP [RFC6733] containing the identifiers
   of MN1 and MN2.  In addition, the message may contain either:

   - an instance of the MIP6-Home-Link-Prefix AVP [RFC5779] carrying the
     MN1's IPv4 address;

   - an instance of the PMIP6-IPv4-Home-Address AVP [RFC5779] carrying
     the MN1's home network prefix (MN-HNP).

   The AAA server authorizes the localized routing service by checking
   if MN1 and MN2 are allowed to use localized routing.  If so, the AAA
   server responds with a AAA message encapsulating an instance of the
   MIP6-Feature-Vector (MFV) AVP [RFC5447] with the
   LOCAL_MAG_ROUTING_SUPPORTED bit ([RFC5779], Section 5.5) set
   indicating that direct routing of IP packets between MNs anchored to
   the same MAG is authorized.  MAG1 then knows that the localized



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   routing between MN1 and MN2 is allowed.  Then, MAG1 sends the Request
   messages respectively to LMA1 and LMA2.  The request message is the
   Localized Routing Initialization (LRI) message in Figure 2 and
   belongs to the Initial phase of the localized routing.  LMA1 and LMA2
   respond to MAG1 using the Localized Routing Acknowledge message (LRA
   in Figure 2) in accordance with [RFC6705].

   In case of LRA_WAIT_TIME expiration [RFC6705], MAG1 should ask for
   authorization of localized routing again according to the procedure
   described above before the LRI is retransmitted up to a maximum of
   LRI_RETRIES.

      +---+   +---+    +----+    +----+       +---+   +----+
      |MN2|   |MN1|    |MAG1|    |LMA1|       |AAA|   |LMA2|
      +-|-+   +-+-+    +-+--+    +-+--+       +-+-+   +-+--+
        |       |     Anchored     |            |       |
        o-----------------------------------------------o
        |       |     Anchored     |            |       |
        |       o------------------o            |       |
        |     Data[MN1->MN2]       |            |       |
        |       |------->|         |            |       |
        |       |        |  AA-Request(MFV, MN1,MN2)    |
        |       |        |--------------------> |       |
        |       |        |     AA-Answer(MFV)   |       |
        |       |        |<-------------------- |       |
        |       |        |   LRI   |            |       |
        |       |        |-------->|            |       |
        |       |        |         |   LRI      |       |
        |       |        |----------------------------->|
        |       |        |   LRA   |            |       |
        |       |        |<--------|            |       |
        |       |        |         |   LRA      |       |
        |       |        |<-----------------------------|

      Figure 2: MAG-Initiated Localized Routing Authorization in A12

   Figure 3 shows the second example scenario, in which LMA1 acts as a
   Diameter client, processing the data packet from MN2 to MN1 and
   requesting the authorization of localized routing.  In this scenario,
   MN1 and MN2 are attached to a different MAG and anchored to the same
   LMA (i.e., A21 described in [RFC6279]), LMA knows that MN1 and MN2
   belong to the same LMA (which can be determined by looking up the
   binding cache entries corresponding to MN1 and MN2 and comparing the
   addresses of the LMA corresponding to MN1 and LMA corresponding to
   MN2).  In contrast with the signaling flow shown in Figure 2, it is
   LMA1 instead of MAG1 that initiates the setup of the localized
   routing path.




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   The Diameter client in LMA1 sends an AA-Request message to the AAA
   server.  The message contains an instance of the MIP6-Feature-Vector
   (MFV) AVP [RFC5447] with the INTER_MAG_ROUTING_SUPPORTED bit
   (Section 4.5) set indicating direct routing of IP packets between MNs
   anchored to different MAGs is supported and two instances of the
   User-Name AVP [RFC6733] containing identifiers of MN1 and MN2.  The
   AAA server authorizes the localized routing service by checking if
   MN1 and MN2 are allowed to use localized routing.  If so, the AAA
   server responds with an AA-Answer message encapsulating an instance
   of the MIP6-Feature-Vector (MFV) AVP [RFC5447] with the
   INTER_MAG_ROUTING_SUPPORTED bit (Section 4.5) set indicating that
   direct routing of IP packets between MNs anchored to different MAGs
   is authorized.  LMA1 then knows the localized routing is allowed.  In
   a successful case, LMA1 responds to MAG1 in accordance with
   [RFC6705].

   In the case of LRA_WAIT_TIME expiration [RFC6705], LMA1 should ask
   for authorization of localized routing again according to the
   procedure described above before the LRI is retransmitted up to a
   maximum of LRI_RETRIES.

   +---+    +----+  +----+     +---+    +----+   +---+
   |MN1|    |MAG1|  |LMA1|     |AAA|    |MAG2|   |MN2|
   +-+-+    +-+--+  +-+--+     +-+-+    +-+--+   +-+-+
     |        |       |         Anchored  |        |
     |     Anchored   o-------------------+--------o
     o--------+-------o Data[MN2->MN1]    |        |
     |        |       |<-----    |        |        |
     |        |       |AA-Request(MFV,MN1,MN2)     |
     |        |       |--------->|        |        |
     |        |       |AA-Answer(MFV)     |        |
     |        |  LRI  |<---------|        |        |
     |        |<------|        LRI        |        |
     |        |  LRA  |------------------>|        |
     |        |------>|        LRA        |        |
     |        |       |<------------------|        |

      Figure 3: LMA-Initiated Localized Routing Authorization in A21

   Figure 4 shows another example scenario, in which LMA1 acts as a
   Diameter client, processing the data packet from MN2 to MN1 and
   requesting the authorization of localized routing.  In this scenario,
   MN1 and MN2 are attached to the same MAG and anchored to the same LMA
   (i.e., A11 described in [RFC6279]), the LMA knows that MN1 and MN2
   belong to the same LMA (which can be determined by looking up the
   binding cache entries corresponding to MN1 and MN2 and comparing the
   addresses of LMA corresponding to MN1 and LMA corresponding to MN2).




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   The Diameter client in LMA1 sends an AA-Request message to the AAA
   server.  The message contains an instance of the MIP6-Feature-Vector
   AVP [RFC5447] with the LOCAL_MAG_ROUTING_SUPPORTED bit set and two
   instances of the User-Name AVP [RFC6733] containing the identifiers
   MN1 and MN2.  The AAA server authorizes the localized routing service
   by checking if MN1 and MN2 are allowed to use localized routing.  If
   so, the AAA server responds with an AA-Answer message encapsulating
   an instance of the MIP6-Feature-Vector (MFV) AVP [RFC5447] with the
   LOCAL_MAG_ROUTING_SUPPORTED bit ([RFC5779], Section 5.5) set
   indicating that direct routing of IP packets between MNs anchored to
   the same MAG is authorized.  LMA1 then knows the localized routing is
   allowed and responds to MAG1 for localized routing in accordance with
   [RFC6705].

   In the case of LRA_WAIT_TIME expiration [RFC6705], LMA1 should ask
   for authorization of localized routing again according to the
   procedure described above before the LRI is retransmitted up to a
   maximum of LRI_RETRIES.

   +---+  +---+    +----+  +----+     +---+
   |MN2|  |MN1|    |MAG1|  |LMA1|     |AAA|
   +-+-+  +-+-+    +-+--+  +-+--+     +-|-+
     |      |     Anchored   |          |
     o-----------------------o          |
     |      |     Anchored   |          |
     |      o--------+-------o Data[MN2->MN1]
     |      |        |       |<-----    |
     |      |        |       |AA-Request(MFV,MN1,MN2)
     |      |        |       |--------->|
     |      |        |       |AA-Answer(MFV)
     |      |        |  LRI  |<---------|
     |      |        |<------|          |
     |      |        |  LRA  |          |
     |      |        |------>|          |

      Figure 4: LMA-Initiated Localized Routing Authorization in A11

6.  Security Considerations

   The security considerations for the Diameter Network Access Server
   Requirements (NASREQ) [RFC7155] and Diameter Proxy Mobile IPv6
   [RFC5779] applications are also applicable to this document.

   The service authorization solicited by the MAG or the LMA relies upon
   the existing trust relationship between the MAG/LMA and the AAA
   server.





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   An authorized MAG could, in principle, track the movement of any
   participating mobile nodes at the level of the MAG to which they are
   anchored.  If such a MAG were compromised, or under the control of a
   bad actor, then such tracking could represent a privacy breach for
   the set of tracked mobile nodes.  In such a case, the traffic pattern
   from the compromised MAG might be notable, so monitoring for, e.g.,
   excessive queries from MAGs, might be worthwhile.

7.  IANA Considerations

   This specification defines a new value in the "Mobility Capability
   Registry" [RFC5447] for use with the MIP6-Feature-Vector AVP:
   INTER_MAG_ROUTING_SUPPORTED (see Section 4.4).

8.  Contributors

   Paulo Loureiro, Jinwei Xia and Yungui Wang all contributed to early
   versions of this document.

9.  Acknowledgements

   The authors would like to thank Lionel Morand, Marco Liebsch, Carlos
   Jesus Bernardos Cano, Dan Romascanu, Elwyn Davies, Basavaraj Patil,
   Ralph Droms, Stephen Farrel, Robert Sparks, Benoit Claise, and Abhay
   Roy for their valuable comments and suggestions on this document.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

   [RFC5447]  Korhonen, J., Bournelle, J., Tschofenig, H., Perkins, C.,
              and K. Chowdhury, "Diameter Mobile IPv6: Support for
              Network Access Server to Diameter Server Interaction", RFC
              5447, February 2009.

   [RFC5779]  Korhonen, J., Bournelle, J., Chowdhury, K., Muhanna, A.,
              and U. Meyer, "Diameter Proxy Mobile IPv6: Mobile Access
              Gateway and Local Mobility Anchor Interaction with
              Diameter Server", RFC 5779, February 2010.

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.



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   [RFC6705]  Krishnan, S., Koodli, R., Loureiro, P., Wu, Q., and A.
              Dutta, "Localized Routing for Proxy Mobile IPv6", RFC
              6705, September 2012.

   [RFC6733]  Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
              "Diameter Base Protocol", RFC 6733, October 2012.

   [RFC7155]  Zorn, G., Ed., "Diameter Network Access Server
              Application", RFC 7155, April 2014.

10.2.  Informative References

   [RFC6279]  Liebsch, M., Jeong, S., and Q. Wu, "Proxy Mobile IPv6
              (PMIPv6) Localized Routing Problem Statement", RFC 6279,
              June 2011.

Authors' Addresses

   Glen Zorn
   Network Zen
   227/358 Thanon Sanphawut
   Bang Na, Bangkok  10260
   Thailand

   Phone: +66 (0) 87-040-4617
   EMail: glenzorn@gmail.com


   Qin Wu
   Huawei Technologies Co., Ltd.
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Phone: +86-25-56623633
   EMail: bill.wu@huawei.com


   Jouni Korhonen
   Broadcom
   Porkkalankatu 24
   FIN-00180 Helsinki
   Finland

   EMail: jouni.nospam@gmail.com






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