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Versions: (draft-zhou-netext-pd-pmip) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 7148

NETEXT WG                                                        X. Zhou
Internet-Draft                                           ZTE Corporation
Intended status: Standards Track                             J. Korhonen
Expires: November 20, 2013                                Renesas Mobile
                                                             C. Williams
                                                              Consultant
                                                           S. Gundavelli
                                                                   Cisco
                                                           CJ. Bernardos
                                                                    UC3M
                                                            May 19, 2013


            Prefix Delegation Support for Proxy Mobile IPv6
                      draft-ietf-netext-pd-pmip-08

Abstract

   This specification defines extensions to Proxy Mobile IPv6 protocol
   for allowing a mobile router in a Proxy Mobile IPv6 domain to obtain
   delegated IP prefixes for its attached mobile networks.  The mobility
   entities in the network will provide network-based mobility
   management support for those delegated IP prefixes just as how IP
   mobility support is provided for the mobile node's home address.
   Even as the mobile router performs an handoff and changes its network
   point of attachment, mobility support is ensured for all the
   delegated IP prefixes and for all the IP nodes in the mobile network
   that use IP address configuration from those delegated IP prefixes.

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 http://datatracker.ietf.org/drafts/current/.

   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 November 20, 2013.

Copyright Notice




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   Copyright (c) 2013 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.  Convention and Terminology . . . . . . . . . . . . . . . . . .  5
   3.  Solution Overview  . . . . . . . . . . . . . . . . . . . . . .  7
     3.1.  Stated Assumptions . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Deployment Models  . . . . . . . . . . . . . . . . . . . .  7
       3.2.1.  Delegating Router Co-located with Mobile Access
               Gateway  . . . . . . . . . . . . . . . . . . . . . . .  7
       3.2.2.  Delegating Router Co-located with Local Mobility
               Anchor . . . . . . . . . . . . . . . . . . . . . . . .  8
       3.2.3.  Static Configuration of Delegated Mobile Network
               Prefixes . . . . . . . . . . . . . . . . . . . . . . .  9
   4.  Message formats  . . . . . . . . . . . . . . . . . . . . . . . 11
     4.1.  Delegated Mobile Network Prefix Option . . . . . . . . . . 11
     4.2.  Status Codes . . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Operational Details  . . . . . . . . . . . . . . . . . . . . . 13
     5.1.  MAG Considerations . . . . . . . . . . . . . . . . . . . . 13
       5.1.1.  Extension to Binding Update List Entry Data
               Structure  . . . . . . . . . . . . . . . . . . . . . . 13
       5.1.2.  Signaling Considerations . . . . . . . . . . . . . . . 13
       5.1.3.  Packet Forwarding  . . . . . . . . . . . . . . . . . . 17
     5.2.  LMA Considerations . . . . . . . . . . . . . . . . . . . . 18
       5.2.1.  Extensions to Binding Cache Entry Data Structure . . . 18
       5.2.2.  Signaling Considerations . . . . . . . . . . . . . . . 18
       5.2.3.  Packet Forwarding  . . . . . . . . . . . . . . . . . . 20
     5.3.  Security Policy Database (SPD) Example Entries . . . . . . 20
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 23
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 24
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 25
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 25
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26



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1.  Introduction

   Proxy Mobile IPv6 [RFC5213] enables network-based mobility management
   support for an IP host without requiring its participation in any IP
   mobility signaling.  The mobility elements in the network allow an IP
   host to obtain an IPv4 address and/or a set of IPv6 addresses and be
   able to obtain IP mobility support for those IP address(es) within
   the Proxy Mobile IPv6 domain.  In this context, the mobility
   management support that is enabled is for an individual IP host,
   which is the mobile node.  The IPv4 home address, or the IPv6 home
   network prefixes are logically bound to the link shared between the
   mobile access gateway and the mobile node and only the mobile node
   can use those IP address(es) by configuring them on the interface
   attached to that link.  Currently, there is no mobility support for
   the mobile networks attached to a mobile router in a Proxy Mobile
   IPv6 domain.

   This specification defines extensions to the Proxy Mobile IPv6
   protocol for allowing mobility support to the mobile networks
   attached to a mobile router.  The mobile router can request the
   mobility entities in the Proxy Mobile IPv6 domain for one or more
   delegated IP prefixes using DHCP Prefix Delegation extensions
   [RFC3633], or through other mechanisms outside the scope of this
   document.  The mobility entities in the network will provide network-
   based mobility management support for those delegated prefixes just
   as how mobility is supported for an home address.  The delegated
   prefixes are hosted in the mobile network attached to the mobile
   router.  IP mobility is ensured for all the IP nodes in the mobile
   network, even as the mobile router performs an handoff by changing
   its point of network attachment within the Proxy Mobile IPv6 domain.
   The local mobility anchor in the Proxy Mobile IPv6 domain will not
   track the individual IP sessions for all the IP nodes in the mobile
   network, it only tracks a single mobile router session that is
   hosting the mobile network and associates the delegated IP prefixes
   with that session.
















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                                      _----_
                       +-------+    _(      )_
                       |       |---( Internet )
                       |  LMA  |    (_      _)
                       |       |      '----'
                       +-------+
                           |
                      === === ===
                   ==    Proxy    ==
                ==    Mobile IPv6    ==
                   ==    Domain   ==
                      === === ===
                ___________|___________
               |                       |
           +-------+               +-------+
           |  MAG  |               |  MAG  |
           +-------+               +-------+
               .
               .
        - - - - - - - -
       |   +------+    |
       |   |  MR  |    |
       |   +------+    |
       |       |       |
       |    -------    |
       |    |     |    |
       |   LFN   LFN   |
        - - - - - - - -

            Figure 1: Mobile Router in Proxy Mobile IPv6 Domain

   Within the context of this document, the definition of a mobile
   router extends that of a mobile node definition from [RFC5213], by
   adding routing capability for routing IP packets between its egress
   interface (interface used for attachment to the mobile access
   gateway) and any of its ingress interfaces (interface used for
   attachment to the mobile network).  The network of nodes part of the
   mobile network are referred to as locally fixed nodes (LFN) and they
   all move with the mobile router as a single cluster.  Figure 1
   illustrates a mobile router in a Proxy Mobile IPv6 domain.

   The rest of the document identifies the protocol extensions and the
   operational details of the local mobility anchor and mobile access
   gateway for supporting this specification.







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2.  Convention and 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].

   All the mobility related terms used in this document are to be
   interpreted as defined in Proxy Mobile IPv6 specifications [RFC5213]
   and [RFC5844].  All the DHCP related terms are to be interpreted as
   defined in DHCPv6-PD for NEMO [RFC6276], DHCPv6-PD [RFC3633] and
   Subnet Allocation Option for DHCPv4 [RFC6656].  This document also
   provides a context-specific explanation to the following terms used
   in this document.

   Mobile Router (MR)

      The term mobile router is used to refer to an IP router whose
      mobility is managed by the network while being attached to a Proxy
      Mobile IPv6 domain.  The mobile router is a mobile node as defined
      in [RFC5213], but with additional capabilities for supporting an
      attached mobile network.  The mobility entities in the Proxy
      Mobile IPv6 domain provide mobility for the IPv4/IPv6 address(es)
      assigned to the mobile node's egress link and also mobility
      support to the network prefixes hosted in the network attached to
      the mobile router.

   Mobile Network

      It is an IP network attached to a mobile router.  There can be
      many IP nodes in this IP network.  The mobile router is a gateway
      for these IP nodes for reaching other IP networks or the Internet.
      The mobile router and the attached IP networks move as a single
      cluster.

   Delegated Mobile Network Prefix (DMNP)

      The Delegated Mobile Network Prefix is an IPv4/IPv6 prefix
      delegated to a mobile router and is hosted in the mobile network.
      The IP nodes in the mobile network will be able to obtain IP
      address configuration from the delegated mobile network prefix and
      will have IP mobility support for that address configuration.  The
      DMNP is topologically anchored on the local mobility anchor and
      the mobility elements in the Proxy Mobile IPv6 domain provide IP
      mobility support for the prefix, by forwarding the mobile network
      traffic to the mobile router.

   Locally Fixed Node (LFN)




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      A Locally Fixed Node is an IP node in the mobile network.  As the
      mobile router performs an handoff and changes its network point of
      attachement, the locally fixed node moves along with the mobile
      router.















































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3.  Solution Overview

   This section provides an overview of the operation of this
   specification, as well as lists the stated assumptions.  This
   specification references three different deployment scenarios and
   explains the protocol operation.

3.1.  Stated Assumptions

   o  The mobile router is a mobile node as defined in [RFC5213], but
      with additional capabilities for routing IP packets between its
      egress interface (interface used for attachment to the mobile
      access gateway) and any of its ingress interfaces (interface used
      for attachment to the mobile network).

   o  The specification assumes that a mobile router is an IPv4 and/or
      IPv6 router without any capability for mobility management.

   o  The mobile router can obtain the delegated IP prefix(es) for its
      attached mobile networks using DHCPv6, or using mechanisms outside
      of this document (Example: Static Configuration, or access
      technology specific mechanisms).  This document makes no
      assumption on the support of any one specific approach.  However,
      it explains the protocol operation using DHCPv6-based prefix
      delegation as specified in [RFC3633] and with the use of Prefix
      Exclude Option for DHCPv6-PD as described in [RFC6603].  It
      defines an interworking between the mobility entities and the
      DHCPv6 functional elements in a non-normative way.

   o  The mobile router obtains the IP address configuration for its
      egress roaming interface as specified in [RFC5213] and [RFC5844].
      The mobile router along with its mobile networks will be able to
      perform handoff and change its point of attachment in the network
      and will be able to retain IP mobility support.

3.2.  Deployment Models

   This section explains the protocol operation for supporting prefix
   delegation support in Proxy Mobile IPv6 for the following three
   deployment_models.  The high-level message call flows between the
   mobile router, mobile access gateway and the local mobility anchor
   are presented.

3.2.1.  Delegating Router Co-located with Mobile Access Gateway

   o  The delegating router (DR) function, as specified in [RFC3633], is
      co-located with the mobile access gateway.




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   o  The requesting router (RR) function, as specified in [RFC3633], is
      enabled on the mobile router.


      +-----+            +-----+                    +-----+
      | MR  |            | MAG |                    | LMA |
      |(RR) |            | (DR)|                    |     |
      +-----+            +-----+                    +-----+
   1)    |-- MN Attach -----|                          |
         |                  |--------- PBU ----------->|
         |                  |                          |
         |                  |<-------- PBA ------------|
         |                  |                          |
         |                  |o========================o|
   2)    |                  |      PMIPv6 tunnel       |
         |                  |o========================o|
   3)    |-- Solicit for -->|                          |
         | delegated prefix |                          |
   4)    |                  |----------PBU------------>|
         |                  |                          |
   5)    |                  |<---------PBA (DMNP)------|
         |                  |                          |
         -                  -<---+                     |
   6)    |<- Advertise -----|    |                     |
         |                  |    |                     |
   7)    |-- Request ------>| Optional                 |
         |                  |    |                     |
         -                  -<---+                     |
   8)    |<-- Reply (DMNP) -|                          |
         |                  |                          |
         |                  |                          |

     Figure 2: Delegating Router Co-located with Mobile Access Gateway

3.2.2.  Delegating Router Co-located with Local Mobility Anchor

   o  The delegating router (DR) function, as specified in [RFC3633], is
      co-located with the local mobility anchor.

   o  A DHCPv6 Relay Agent (DRA) function, as specified in [RFC3315], is
      co-located on the mobile access gateway.

   o  The requesting router (RR) function, as specified in [RFC3633], is
      enabled on the mobile router.







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      +-----+            +-----+                    +-----+
      | MR  |            | MAG |                    | LMA |
      |(RR) |            |(DRA)|                    |(DR) |
      +-----+            +-----+                    +-----+
   1)    |-- MN Attach -----|                          |
         |                  |--------- PBU ----------->|
         |                  |                          |
         |                  |<-------- PBA ------------|
         |                  |                          |
         |                  |o========================o|
   2)    |                  |      PMIPv6 tunnel       |
         |                  |o========================o|
   3)    |-- Solicit for -->|                          |
         | delegated prefix |                          |
   4)    |                  |--- Solicit ------------->|
         -                  -                          - <---+
   5)    |                  |<-- Advertise ------------|     |
         |                  |                          |     |
   6)    |<- Advertise -----|                          |     |
         |                  |                          |  Optional
   7)    |-- Request ------>|                          |     |
         |                  |                          |     |
   8)    |                  |--- Request ------------->|     |
         -                  -                          - <---+
   9)    |                  |<-- Reply (DMNP) ---------|
         |                  |                          |
   10)   |                  |----------PBU (DNMP)----->|
         |                  |                          |
   11)   |                  |<---------PBA (DMNP)------|
         |                  |                          |
   12)   |<-- Reply (DMNP) -|                          |
         |                  |                          |

     Figure 3: Delegating Router Co-located with Local Mobility Anchor

3.2.3.  Static Configuration of Delegated Mobile Network Prefixes

   o  The delegated mobile network prefixes of the mobile router are
      statically configured in the mobile node's policy profile
      [RFC5213].

   o  The delegated mobile network prefixes are statically configured in
      the mobile network attached to the mobile router.  The mobile
      router is the default-router for the mobile networks.

   o  The mobile access gateway obtains statically configured mobile
      network prefixes from the policy profile and registers them with
      the local mobility anchor using the extensions specified in this



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      document.  There is no explicit trigger from the mobile router
      from registering, or de-registering those prefixes.  As long as
      there is a mobility session for the mobile router's home address,
      the local mobility anchor enables mobility support for the mobile
      network prefixes.


      +-----+            +-----+                    +-----+
      | MR  |            | MAG |                    | LMA |
      |     |            |     |                    |     |
      +-----+            +-----+                    +-----+
   1)    |-- MN Attach -----|                          |
   2)    |                  - (Policy Profile)         |
         |                  |                          |
   3)    |                  |--------- PBU (DMNP) ---->|
         |                  |                          |
   4)    |                  |<-------- PBA (DMNP) -----|
         |                  |                          |
         |                  |o========================o|
   5)    |                  |      PMIPv6 tunnel       |
         |                  |o========================o|
         |                  |                          |

     Figure 4: Delegating Router Co-located with Local Mobility Anchor



























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4.  Message formats

   This section defines extensions to Proxy Mobile IPv6 [RFC5213]
   protocol messages.

4.1.  Delegated Mobile Network Prefix Option

   A new mobility header option, Delegated Mobile Network Prefix option
   is defined for use with Proxy Binding Update and Proxy Binding
   Acknowledgment messages exchanged between a local mobility anchor and
   a mobile access gateway.  This option is used for exchanging the
   mobile router's IPv4/IPv6 delegated mobile network prefix.  There can
   be multiple instances of the Delegated Mobile Network Prefix option
   present in a message.

   The Delegated Mobile Network Prefix option has an alignment
   requirement of 8n+2.  Its format is as follows:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |   Length      |V|  Reserved   | Prefix Length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   .                                                               .
   +           IPv4 or IPv6 Delegated Mobile Network Prefix        +
   |                         (DMNP)                                |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Type

      <IANA-1>: To be assigned by IANA.

   Length

      8-bit unsigned integer indicating the length of the option in
      octets, excluding the type and length fields.

   IPv4 Prefix (V)

      If the IPv4 Prefix (V) flag is set to a value of (1), then it
      indicates that the prefix that is included in the DMNP field is an
      IPv4 prefix.  If the IPv4 Prefix (V) flag is set to a value of



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      (0), then it indicates that the prefix that is included in the
      DMNP field is an IPv6 prefix.

   Reserved

      This field is unused for now.  The value MUST be initialized to 0
      by the sender and MUST be ignored by the receiver.

   Prefix Length

      8-bit unsigned integer indicating the prefix length of the prefix
      contained in the option.

   Delegated Mobile Network Prefix

      Contains a mobile router's 4-byte IPv4 or a 16-byte IPv6 Delegated
      Mobile Network Prefix.

4.2.  Status Codes

   This document defines the following new status code values for use in
   the Proxy Binding Acknowledgement message.  These values have been
   allocated from the same number space as defined in Section 6.1.8 of
   [RFC6275].

   NOT_AUTHORIZED_FOR_DELEGATED_MNP: <IANA-2>

      Not Authorized for delegated mobile network prefix

   REQUESTED_DMNP_IN_USE: <IANA-3>

      Requested delegated mobile network prefix is in use



















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5.  Operational Details

5.1.  MAG Considerations

5.1.1.  Extension to Binding Update List Entry Data Structure

   In order to support this specification, the conceptual Binding Update
   List Entry (BULE) data structure [RFC5213] needs to be extended to
   include delegated mobile network prefix (DMNP) list.  Each entry in
   the list is used for storing an IPv4/IPv6 mobile network prefix
   delegated to the mobile router.

5.1.2.  Signaling Considerations

   o  The mobile node's policy profile defined in [RFC5213] is extended
      to include a parameter which indicates Delegated Prefix support.
      During the mobile router's initial attachment procedure, the
      mobile access gateway obtains the mobile router's policy profile,
      as per the procedures defined in [RFC5213].  If the policy profile
      indicates that the mobile router is authorized for Delegated
      Prefix support, then the following considerations apply.

   o  For requesting the local mobility anchor to allocate delegated
      mobile network prefix(es) for the mobile router, the mobile access
      gateway MUST include one or more Delegated Mobile Network Prefix
      (DMNP) options in the Proxy Binding Update message.

      *  There MUST be exactly one instance of the Delegated Mobile
         Network Prefix option with ALL_ZERO value and with the (V) flag
         set to a value of (0).  This serves as a request to the local
         mobility anchor to allocate a set of delegated IPv6 mobile
         network prefixes.

      *  There MUST be exactly one instance of the Delegated Mobile
         Network Prefix option with ALL_ZERO value and with the (V) flag
         set to a value of (1).  This serves as a request to the local
         mobility anchor to allocate a set of delegated IPv4 mobile
         network prefixes.

      *  There MUST be exactly one instance of the Delegated Mobile
         Network Prefix option with NON_ZERO prefix value for each of
         the mobile network prefixes that the mobile access gateway is
         requesting the local mobility anchor to allocate.  The prefix
         value in the option is the prefix that is either statically
         configured for that mobile router, or obtained via DHCP prefix
         delegation.  This serves as a request to the local mobility
         anchor to allocate the requested IPv4/IPv6 prefix.




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   o  If the received Proxy Binding Acknowledgement message has the
      status field value set to NOT_AUTHORIZED_FOR_DELEGATED_MNP (Not
      Authorized for delegated mobile network prefix), the mobile access
      gateway MUST NOT enable mobility support for any of the prefixes
      in the mobile network and prefix delegation support has to be
      disabled.

   o  If the received Proxy Binding Acknowledgement message has the
      status field value set to REQUESTED_DMNP_IN_USE (Requested
      delegated mobile network prefix is in use), the mobile access
      gateway MUST NOT enable mobility support for the requested
      prefixes.  The mobile access gateway MAY choose to send Proxy
      Binding Acknowledgement message requesting the local mobility
      anchor to perform the prefix assignment.

   o  If the received Proxy Binding Acknowledgement message has the
      status field value set to 0 (Proxy Binding Update accepted), the
      mobile access gateway has to apply the following considerations.

      *  The delegated mobile network prefix (DMNP) list in the mobile
         router's Binding Update List entry has to be updated with the
         allocated prefix(es).  However, if the received message was in
         response to a de-registration request with a lifetime value of
         (0), then the delegated mobile network prefix list has to be
         removed along with the Binding Update List entry.

      *  The mobile access gateway has to set up a policy-based route
         for forwarding the IP packets received from the mobile network
         (with the source IP address from any of the delegated IPv4/IPv6
         mobile network prefixes) through the bidirectional tunnel set
         up for that mobile router.  However, if the received message
         was in response to a de-registration request with a lifetime
         value of (0), then the created forwarding state has to be
         removed.

5.1.2.1.  DHCP - MAG Interactions

   This section describes the interactions between the DHCP and PMIPv6
   logical entities running on the mobile access gateway.  This section
   is applicable only for deployments that use DHCPv6-based prefix
   delegation.  As described next, these interactions vary slightly
   depending on the considered deployment model at the mobile access
   gateway (described in Section 3.2).

   The mobile router, acting as a "Requesting Router" as described in
   [RFC3633], sends a SOLICIT message including one or more IA_PD
   option(s) to the Delegating Router/DHCPv6 Relay Agent collocated on
   the mobile access gateway.  This message provides the needed trigger



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   for the mobile access gateway for requesting the local mobility
   anchor to enable delegated mobile network prefix support for that
   mobility session.

   o  Delegating router co-located with mobile access gateway

      *  The mobile access gateway applies the considerations in
         Section 5.1.2 for requesting the local mobility anchor to
         enable delegated prefix support.  For example, if the mobile
         router is soliciting an IPv4 prefix, the mobile access gateway
         includes in the Proxy Binding Update signaling a Delegated
         Mobile Network Prefix option with ALL_ZERO value and with the
         (V) flag set to a value of (1).

      *  The mobile access gateway, upon successfully completing the
         Proxy Binding Update signaling with the local mobility anchor
         (following the considerations described in Section 5.1.2), adds
         the delegated mobile network prefixes to the binding update
         list.  Then, the mobile access gateway provides the obtained
         prefixes to the DHCPv6 Delegating Router for prefix assignment.
         The way in which the mobile access gateway provides the DHCPv6
         Delegating Router with this information is beyond the scope of
         this document.

         +  In case the Proxy Binding Update signaling with the local
            mobility anchor is not completed successfully, for example
            because the local mobility anchor is not authorized for
            delegated mobile network prefix or the requested prefix is
            in use, the DHCPv6 Delegating Router will send a Reply
            message to the Requesting Router containing the IA_PD with
            the lifetimes of the prefixes in the IA_PD set to zero.

      *  The standard DHCPv6 considerations will be applied with respect
         to the interactions between the Delegating Router and the
         Requesting Router.  The Delegating Router is provided with the
         delegated prefix(es), which can then be then advertised in the
         mobile network, and therefore used by the locally fixed nodes
         to auto configure IP addresses allowing to gain access to the
         Internet.

      *  Any time, the Requesting Router releases the delegated
         prefixes, the Delegating Router removes the assigned prefixes.
         To do so, the mobile access gateway will send an Updated Proxy
         Binding Update following the considerations described in
         Section 5.1.2 for deregistering those prefixes.  The way in
         which the DHCPv6 Delegating Router triggers the mobile access
         gateway in order to deregister the prefixes is beyond the scope
         of this document.



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      *  In case the mobile router performs a handover and attaches to a
         different mobile access gateway, the following cases are
         possible:

         +  The new mobile access gateway does not support the
            delegation of mobile network prefixes described in this
            specification.  In this case, forwarding of the previously
            delegated mobile network prefixes is no longer performed.

         +  The new mobile access gateway supports the delegation of
            mobile network prefixes described in this specification.  In
            this case, the Delegating Router, upon the reception of the
            SOLICIT message, will learn the delegated mobile network
            prefixes from the Proxy Binding Update signaling performed
            with the local mobility anchor.

   o  Delegating router co-located with local mobility anchor

      *  A DHCPv6 Relay Agent function running on the mobile access
         gateway will forward the DHCP messages to the local mobility
         anchor which has the co-located Delegating Router function.
         The Requesting Router and the Delegating Router complete the
         DHCP messages related to prefix delegation.

      *  During the DHCPv6 exchange, the standard DHCPv6 considerations
         apply with respect to the interactions between the Delegating
         Router, DHCPv6 Relay Agent and the Requesting Router.

      *  The mobile access gateway learns from the co-located DHCPv6
         Relay Agent the prefixes allocated by the Delegating Router.
         The way in which the mobile access gateway learns obtains this
         information from the DHCPv6 Relay Agent is beyond the scope of
         this document.

      *  The mobile access gateway will apply the considerations in
         Section 5.1.2 for requesting the local mobility anchor to
         enable delegated prefix support.  The mobile access gateway
         will include exactly one instance of the Delegated Mobile
         Network Prefix option with NON_ZERO prefix value for each of
         the mobile network prefixes that the mobile access gateway is
         requesting the local mobility anchor to allocate.  The prefix
         value(s) in the option will be the prefix(es) obtained via DHCP
         prefix delegation.

      *  The mobile access gateway, upon successfully completing the
         Proxy Binding Update signaling with the local mobility anchor,
         will provide the obtained prefixes to the DHCPv6 Relay Agent
         for prefix assignment.  The Delegating Router is provided with



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         the delegated prefix(es) completing the standard DHCPv6
         signaling.  These prefixes can then be then advertised in the
         mobile network, and therefore used by the locally fixed nodes
         to auto configure IP addresses allowing to gain access to the
         Internet.

         +  In case the Proxy Binding Update signalling with the local
            mobility anchor is not completed successfully, for example
            because the local mobility anchor is not authorized for
            delegated mobile network prefix, the requeted prefix is in
            use, or the delegated prefix(es) do not match the ones
            allocated by DHCP prefix delegation, the DHCPv6 Relay Agent
            MAY send a Reply message to the Requesting Router containing
            the IA_PD with the lifetimes of the prefixes in the IA_PD
            set to zero.

      *  In case the mobile router performs a handover and attaches to a
         different mobile access gateway, the following cases are
         possible:

         +  The new mobile access gateway does not support the
            delegation of mobile network prefixes described in this
            specification.  In this case, forwarding of the previously
            delegated mobile network prefixes is no longer performed.

         +  The new mobile access gateway supports the delegation of
            mobile network prefixes described in this specification.  In
            this case, the DHCPv6 Relay Agent, upon the reception of the
            SOLICIT message, will learn the delegated mobile network
            prefixes from the Proxy Binding Update signaling performed
            with the local mobility anchor.

5.1.3.  Packet Forwarding

   o  On receiving an IP packet from a mobile router, the mobile access
      gateway before tunneling the packet to the local mobility anchor
      MUST ensure that there is an established binding for the mobile
      router and the source IP address of the packet is a prefix
      delegated to that mobile router.  If the source address of the
      received IP packet is not part of the delegated mobile network
      prefix, then the mobile access gateway MUST NOT tunnel the packet
      to the local mobility anchor.

   o  On receiving an IP packet from the bi-directional tunnel
      established with the local mobility anchor, the mobile access
      gateway MUST first decapsulate the packet (removing the outer
      header) and then use the destination address of the (inner) packet
      to forward it on the interface through which the mobile router is



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      reachable.

   o  The above forwarding considerations are not applicable to the IP
      traffic sent/received to/from the mobile router's home address
      (IPv4 HOA/HNP).  For the mobile router's home address traffic,
      forwarding considerations from [RFC5213] and [RFC5844] continue to
      apply.

5.2.  LMA Considerations

5.2.1.  Extensions to Binding Cache Entry Data Structure

   In order to support this specification, the conceptual Binding Cache
   Entry (BCE) data structure [RFC5213] needs to be extended to include
   the delegated mobile network prefix (DMNP) list.  Each entry in the
   list represents a delegated mobile network prefix.

5.2.2.  Signaling Considerations

   o  If the Proxy Binding Update message does not include any Delegated
      Mobile Network Prefix option(s) (Section 4.1), then the local
      mobility anchor MUST NOT enable Delegated Prefix support for the
      mobility session, and the Proxy Binding Acknowledgment message
      that is sent in response MUST NOT contain any Delegated Mobile
      Network Prefix option(s).

   o  If the Proxy Binding Update message includes one or more Delegated
      Mobile Network Prefix options, but either the local mobility
      anchor is not configured to support Delegated Prefix support, then
      the local mobility anchor will ignore the option(s) and process
      the rest of the option as specified in [RFC5213].  This would have
      no effect on the operation of the rest of the protocol.  The Proxy
      Binding Acknowledgement message that is sent in response will not
      include any Delegated Mobile Network Prefix option(s).

   o  If the Proxy Binding Update message has the Delegated Mobile
      Network Prefix option(s) and if the local mobility anchor is
      configured for Delegated Prefix support, then the local mobility
      anchor MUST enable Delegated Mobile Network Prefix option for that
      mobility session.  The Proxy Binding Acknowledgement message that
      is sent in response MUST include the Delegated Mobile Network
      Prefix option(s).  The following considerations apply.

      *  If there is at least one instance of the Delegated Mobile
         Network Prefix option with a ALL_ZERO [RFC5213] prefix value,
         then this serves as a request for the local mobility anchor to
         perform the assignment of one or more delegated mobile network
         prefixes.



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         +  A Delegated Mobile Network option with ALL_ZERO value and
            with the (V) flag set to a value of (0), is a request for
            the local mobility anchor to allocate one or more IPv6
            prefixes.

         +  A Delegated Mobile Network option with ALL_ZERO value and
            with the (V) flag set to a value of (1), is a request for
            the local mobility anchor to allocate one or more IPv4
            prefixes.

         +  Inclusion of multiple instances of Delegated Mobile Network
            options with ALL_ZERO value, one with the (V) flag set to a
            value of (1), and another instance with the (V) flag set to
            a value of (0) is a request to allocate both IPv4 and IPv6
            prefixes.

      *  If there are no instances of the Delegated Mobile Network
         Prefix option present in the request with ALL_ZERO value, but
         has a specific prefix value, then this serves as a request for
         the local mobility anchor to perform the allocation of the
         requested prefix(es).

         +  If any one of the requested prefixes are assigned to some
            other mobility node, or not from an authorized pool that the
            local mobility can allocate for that mobility session, then
            the Proxy Binding Update MUST be rejected by sending a Proxy
            Binding Acknowledgement message with Status field set to
            REQUESTED_DMNP_IN_USE (Requested delegated mobile network
            prefix is in use).

   o  Upon accepting the Proxy Binding Update, the local mobility anchor
      MUST send a Proxy Binding Acknowledgement message with the Status
      field set to 0 (Proxy Binding Update accepted).

      *  The message MUST include one instance of the Delegated Mobile
         Network Prefix option for each of the allocated IPv4/IPv6
         delegated mobile network prefixes.

      *  The delegated mobile network prefix (DMNP) list in the mobile
         router's Binding Cache entry has to be updated with the
         allocated prefix(es).  However, if the request is a de-
         registration request with a lifetime value of (0), the
         delegated mobile network prefix list has to be removed along
         with the Binding Cache entry.

      *  A route (or a platform-specific equivalent function that sets
         up the forwarding) for each of the allocated prefixes over the
         tunnel has to be added.  However, if the request is a de-



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         registration request, with a lifetime value of (0), all the
         IPv4/IPv6 delegated prefix routes created for that session have
         to be removed.

5.2.3.  Packet Forwarding

   o  The local mobility anchor MUST advertise a connected route into
      the Routing Infrastructure for the IP prefixes delegated to all of
      the mobile routers that it is serving.  This step essentially
      enables the local mobility anchor to be a routing anchor for those
      IP prefixes and be able to intercept IP packets sent to those
      mobile networks.

   o  On receiving a packet from a correspondent node with the
      destination address matching any of the mobile router's delegated
      mobile network prefixes, the local mobility anchor MUST forward
      the packet through the bi-directional tunnel set up with the
      mobile access gateway where the mobile router is attached.

   o  On receiving an IP packet from the bi-directional tunnel
      established with the mobile access gateway, the local mobility
      anchor MUST first decapsulate the packet (removing the outer
      header) and then use the destination address of the (inner) packet
      for forwarding decision.  The local mobility anchor MUST ensure
      that there is an established binding for the mobile router and the
      source IP address of the packet is a prefix delegated to a mobile
      router reachable over that bi-directional tunnel.

   o  The above forwarding considerations are not applicable to the IP
      traffic sent/received to/from the mobile router's home address
      (IPv4 HOA/HNP).  For the mobile router's home address traffic,
      forwarding considerations from [RFC5213] and [RFC5844] continue to
      apply.

5.3.  Security Policy Database (SPD) Example Entries

   The use of DHCPv6, as described in this document, requires message
   integrity protection and source authentication.  The IPsec security
   mechanism used by Proxy Mobile IPv6 [RFC5213] for securing the
   signaling messages between the mobile access gateway and the local
   mobility anchor can be used for securing the DHCP signaling between
   the mobile access gateway and the local mobility anchor.

   The Security Policy Database (SPD) and Security Association Database
   (SAD) entries necessary to protect the DHCP signaling is specified
   below.  The format of these entries is based on [RFC4877]
   conventions.  The SPD and SAD entries are only example
   configurations.  A particular implementation of mobile access gateway



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   and local mobility anchor implementation can configure different SPD
   and SAD entries as long as they provide the required security for
   protecting DHCP signaling messages.

   For the examples described in this document, a mobile access gateway
   with address "mag_address_1", and a local mobility anchor with
   address "lma_address_1" are assumed.

      mobile access gateway SPD-S:
        - IF local_address = mag_address_1 &
             remote_address = lma_address_1 & proto = UDP &
             local_port = any & remote_port = DHCP
          Then use SA1 (OUT) and SA2 (IN)

      mobile access gateway SAD:
        - SA1(OUT, spi_a, lma_address_1, ESP, TRANSPORT):
              local_address = mag_address_1 &
              remote_address = lma_address_1 &
              proto = UDP & remote_port = DHCP
        - SA2(IN, spi_b, mag_address_1, ESP, TRANSPORT):
              local_address = lma_address_1 &
              remote_address = mag_address_1 &
              proto = UDP & local_port = DHCP

      local mobility anchor SPD-S:
        - IF local_address = lma_address_1 &
             remote_address = mag_address_1 & proto = UDP &
             local_port = DHCP & remote_port = any
          Then use SA2 (OUT) and SA1 (IN)

      local mobility anchor SAD:
        - SA2(OUT, spi_b, mag_address_1, ESP, TRANSPORT):
              local_address = lma_address_1 &
              remote_address = mag_address_1 &
              proto = UDP & local_port = DHCP
        - SA1(IN, spi_a, lma_address_1, ESP, TRANSPORT):
              local_address = mag_address_1 &
              remote_address = lma_address_1 &
              proto = UDP & remote_port = DHCP












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6.  Security Considerations

   The Delegated Mobile Network Prefix Option defined in this
   specification is for use in Proxy Binding Update and Proxy Binding
   Acknowledgement messages.  This option is carried like any other
   mobility header option as specified in [RFC5213].  Therefore, it
   inherits from [RFC5213] its security guidelines and does not require
   any additional security considerations.

   The use of DHCPv6 in this specification is as defined in DHCPv6 base
   specification [RFC3315] and DHCPv6 Prefix Delegation specifications
   [RFC3633].  The security considerations specified in those
   specifications apply to this specification.

   If IPsec is used, the IPsec security association that is used for
   protecting the Proxy Binding Update and Proxy Binding
   Acknowledgement, also needs to be used for protecting the DHCPv6
   signaling between the mobile access gateway and the local mobility
   anchor.  Considerations specified in Section 5.3 identify the
   extensions to security policy entries [RFC4301]































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7.  IANA Considerations

   This document requires the following IANA actions.

   o  Action-1: This specification defines a new Mobility Header option,
      Delegated Mobile Network Prefix option.  This mobility option is
      described in Section 4.1.  The type value <IANA-1> for this
      message needs to be allocated from the Mobility Header Types
      registry at http://www.iana.org/assignments/mobility-parameters.
      RFC Editor: Please replace <IANA-1> in Section 4.1 with the
      assigned value, and update this section accordingly.

   o  Action-2: This document also defines two new status code values
      for use in the Proxy Binding Acknowledgement message, as described
      in Section 4.2.  These status codes are,
      NOT_AUTHORIZED_FOR_DELEGATED_MNP (Not Authorized for delegated
      mobile network prefix) with a status code value of <IANA-2>, and
      REQUESTED_DMNP_IN_USE (Requested delegated mobile network prefix
      is in use) with a status code value of <IANA-3>.  These values
      have to be assigned from the same number space as allocated for
      other status codes [RFC6275] and update this section accordingly.






























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8.  Acknowledgments

   The authors would like to Acknowledge Ryuji Wakikawa, Alexandru
   Petrescu, Behcet Sarikaya, Seil Jeon and Basavaraj Patil for all the
   discussions and reviews of this draft.

   The work of Carlos J. Bernardos has also been partially supported by
   the European Community's Seventh Framework Programme (FP7-ICT-2009-5)
   under grant agreement n. 258053 (MEDIEVAL project) and by the
   Ministry of Science and Innovation of Spain under the QUARTET project
   (TIN2009-13992-C02-01).








































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9.  References

9.1.  Normative References

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

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4877]  Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
              IKEv2 and the Revised IPsec Architecture", RFC 4877,
              April 2007.

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

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

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [RFC6276]  Droms, R., Thubert, P., Dupont, F., Haddad, W., and C.
              Bernardos, "DHCPv6 Prefix Delegation for Network Mobility
              (NEMO)", RFC 6276, July 2011.

   [RFC6603]  Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan,
              "Prefix Exclude Option for DHCPv6-based Prefix
              Delegation", RFC 6603, May 2012.

9.2.  Informative References

   [RFC6656]  Johnson, R., Kinnear, K., and M. Stapp, "Description of
              Cisco Systems' Subnet Allocation Option for DHCPv4",
              RFC 6656, July 2012.







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Authors' Addresses

   Xingyue Zhou
   ZTE Corporation
   No.50 Software Avenue, Yuhuatai District
   Nanjing
   China

   Phone: +86-25-8801-4634
   Email: zhou.xingyue@zte.com.cn


   Jouni Korhonen
   Renesas Mobile
   Porkkalankatu 24
   Helsinki  FIN-00180
   Finland

   Email: jouni.nospam@gmail.com


   Carl Williams
   Consultant
   San Jose, CA
   USA

   Email: carlw@mcsr-labs.org


   Sri Gundavelli
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Email: sgundave@cisco.com


   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30
   Leganes, Madrid  28911
   Spain

   Phone: +34 91624 6236
   Email: cjbc@it.uc3m.es
   URI:   http://www.it.uc3m.es/cjbc/




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