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rfc:rfc6757

Internet Engineering Task Force (IETF) S. Gundavelli, Ed. Request for Comments: 6757 Cisco Category: Standards Track J. Korhonen, Ed. ISSN: 2070-1721 Nokia Siemens Networks

                                                            M. Grayson
                                                              K. Leung
                                                         R. Pazhyannur
                                                                 Cisco
                                                          October 2012
    Access Network Identifier (ANI) Option for Proxy Mobile IPv6

Abstract

 The local mobility anchor in a Proxy Mobile IPv6 (PMIPv6) domain is
 able to provide access-network- and access-operator-specific handling
 or policing of the mobile node traffic using information about the
 access network to which the mobile node is attached.  This
 specification defines a mechanism and a related mobility option for
 carrying the access network identifier and the access operator
 identification information from the mobile access gateway to the
 local mobility anchor over Proxy Mobile IPv6.

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/rfc6757.

Copyright Notice

 Copyright (c) 2012 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

Gundavelli, et al. Standards Track [Page 1] RFC 6757 Access Network Identifier Option October 2012

 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. Conventions and Terminology .....................................5
    2.1. Conventions ................................................5
    2.2. Terminology ................................................5
 3. Access Network Identifier Option ................................5
    3.1. Format of the Access Network Identifier Sub-Option .........6
         3.1.1. Network-Identifier Sub-Option .......................7
         3.1.2. Geo-Location Sub-Option .............................8
         3.1.3. Operator-Identifier Sub-Option ......................9
 4. Protocol Considerations ........................................10
    4.1. Mobile Access Gateway Considerations ......................10
    4.2. Local Mobility Anchor Considerations ......................13
 5. IANA Considerations ............................................14
 6. Protocol Configuration Variables ...............................15
 7. Security Considerations ........................................16
 8. Acknowledgements ...............................................17
 9. References .....................................................17
    9.1. Normative References ......................................17
    9.2. Informative References ....................................18

Gundavelli, et al. Standards Track [Page 2] RFC 6757 Access Network Identifier Option October 2012

1. Introduction

 Proxy Mobile IPv6 [RFC5213] can be used for supporting network-based
 mobility management in various types of network deployments.  Network
 architectures such as service provider Wi-Fi access aggregation or
 Wireless Local Area Network (WLAN) integrated with mobile packet core
 are examples where Proxy Mobile IPv6 is a component of the overall
 architecture.  Some of these architectures require the ability of the
 local mobility anchor (LMA) [RFC5213] to provide differentiated
 services and policing of traffic to the mobile nodes based on the
 access network to which they are attached.  Policy systems in
 mobility architectures such as the Policy and Charging Control (PCC)
 Framework [TS23203] and the Access Network Discovery and Selection
 Function (ANDSF) [TS23402] in Third Generation Partnership Project
 (3GPP) systems allow configuration of policy rules with conditions
 based on the access network information.  For example, the service
 treatment for the mobile node's traffic may be different when it is
 attached to an access network owned by the home operator than when
 owned by a roaming partner.  The service treatment can also be
 different based on the configured Service Set Identifiers (SSIDs) in
 the case of access networks based on IEEE 802.11.  Other examples of
 location services include the operator's ability to display a
 location-specific web page or apply tariff based on the location.
 The Proxy Mobile IPv6 specification [RFC5213] requires the Access
 Technology Type (ATT) option to be carried from the mobile access
 gateway (MAG) to the local mobility anchor.  This is a mandatory
 option.  However, the Access Technology Type alone is not necessarily
 sufficient for a suitable policy to be applied at the local mobility
 anchor.  Therefore, there is a need for additional access-network-
 related information to be available at the local mobility anchor.
 Learning the identity of the access network operator may not be
 possible for a local mobility anchor without the support of an
 additional policy framework that is able to provide required
 information out of band to the local mobility anchor.  Such a policy
 framework may not be required for all Proxy Mobile IPv6 deployments;
 hence, an alternative approach for optionally carrying such
 information is required to ensure that additional information related
 to the access network is available.
 This document defines a new mobility option, the Access Network
 Identifier (ANI) option, and its sub-options for Proxy Mobile IPv6,
 which can be used by the mobile access gateway to signal the access
 network information to the local mobility anchor.  The specific
 details on how the local mobility anchor uses the information
 contained in the Access Network Identifier option are out of scope
 for this document.  This information is intended for use between
 infrastructure nodes providing mobile management service and is not

Gundavelli, et al. Standards Track [Page 3] RFC 6757 Access Network Identifier Option October 2012

 exposed to outside entities, which ensures the location of the
 network to which the mobile node is attached, or any other access-
 network-specific information, is not revealed to other mobile nodes
 within the PMIPv6 domain or to other nodes outside the PMIPv6 domain.
 However, the location and access information MAY be exposed to
 specific parties outside the PMIPv6 domain based on an agreement
 approved by the subscriber; otherwise, this information MUST NOT be
 exposed in the absence of such agreements.  If the location
 information is to be exposed outside the PMIPv6 domain, then that
 MUST be done using a Presence Information Data Format Location Object
 (PIDF-LO) [RFC5139] carrying the usage rules to which the subscriber
 has agreed.  This mobility option is optional and is not mandatory
 for the Proxy Mobile IPv6 protocol.  However, the Access Technology
 Type option continues to be a mandatory option and always needs to be
 carried in the Proxy Mobile IPv6 signaling messages.
     SSID: IETF-1
     Geo-Location: 37o49'11"N 122o28'43"W
     Operator-Identifier: provider1.example.com
     +--+
     |AP|-------.                        {Access-Specific Policies)
     +--+       |             _-----_             |
              +-----+       _(       )_        +-----+
              | MAG |-=====(   PMIPv6  )======-| LMA |-
              +-----+       (_ Tunnel_)        +-----+
     +--+       |             '-----'
     |AP|-------'
     +--+
     SSID: IETF-2
     Geo-Location: 59o19'40.21"N  18o 3'18.36"E
     Operator-Identifier: provider2.example.com
               Figure 1: Access Networks Attached to MAG
 Figure 1 illustrates an example Proxy Mobile IPv6 deployment where
 the mobile access gateway delivers the information elements related
 to the access network to the local mobility anchor over Proxy Mobile
 IPv6 signaling messages.  In this example, the additional information
 could comprise the SSID of the used IEEE 802.11 network, the geo-
 location of the network to which the mobile node is attached, and the
 identities of the operators running the IEEE 802.11 access network
 infrastructure.

Gundavelli, et al. Standards Track [Page 4] RFC 6757 Access Network Identifier Option October 2012

2. Conventions and Terminology

2.1. Conventions

 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 RFC 2119 [RFC2119].

2.2. Terminology

 All the mobility-related terms used in this document are to be
 interpreted as defined in the Proxy Mobile IPv6 specifications
 [RFC5213] and [RFC5844].  Additionally, this document uses the
 following abbreviations:
 Service Set Identifier
    Service Set Identifier (SSID) identifies the name of the IEEE
    802.11 network.  SSID differentiates one network from the other.
 Operator-Identifier
    The Operator-Identifier is the Structure of Management Information
    (SMI) Network Management Private Enterprise Code of the IANA-
    maintained "Private Enterprise Numbers" registry [SMI].  It
    identifies the operator running the network attached to a specific
    interface of the mobile access gateway.

3. Access Network Identifier Option

 The Access Network Identifier option is a mobility header option used
 to exchange information related to the access network between a local
 mobility anchor and a mobile access gateway.  The option can be
 included in both Proxy Binding Update (PBU) and Proxy Binding
 Acknowledgement (PBA) messages, and there MUST NOT be more than a
 single instance of this mobility option in a mobility message.  The
 Access Network Identifier mobility option MUST contain one or more
 Access Network Identifier sub-options.  The Access Network Identifier
 sub-option is described in Section 3.1.

Gundavelli, et al. Standards Track [Page 5] RFC 6757 Access Network Identifier Option October 2012

 The alignment requirement for this option is 4n [RFC2460].
  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      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                ...      ANI Sub-option(s) ...                   ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Figure 2: Access Network Identifier Option
 Type:  MUST be set to the value of 52, indicating that it is a
    Network-Identifier option.
 Length:  8-bit unsigned integer indicating the length in octets of
    the option, excluding the Type and Length fields.

3.1. Format of the Access Network Identifier Sub-Option

 The Access Network Identifier sub-options are used for carrying
 information elements related to the access network to which the
 mobile node is attached.  These sub-options can be included in the
 Access Network Identifier option defined in Section 3.  The format of
 this sub-option 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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |    ANI Type   | ANI Length    |         Option Data           ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Figure 3: Access Network Identifier Sub-Option
 ANI Type:  8-bit unsigned integer indicating the type of the Access
    Network Identifier sub-option.  This specification defines the
    following types:
    0 -  Reserved
    1 -  Network-Identifier sub-option
    2 -  Geo-Location sub-option
    3 -  Operator-Identifier sub-option

Gundavelli, et al. Standards Track [Page 6] RFC 6757 Access Network Identifier Option October 2012

 ANI Length:  8-bit unsigned integer indicating the number of octets
    needed to encode the Option Data, excluding the ANI Type and ANI
    Length fields of the sub-option.

3.1.1. Network-Identifier Sub-Option

 The Network-Identifier is a mobility sub-option carried in the Access
 Network Identifier option defined in Section 3.  This sub-option
 carries the name of the access network (e.g., an SSID in the case of
 an IEEE 802.11 Access Network or a Public Land-based Mobile Network
 (PLMN) Identifier [TS23003] in the case of 3GPP access) to which the
 mobile node is attached.  There MUST be no more than a single
 instance of this specific sub-option in any Access Network Identifier
 option.  The format of this option is defined below.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | ANI Type=1    |  ANI Length   |E|   Reserved  | Net-Name Len  |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                     Network Name (e.g., SSID or PLMNID)       ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | AP-Name Len   |        Access-Point Name                      ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                Figure 4: Network-Identifier Sub-Option
 ANI Type:  MUST be set to the value of (1), indicating that it is a
    Network-Identifier sub-option
 ANI Length:  Total length of this sub-option in octets, excluding the
    ANI Type and ANI Length fields.  The value can be in the range of
    5 to 32 octets.
 E: 1-bit flag indicating whether the Network Name is encoded in
    UTF-8.  If this flag is set to one (1), then the Network Name is
    encoded using UTF-8 [RFC3629].  If the flag is set to zero (0),
    this indicates that the encoding is undefined and is determined by
    out-of-band mechanisms.  Implementations SHOULD use UTF-8
    encoding.
 Reserved:  MUST be set to zero when sending and ignored when
    received.
 Net-Name Length:  8-bit field for representing the length of the
    Network Name in octets.  This field MUST NOT be set to zero.

Gundavelli, et al. Standards Track [Page 7] RFC 6757 Access Network Identifier Option October 2012

 Network Name:  The name of the access network to which the mobile
    node is attached.  The type of the Network Name is dependent on
    the access technology to which the mobile node is attached.  If it
    is 802.11 access, the Network Name MUST be the SSID of the
    network.  If the access network is 3GPP access, the Network Name
    is the PLMN Identifier of the network.  If the access network is
    3GPP2 access, the Network Name is the Access Network Identifier
    [ANI].
    When encoding the PLMN Identifier, both the Mobile Network Code
    (MNC) [TS23003] and Mobile Country Code (MCC) [TS23003] MUST be 3
    digits.  If the MNC in use only has 2 digits, then it MUST be
    preceded with a '0'.  Encoding MUST be UTF-8.
 AP-Name Len:  8-bit field for representing the length of the Access-
    Point Name in octets.  If the Access-Point Name is not included,
    then this length MUST be set to a value of zero.
 Access-Point Name:  The name of the access point (physical device
    name) to which the mobile node is attached.  This is the
    identifier that uniquely identifies the access point.  While
    Network Name (e.g., SSID) identifies the operator's access
    network, Access-Point Name identifies a specific network device in
    the network to which the mobile node is attached.  In some
    deployments, the Access-Point Name can be set to the Media Access
    Control (MAC) address of the device or some unique identifier that
    can be used by the policy systems in the operator network to
    unambiguously identify the device.  The string is carried in UTF-8
    representation.

3.1.2. Geo-Location Sub-Option

 The Geo-Location is a mobility sub-option carried in the Access
 Network Identifier option defined in Section 3.  This sub-option
 carries the geo-location of the network to which the mobile node is
 attached, as known to the mobile access gateway.  There MUST be no
 more than a single instance of this specific sub-option in any Access
 Network Identifier option.  The format of this option is defined
 below and encodes the coordinates of an ellipsoid point.  The format
 is based on the coordinate reference system specified in the World
 Geodetic System 1984 [WGS84].

Gundavelli, et al. Standards Track [Page 8] RFC 6757 Access Network Identifier Option October 2012

  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  ANI Type=2   | ANI Length=6  |       Latitude Degrees
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |              Longitude Degrees                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 Figure 5: Geo-Location ANI Sub-Option
 ANI Type:  MUST be set to the value of (2), indicating that it is the
    Geo-Location sub-option
 ANI Length:  Total length of this sub-option in octets, excluding the
    ANI Type and ANI Length fields.  It MUST be set to a value of (6).
 Latitude Degrees:  A 24-bit latitude degree value encoded as a two's
    complement, fixed point number with 9 whole bits.  Positive
    degrees correspond to the Northern Hemisphere and negative degrees
    correspond to the Southern Hemisphere.  The value ranges from -90
    to +90 degrees.
 Longitude Degrees:  A 24-bit longitude degree value encoded as a
    two's complement, fixed point number with 9 whole bits.  The value
    ranges from -180 to +180 degrees.

3.1.3. Operator-Identifier Sub-Option

 The Operator-Identifier is a mobility sub-option carried in the
 Access Network Identifier option defined in Section 3.  This sub-
 option carries the Operator-Identifier of the access network to which
 the mobile node is attached.  There MUST be no more than a single
 instance of this specific sub-option in any Access Network Identifier
 option.  The format of this option is defined below.
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | ANI Type=3    |    ANI Length   |   Op-ID Type  |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                          Operator-Identifier                    ~
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               Figure 6: Operator-Identifier Sub-Option

Gundavelli, et al. Standards Track [Page 9] RFC 6757 Access Network Identifier Option October 2012

 ANI Type:  It MUST be set to the value of (3), indicating that it is
    the Operator-Identifier sub-option
 ANI Length:  Total length of this sub-option in octets, excluding the
    ANI Type and ANI Length fields.
 Operator-Identifier (Op-ID) Type:  8-bit unsigned integer indicating
    the type of the Operator-Identifier.  Currently, the following
    types are defined:
    0 -  Reserved.
    1 -  Operator-Identifier as a variable-length Private Enterprise
         Number (PEN) [SMI] encoded in a network-byte order.  The
         maximum PEN value depends on the ANI Length and is calculated
         using the formula: maximum PEN = 2^((ANI_length-1)*8)-1.  For
         example, the ANI Length of 4 allows for encoding PENs from 0
         to 2^24-1, i.e., from 0 to 16777215, and uses 3 octets of
         Operator-Identifier space.
    2 -  Realm of the operator.  Realm names are required to be unique
         and are piggybacked on the administration of the DNS
         namespace.  Realms meet the syntactic requirements of the
         "Preferred Name Syntax" defined in Section 2.3.1 of
         [RFC1035].  They are encoded as US-ASCII. 3GPP specifications
         also define realm names that can be used to convey PLMN
         Identifiers [TS23003].
 Operator-Identifier:  Up to 253 octets of the Operator-Identifier.
    The encoding of the identifier depends on the used Operator-
    Identifier Type.  For Operator-Identifiers defined in this
    specification, the Operator-Identifier MUST NOT be empty.

4. Protocol Considerations

 The following considerations apply to the local mobility anchor and
 the mobile access gateway.

4.1. Mobile Access Gateway Considerations

 o  The conceptual Binding Update List entry data structure maintained
    by the mobile access gateway, described in Section 6.1 of
    [RFC5213], MUST be extended to store the access-network-related
    information elements associated with the current session.
    Specifically, the following parameters MUST be defined:

Gundavelli, et al. Standards Track [Page 10] RFC 6757 Access Network Identifier Option October 2012

    Network-Identifier
    Operator-Identifier
    Geo-Location
 o  If the mobile access gateway is configured to support the Access
    Network Information option, it SHOULD include this option with the
    specific sub-options in all Proxy Binding Update messages
    (including Proxy Binding Updates for lifetime extension and for
    deregistration) that it sends to the local mobility anchor.  The
    Access Network Information option MUST be constructed as specified
    in Section 3.  It SHOULD include the ANI sub-option(s) that the
    mobile access gateway is configured to carry in the Proxy Mobile
    IPv6 messages.
 o  The access network information elements, such as Network-
    Identifier, Geo-Location, and Operator-Identifier, typically are
    statically configured on the mobile access gateway on a per-
    interface basis (for example, access point (AP-1) is attached
    through interface-1, and the SSID is X, Geo-Location is Y).  In
    some deployments, this information can also be dynamically
    obtained, such as through DHCP Option (82), which is the DHCP
    Relay Agent Information option [RFC3046].  When the mobile node
    sends a DHCP Request, the access points typically add the SSID
    information to the Option 82 of the DHCP request, and when the
    mobile access gateway receives this request, it can parse the
    Option 82 of the DHCP request and obtain the SSID name.  The
    mobility access gateway can also obtain this information from the
    DHCPv6 GeoLoc Option [RFC6225].  The specific details on how the
    mobile access gateway obtains these information elements are
    access technology and deployment specific and are outside the
    scope of this document.  It is possible those information elements
    are configured on the MAG on a per-interface basis or dynamically
    obtained through some out-of-band means, such as based on the
    Control and Provisioning of Wireless Access Points (CAPWAP)
    protocol.
 o  If the protocol configuration variable
    EnableANISubOptNetworkIdentifier (Section 6) is set to a value of
    (1), the mobile access gateway SHOULD include the Network-
    Identifier sub-option in the Access Network Identifier option
    carried in the Proxy Binding Update.  However, if the mobile
    access gateway is unable to obtain the Network-Identifier, then it
    MUST NOT include this sub-option.  For including the Network-
    Identifier sub-option, the mobile access gateway needs to be aware
    of the Network Name of the access network (e.g., SSID in the case
    of a WLAN access network) to which the mobile node is attached.

Gundavelli, et al. Standards Track [Page 11] RFC 6757 Access Network Identifier Option October 2012

    This sub-option also includes the Access-Point Name for carrying
    the name of the access point to which the mobile node is attached.
    The Access-Point Name is specially important for applying location
    services, given that the Network Name (e.g., SSID) may not provide
    the needed uniqueness for identifying a location.  When included,
    this sub-option MUST be constructed as described in Section 3.1.1
 o  If the protocol configuration variable EnableANISubOptGeoLocation
    (Section 6) is set to a value of (1), the mobile access gateway
    SHOULD include the Geo-Location sub-option in the Access Network
    Identifier option carried in the Proxy Binding Update.  However,
    if the mobile access gateway is unable to obtain the Geo-location,
    then it MUST NOT include this sub-option.  For including the Geo-
    Location sub-option, the mobile access gateway needs to be aware
    of the GPS coordinates of the network to which the mobile node is
    attached.  When included, this sub-option MUST be constructed as
    described in Section 3.1.2.
 o  If the protocol configuration variable
    EnableANISubOptOperatorIdentifier (Section 6) is set to a value of
    (1), the mobile access gateway SHOULD include the Operator-
    Identifier sub-option in the Access Network Identifier option
    carried in the Proxy Binding Update.  For including the Operator-
    Identifier sub-option, the mobile access gateway needs to be aware
    of the operator identity of that access network.  The access
    network operator SHOULD obtain an identifier from the "Private
    Enterprise Number" registry, in order for the mobile access
    gateway to carry the Operator-Identifier.  If a given access
    network operator has not obtained an identifier from the "Private
    Enterprise Number" registry or if the mobile access gateway is
    unable to learn the operator identity for any other administrative
    reasons, then it MUST NOT include this sub-option.  When included,
    this sub-option MUST be constructed as described in Section 3.1.3.
 If the mobile access gateway had any of the Access Network
 Information mobility options included the Proxy Binding Update sent
 to a local mobility anchor, then the Proxy Binding Acknowledgement
 received from the local mobility anchor SHOULD contain the Access
 Network Information mobility option with the specific sub-options.
 If the mobile access gateway receives a Proxy Binding Acknowledgement
 with a successful Status Value but without an Access Network
 Information mobility option, then the mobile access gateway SHOULD
 log the event and, based on its local policy, MAY proceed to
 terminate the mobility session.  In this case, the mobile access
 gateway knows the local mobility anchor does not understand the
 Access Network Information mobility option and therefore MAY consider
 it as a misconfiguration of the Proxy Mobile IPv6 domain.

Gundavelli, et al. Standards Track [Page 12] RFC 6757 Access Network Identifier Option October 2012

4.2. Local Mobility Anchor Considerations

 o  The conceptual Binding Cache entry data structure maintained by
    the local mobility anchor, described in Section 5.1 of [RFC5213],
    MUST be extended to store the access-network-related information
    elements associated with the current session.  Specifically, the
    following parameters MUST be defined:
    Network-Identifier
    Geo-Location
    Operator-Identifier
 o  On receiving a Proxy Binding Update message [RFC5213] from a
    mobile access gateway with the Access Network Information option,
    the local mobility anchor must process the option and update the
    corresponding fields in the Binding Cache entry.  If the option is
    not understood by that LMA implementation, it will skip the
    option.
 o  If the local mobility anchor understands the Access Network
    Identifier mobility option received in a Proxy Binding Update and
    also supports the sub-option(s), then the local mobility anchor
    MUST echo the Access Network Identifier mobility option with the
    specific sub-option(s) that it accepted back to the mobile access
    gateway in a Proxy Binding Acknowledgement.  The Access Network
    Identifier sub-options defined in this specification MUST NOT be
    altered by the local mobility anchor.
 o  If the received Proxy Binding Update message does not include the
    Access Network Information option, then the mobility session
    associated with that Proxy Binding Update MUST be updated to
    remove any access network information elements.
 o  The local mobility anchor MAY choose to use the Access Network
    Information sub-options for applying any access-operator-specific
    handling or policing of the mobile node traffic.  The specific
    details on how these sub-options are used is outside the scope of
    this document.

Gundavelli, et al. Standards Track [Page 13] RFC 6757 Access Network Identifier Option October 2012

5. IANA Considerations

 Per this document, the following IANA actions have been completed.
 o  Action 1: This specification defines a new mobility header option,
    the Access Network Identifier.  This mobility option is described
    in Section 3.  The type value (52) for this option has been
    assigned from the same numbering space as allocated for the other
    mobility options, as defined in [RFC6275].
 o  Action 2: This specification defines a new mobility sub-option
    format, the Access Network Information (ANI) sub-option.  The
    format of this mobility sub-option is described in Section 3.1.
    This sub-option can be carried in the Access Network Information
    option.  The type value for this sub-option is managed by IANA,
    under the registry "Access Network Information (ANI) Sub-Option
    Type Values".  This specification reserves the following type
    values.  Approval of new Access Network Information (ANI) sub-
    option type values are to be made through IANA Expert Review.
    +=========================================================+
    | 0 | Reserved                                            |
    +=========================================================+
    | 1 | Network-Identifier sub-option                       |
    +=========================================================+
    | 2 | Geo-Location sub-option                             |
    +=========================================================+
    | 3 | Operator-Identifier sub-option                      |
    +=========================================================+
 o  Action 3: This specification defines a new mobility sub-option,
    the Operator-Identifier sub-option.  The format of this mobility
    sub-option is described in Section 3.1.3.  The Operator-Identifier
    (Op-ID) Type field of this sub-option introduces a new number
    space.  This number space is managed by IANA, under the registry
    "Operator-Identifier Type Registry".  This specification reserves
    the following type values.  Approval of new Operator-Identifier
    type values are to be made through IANA Expert Review.
    +===============================================+
    | 0 | Reserved                                  |
    +===+===========================================+
    | 1 | Operator-Identifier as a variable-length  |
    |   | Private Enterprise Number (PEN)           |
    +===+===========================================+
    | 2 | Realm of the Operator                     |
    +===+===========================================+

Gundavelli, et al. Standards Track [Page 14] RFC 6757 Access Network Identifier Option October 2012

6. Protocol Configuration Variables

 This specification defines the following configuration variables that
 control the use of sub-options related to the Access Network
 Information in Proxy Mobile IPv6 signaling messages.  The mobility
 entities, local mobility anchor, and mobile access gateway MUST allow
 these variables to be configured by the system management.  The
 configured values for these protocol variables MUST survive server
 reboots and service restarts.
 EnableANISubOptNetworkIdentifier
    This flag indicates the operational state of the Network-
    Identifier sub-option support.  This configuration variable is
    available at both the mobile access gateway and the local mobility
    anchor.  The default value for this flag is set to (0), indicating
    that support for the Network-Identifier sub-option is disabled.
    When this flag on the mobile access gateway is set to a value of
    (1), the mobile access gateway SHOULD include this sub-option in
    the Proxy Binding Update messages that it sends to the local
    mobility anchor; otherwise, it SHOULD NOT include the sub-option.
    There can be situations where the mobile access gateway is unable
    to obtain the Network-Identifier and may not be able to construct
    this sub-option.
    Similarly, when this flag on the local mobility anchor is set to a
    value of (1), the local mobility anchor SHOULD enable support for
    this sub-option; otherwise, it SHOULD ignore this sub-option.
 EnableANISubOptGeoLocation
    This flag indicates the operational state of the Geo-Location sub-
    option support.  This configuration variable is available at both
    the mobile access gateway and the local mobility anchor.  The
    default value for this flag is set to (0), indicating that support
    for the Geo-Location sub-option is disabled.
    When this flag on the mobile access gateway is set to a value of
    (1), the mobile access gateway SHOULD include this sub-option in
    the Proxy Binding Update messages that it sends to the local
    mobility anchor; otherwise, it SHOULD NOT include the sub-option.
    There can be situations where the mobile access gateway is unable
    to obtain the geo-location information and may not be able to
    construct this sub-option.

Gundavelli, et al. Standards Track [Page 15] RFC 6757 Access Network Identifier Option October 2012

    Similarly, when this flag on the local mobility anchor is set to a
    value of (1), the local mobility anchor SHOULD enable support for
    this sub-option; otherwise, it SHOULD ignore this sub-option.
 EnableANISubOptOperatorIdentifier
    This flag indicates the operational state of the Operator-
    Identifier sub-option support.  This configuration variable is
    available at both the mobile access gateway and the local mobility
    anchor.  The default value for this flag is set to (0), indicating
    that support for the Operator-Identifier sub-option is disabled.
    When this flag on the mobile access gateway is set to a value of
    (1), the mobile access gateway SHOULD include this sub-option in
    the Proxy Binding Update messages that it sends to the local
    mobility anchor; otherwise, it SHOULD NOT include the sub-option.
    There can be situations where the mobile access gateway is unable
    to obtain the Operator-Identifier information and may not be able
    to construct this sub-option.
    Similarly, when this flag on the local mobility anchor is set to a
    value of (1), the local mobility anchor SHOULD enable support for
    this sub-option; otherwise, it SHOULD ignore this sub-option.

7. Security Considerations

 The Access Network Information 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 [RFC6275] and does not require any special
 security considerations.
 The Geo-Location sub-option carried in the Access Network Information
 option exposes the geo-location of the network to which the mobile
 node is attached.  This information is considered to be very
 sensitive, so care must be taken to secure the Proxy Mobile IPv6
 signaling messages when carrying this sub-option.  The base Proxy
 Mobile IPv6 specification [RFC5213] specifies the use of IPsec for
 securing the signaling messages, and those mechanisms can be enabled
 for protecting this information.  Operators can potentially apply
 IPsec Encapsulating Security Payload (ESP) with confidentiality and
 integrity protection for protecting the location information.
 Access-network-specific information elements that the mobile access
 gateway sends may have been dynamically learned over DHCP or using
 other protocols.  If proper security mechanisms are not in place, the
 exchanged information may be potentially compromised with the mobile
 access gateway sending incorrect access network parameters to the

Gundavelli, et al. Standards Track [Page 16] RFC 6757 Access Network Identifier Option October 2012

 local mobility anchor.  This situation may potentially result in
 incorrect service policy enforcement at the local mobility anchor and
 impact to other services that depend on this access network
 information.  This threat can be mitigated by ensuring the
 communication path between the mobile access gateway and the access
 points is properly secured by the use of IPsec, Transport Layer
 Security (TLS), or other security protocols.

8. Acknowledgements

 The authors would like to thank Basavaraj Patil, Carlos Bernardos,
 Gerardo Gieratta, Eric Voit, Hidetoshi Yokota, Ryuji Wakikawa,
 Sangram Kishore, William Wan, Stefano Faccin, and Brian Haberman for
 all the discussions related to this topic.  The authors would also
 like to acknowledge the IESG reviews from Benoit Claise, Stephen
 Farrell, Pete Resnick, Robert Spark, Martin Thomson, and Ralph Droms.

9. References

9.1. Normative References

 [RFC1035]  Mockapetris, P., "Domain names - implementation and
            specification", STD 13, RFC 1035, November 1987.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, November 2003.
 [RFC5139]  Thomson, M. and J. Winterbottom, "Revised Civic Location
            Format for Presence Information Data Format Location
            Object (PIDF-LO)", RFC 5139, February 2008.
 [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.

Gundavelli, et al. Standards Track [Page 17] RFC 6757 Access Network Identifier Option October 2012

9.2. Informative References

 [ANI]      3GPP2 TSG-A, "Interoperability Specification (IOS) for
            High Rate Packet Data (HRPD) Radio Access Network
            Interfaces with Session Control in the Access Network",
            A.S0008-A v3.0, October 2008.
 [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
            (IPv6) Specification", RFC 2460, December 1998.
 [RFC3046]  Patrick, M., "DHCP Relay Agent Information Option",
            RFC 3046, January 2001.
 [RFC6225]  Polk, J., Linsner, M., Thomson, M., and B. Aboba, "Dynamic
            Host Configuration Protocol Options for Coordinate-Based
            Location Configuration Information", RFC 6225, July 2011.
 [SMI]      IANA, "PRIVATE ENTERPRISE NUMBERS", SMI Network Management
            Private Enterprise Codes,
            <http://www.iana.org/assignments/enterprise-numbers>.
 [TS23003]  3GPP, "Numbering, addressing and identification", 3GPP
            TS 23.003 3.15.0, 2012.
 [TS23203]  3GPP, "Policy and Charging Control Architecture", 3GPP
            TS 23.203 10.7.0, 2012.
 [TS23402]  3GPP, "Architecture enhancements for non-3GPP accesses",
            3GPP TS 23.402 10.7.0, 2012.
 [WGS84]    NIMA, "World Geodetic System 1984", Third Edition,
            NIMA TR8350.2, June 2004.

Gundavelli, et al. Standards Track [Page 18] RFC 6757 Access Network Identifier Option October 2012

Authors' Addresses

 Sri Gundavelli (editor)
 Cisco
 170 West Tasman Drive
 San Jose, CA  95134
 USA
 EMail: sgundave@cisco.com
 Jouni Korhonen (editor)
 Nokia Siemens Networks
 Linnoitustie 6
 Espoo  FIN-02600
 Finland
 EMail: jouni.nospam@gmail.com
 Mark Grayson
 Cisco
 11 New Square Park
 Bedfont Lakes, Feltham  TW14 8HA
 England
 EMail: mgrayson@cisco.com
 Kent Leung
 Cisco
 170 West Tasman Drive
 San Jose, CA  95134
 USA
 EMail: kleung@cisco.com
 Rajesh Pazhyannur
 Cisco
 170 West Tasman Drive
 San Jose, CA  95134
 USA
 EMail: rpazhyan@cisco.com

Gundavelli, et al. Standards Track [Page 19]

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