PMIPv6 ANI Extensions: Extensions to the Proxy Mobile IPv6 (PMIPv6) Access Network Identifier Option

Internet Engineering Task Force (IETF)                     R. Pazhyannur
Request for Comments: 7563                                   S. Speicher
Updates: 6757                                              S. Gundavelli
Category: Standards Track                                  Cisco Systems
ISSN: 2070-1721                                              J. Korhonen
                                                    Broadcom Corporation
                                                       J. Kaippallimalil
                                                                  Huawei
                                                               June 2015


 Extensions to the Proxy Mobile IPv6 (PMIPv6) Access Network Identifier
                                 Option

Abstract

   The Access Network Identifier (ANI) mobility option was introduced in
   RFC 6757, "Access Network Identifier (ANI) Option for Proxy Mobile
   IPv6".  This enables a Mobile Access Gateway (MAG) to convey
   identifiers like the network identifier, geolocation, and operator
   identifier.  This specification extends the Access Network Identifier
   mobility option with sub-options to carry the civic location and the
   MAG group identifier.  This specification also defines an ANI Update-
   Timer sub-option that determines when and how often the ANI option
   will be updated.

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/rfc7563.

Copyright Notice

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

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   4
     2.1.  Conventions . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Protocol Extension  . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Civic-Location Sub-Option . . . . . . . . . . . . . . . .   5
     3.2.  MAG-Group-Identifier Sub-Option . . . . . . . . . . . . .   6
     3.3.  ANI Update-Timer Sub-Option . . . . . . . . . . . . . . .   6
   4.  Protocol Considerations . . . . . . . . . . . . . . . . . . .   7
     4.1.  MAG Considerations  . . . . . . . . . . . . . . . . . . .   7
     4.2.  LMA Considerations  . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   "Access Network Identifier (ANI) Option for Proxy Mobile IPv6"
   [RFC6757] introduced the ANI mobility option.  This enabled a Mobile
   Access Gateway (MAG) to provide the Network-Identifier, Geo-Location,
   and Operator-Identifier sub-options.  When the access network is
   WLAN, the Network-Identifier sub-option may contain the Service Set
   Identifier (SSID) and the Basic Service Set Identifier (BSSID) of the
   Access Point (AP) and the geolocation of the AP, and the Operator-
   Identifier may contain the realm of the operator managing the WLAN.
   The MAG sends the above information to the Local Mobility Anchor
   (LMA).  The LMA may use this information to determine access-network-
   specific policies (in terms of Quality of Service (QoS), Deep Packet
   Inspection (DPI), etc.).  Further, the LMA may make this information
   available to location-based applications.

   While the above mentioned sub-options provide a rich set of
   information, in this document we describe the need for extending the
   ANI sub-options that are particularly useful in WLAN deployments.  In
   WLAN deployments (especially indoor AP deployments), it is difficult
   to provide geospatial coordinates of APs.  At the same time, for many
   location-based applications the civic location is sufficient.  This
   motivates the need for an ANI Civic-Location sub-option.  In many
   deployments, operators tend to create groups of APs into "AP-Groups".
   These groups have a group identifier.  The group identifier is used
   as a proxy for coarse location (such as the floor of a building or a
   small building).  The group identifier may also be used to provide a
   common policy (e.g., QoS, charging, DPI) for all APs in that group.
   This specification provides a sub-option for the MAG to convey a
   group identifier to the LMA.  The provisioning of the group
   identifier is outside the scope of this specification and is
   typically done via a configuration mechanism such as CLI (Command-
   line Interface) or via Control and Provisioning of Wireless Access
   Points (CAPWAP) [RFC5415] [RFC5416].

   This document also provides a new sub-option that determines how
   often the MAG will update the ANI.  In typical deployments, it is
   expected that the MAG will update the ANI as soon as it changes.
   This is certainly true when the MAG is co-located with the AP.  When
   a client roams from one AP to another AP, the MAG on the roamed (or
   sometimes referred to as the target) AP will provide the new ANI (for
   example, the network identifier and geolocation of the new AP).
   However, if the MAG is co-located with an Access Controller (also
   known as Wireless LAN Controller (WLC)), then a client roaming from
   one AP to another AP does not necessarily perform an ANI update.  The
   WLC handles client mobility between APs and as a result, intra-WLC
   mobility is hidden from the LMA.

   In such deployments, the information conveyed in the ANI sub-options
   (e.g., location) becomes stale and is only refreshed at the time of
   lifetime expiry.  The MAG could deal with this by sending a Proxy
   Binding Update (PBU) whenever a client moves between APs just for the
   purpose of updating the ANI sub-option.  Alternately, this document
   allows the LMA to determine how often it wants to know about the
   changes in the ANI sub-option; for example, in some cases the LMA may
   not care about the ANI sub-option except at the time of initial
   binding, or in some cases it may care about every AP transition.  The
   sub-option allows the LMA to tell the MAG the desired update
   frequency.  As always, mobility events or re-registration events will
   update the ANI sub-options.  The LMA can use the ANI Update-Timer
   option to set the maximum frequency at which it wants to receive ANI
   updates.  This is particularly useful in environments where a MAG
   covers a large number of Wi-Fi APs and there is high client mobility
   between the APs; for example, in a stadium Wi-Fi deployment, if a LMA
   does not want ANI updates any more often than 100 seconds, then it
   can propose 100 seconds as the value for ANI Update-Timer.

   [RFC6757] provides ANI sub-options to carry geolocation information.
   In this document, we provide additional sub-options to carry the
   civic location and group identifier.  This document also defines an
   ANI sub-option to enable a MAG to communicate how often the MAG will
   update the ANI information.

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 of the mobility-related terms used in this document are to be
   interpreted as defined in [RFC5213] and [RFC5844].  In this document,
   Civic Location is defined as follows.

      Civic Location: There are two common ways to identify the location
      of an object, either through geospatial coordinates or by so-
      called civic addresses.  Geospatial coordinates indicate
      longitude, latitude, and altitude, while civic addresses indicate
      a street address or sometimes the location within a building (such
      as a room number).  Civic location refers to the civic address.

3.  Protocol Extension

3.1.  Civic-Location Sub-Option

   The Civic-Location is a mobility sub-option carried in the Access
   Network Identifier option defined in [RFC6757].  This sub-option
   carries the civic location information of the mobile node as known to
   the MAG.  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=4     |  ANI Length   |   Format      | Reserved      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            civic location                                     ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 1: Civic-Location Sub-Option

   ANI Type:  4

   ANI Length:  Total length of this sub-option in octets, excluding the
      ANI Type and ANI Length fields.

   Format:  This specifies the encoding format of the civic location.
      The value 0 is defined in this specification as described below.
      The remaining values (1 through 255) are reserved.

            0: This value denotes Binary Encoding.  The location format
            is based on the encoding format defined in Section 3.1 of
            [RFC4776], whereby the first 3 octets are not put into the
            civic location field (i.e., the code for the DHCP option,
            the length of the DHCP option, and the 'what' element are
            not included).  What is included is the two-octet country
            code field, followed by one or more civic address elements.
            The country-code is a two-letter ISO 3166 country code in
            capital ASCII letters, e.g., US.  The structure of the civic
            address elements that follow the country code field is as
            defined in Section 3.3 of [RFC4776].

   Reserved:  This MUST be set to zero when sending and ignored when
      received.

   civic location:  This field will contain the civic location.  The
      format (encoding) type is specified in the format field of this
      sub-option.  Note that the length SHALL NOT exceed 253 bytes.

3.2.  MAG-Group-Identifier Sub-Option

   The MAG group identifier is a mobility sub-option carried in the
   Access Network Identifier option defined in [RFC6757].  The MAG group
   identifier identifies the group affiliation of the MAG within that
   Proxy Mobile IPv6 domain.  The group identifier is not assumed to be
   globally unique across different network operators.  However, the
   group identifier should be unique within an operator network.  In
   domains spanning multiple operators, it is recommended that the
   Operator-Identifier sub-option (defined in [RFC6757]) be used in
   addition to the MAG-Group-Identifier sub-option to ensure uniqueness.
   When the MAG is configured with a group identifier, the MAG should
   send its group identifier in the PBU.  Note that the configuration of
   this identifier is outside the scope of this specification; the usage
   of the identifier by the LMA is left to implementation.  The format
   of this sub-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=5     |  ANI Length   |  group identifier             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 2: MAG-Group-Identifier Sub-Option

   ANI Type:  5

   ANI Length:  Total length of this sub-option in octets, excluding the
      ANI Type and ANI Length fields.  The value is always 2.

   group identifier:  This is a 3-octet unsigned integer value assigned
      to a group of MAGs.

3.3.  ANI Update-Timer Sub-Option

   The ANI Update-Timer is a mobility sub-option carried in the ANI
   option defined in [RFC6757].  Section 4 describes how the MAG and LMA
   use this sub-option.

    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=6     |  ANI Length   |       Update-Timer            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 3: ANI Update-Timer Sub-Option

   ANI Type:  6

   ANI Length:  Total length of this sub-option in octets, excluding the
      ANI Type and ANI Length fields.  The value is always 2.

   Update-Timer:  Update-Timer is a 16-bit unsigned integer.  The unit
      of time is 4 seconds (time unit of 4 seconds ensures consistency
      with the time units for the binding lifetime).  A value of 0
      indicates that the MAG will send an updated ANI mobility option as
      soon as it discovers a change in ANI values.  A non-zero value
      indicates that the MAG may not send ANI values immediately after
      they have changed but rather send ANI updates when the
      Update-Timer expires.

4.  Protocol Considerations

   The following considerations apply to the LMA and the MAG.

4.1.  MAG Considerations

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

      *  civic location

      *  MAG group identifier

      *  ANI Update-Timer

   o  If the mobile access gateway is configured to support the Access
      Network Information sub-options defined in this specification, it
      includes this option with the specific sub-options in all PBU
      messages (including PBUs for lifetime extension and for
      deregistration) that it sends to the LMA.  The Access Network
      Information option is constructed as specified in Section 3.

   o  ANI Update-Timer Considerations: The MAG sets the Update-Timer
      based on an exchange of timer values with the LMA.  When the ANI
      Update-Timer sub-option is carried in a PBU, it is considered as a
      proposed value for the Update-Timer.  The LMA may change the value
      of the Update-Timer received in the PBU.  When the LMA-provided
      value for the Update-Timer is different than what is sent by the
      MAG, the MAG should use the LMA-provided value.  If the MAG does
      not receive an ANI Update-Timer sub-option in the Proxy Binding
      Acknowledgement (PBA) (in response to sending the sub-option in
      the PBU), then MAG behavior is in accordance to [RFC6757].  When
      ANI parameters of a mobility session change, the MAG checks
      whether the Update-Timer has expired.  If the Update-Timer has
      expired, the MAG sends a PBU with the ANI option.  The ANI option
      reflects the updated access network parameters for that mobility
      session.  If the Update-Timer has not expired, the MAG does not
      send a PBU.  When the Update-Timer for a mobility session expires,
      the MAG checks whether the ANI parameters have changed.  If the
      parameters have changed from the last reported values, the MAG
      sends a PBU with an ANI option.  If the parameters have not
      changed, the MAG does not send a PBU (and the Update-Timer remains
      expired).  Note that the MAG may send a PBU even before the
      Update-Timer expires.  This could be, for example, to initiate a
      QoS service request to the LMA (see [RFC7222]).  In such cases,
      the MAG must reset the Update-Timer when it sends a PBU.

   o  If the mobile access gateway had any of the Access Network
      Information mobility options included in the PBU sent to an LMA,
      then the PBA received from the LMA should contain the Access
      Network Information mobility option with the specific sub-options.
      If the mobile access gateway receives a PBA with a successful
      Status Value but without an Access Network Information mobility
      option, then the mobile access gateway may log the event and,
      based on its local policy, even proceed to terminate the mobility
      session.  In this case, the mobile access gateway knows the LMA
      does not understand the Access Network Information mobility
      option.

4.2.  LMA Considerations

   o  The conceptual Binding Cache entry data structure maintained by
      the LMA, described in Section 5.1 of [RFC5213], is extended to
      store the access-network-related information elements associated
      with the current session.  Specifically, the following parameters
      are defined:

      *  civic location

      *  MAG group identifier

      *  ANI Update-Timer

   o  On receiving a PBU message from a MAG with the ANI option, the LMA
      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 and process the PBU
      without these options.

   o  If the received PBU message does not include the Access Network
      Information option, then the mobility session associated with that
      PBU is updated to remove any access network information elements.

   o  If the LMA understands/supports the Access Network Identifier
      mobility sub-options defined in this specification, then the LMA
      echoes the Access Network Identifier mobility option with the
      specific sub-option(s) that it accepted back to the mobile access
      gateway in a PBA.  The Civic-Location and MAG-Group-Identifier
      sub-options defined in this specification should not be altered by
      the LMA.  The LMA may change the value of the ANI Update-Timer
      sub-option.  It may choose to either echo the same value or
      increase or decrease the timer value.  For example, if the LMA
      does not want to receive frequent updates (as implied by the timer
      value), it may choose to increase the value.  Similarly, if the
      LMA needs to receive ANI updates as soon as possible, then it may
      set the value to zero (0) in the PBA.

5.  IANA Considerations

   IANA has registered the values described below.

   o  This specification defines a new Access Network Identifier sub-
      option called the Civic-Location sub-option.  This mobility sub-
      option is described in Section 3.1 and this sub-option can be
      carried in the Access Network Identifier mobility option.  The
      type value <4> has been allocated from the registry "Access
      Network Information (ANI) Sub-Option Type Values".

   o  This specification defines a new Access Network Identifier sub-
      option called the MAG-Group-Identifier sub-option.  This mobility
      sub-option is described in Section 3.2 and this sub-option can be
      carried in Access Network Identifier mobility option.  The type
      value <5> has been allocated from the registry "Access Network
      Information (ANI) Sub-Option Type Values".

   o  This specification defines a new Access Network Identifier sub-
      option called the ANI Update-Timer sub-option.  This sub-option is
      described in Section 3.3 and this sub-option can be carried in the
      Access Network Identifier mobility option.  The type value <6> has
      been allocated from the registry "Access Network Information (ANI)
      Sub-Option Type Values".

6.  Security Considerations

   The Civic-Location sub-option defined in this specification is
   carried in the Access Network Identifier option defined in [RFC6757].
   This sub-option is carried in PBU and PBA messages.  This sub-option
   is carried like any other Access Network Identifier sub-option as
   defined in [RFC6757].  Therefore, it inherits its security guidelines
   from [RFC5213] and [RFC6757] and does not require any additional
   security considerations.

   The Civic-Location sub-option exposes the civic 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.  The other way to protect the sensitive location
   information of network users is of course to not send it in the first
   place.  Users of the Civic-Location sub-option should provision
   location values with the highest possible level of granularity, e.g.,
   to the province or city level rather than provisioning specific
   addresses.

   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 between the MAG and LMA may be compromised.
   This situation may result in incorrect service policy enforcement at
   the LMA and impact 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.

7.  References

7.1.  Normative References

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

   [RFC4776]  Schulzrinne, H., "Dynamic Host Configuration Protocol
              (DHCPv4 and DHCPv6) Option for Civic Addresses
              Configuration Information", RFC 4776,
              DOI 10.17487/RFC4776, November 2006,
              <http://www.rfc-editor.org/info/rfc4776>.

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
              RFC 5213, DOI 10.17487/RFC5213, August 2008,
              <http://www.rfc-editor.org/info/rfc5213>.

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, DOI 10.17487/RFC5844, May 2010,
              <http://www.rfc-editor.org/info/rfc5844>.

   [RFC6757]  Gundavelli, S., Ed., Korhonen, J., Ed., Grayson, M.,
              Leung, K., and R. Pazhyannur, "Access Network Identifier
              (ANI) Option for Proxy Mobile IPv6", RFC 6757,
              DOI 10.17487/RFC6757, October 2012,
              <http://www.rfc-editor.org/info/rfc6757>.

   [RFC7222]  Liebsch, M., Seite, P., Yokota, H., Korhonen, J., and S.
              Gundavelli, "Quality-of-Service Option for Proxy Mobile
              IPv6", RFC 7222, DOI 10.17487/RFC7222, May 2014,
              <http://www.rfc-editor.org/info/rfc7222>.

7.2.  Informative References

   [RFC5415]  Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
              Ed., "Control And Provisioning of Wireless Access Points
              (CAPWAP) Protocol Specification", RFC 5415,
              DOI 10.17487/RFC5415, March 2009,
              <http://www.rfc-editor.org/info/rfc5415>.

   [RFC5416]  Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
              Ed., "Control and Provisioning of Wireless Access Points
              (CAPWAP) Protocol Binding for IEEE 802.11", RFC 5416,
              DOI 10.17487/RFC5416, March 2009,
              <http://www.rfc-editor.org/info/rfc5416>.

Acknowledgements

   This document benefited considerably from the numerous improvements
   proposed by Kent Leung.

Authors' Addresses

   Rajesh S. Pazhyannur
   Cisco Systems
   170 West Tasman Drive
   San Jose, California  95134
   United States
   EMail: rpazhyan@cisco.com


   Sebastian Speicher
   Cisco Systems
   Richtistrasse 7
   Wallisellen, Zurich  8304
   Switzerland
   EMail: sespeich@cisco.com


   Sri Gundavelli
   Cisco Systems
   170 West Tasman Drive
   San Jose, California  95134
   United States
   EMail: sgundave@cisco.com


   Jouni Korhonen
   Broadcom Corporation
   3151 Zanker Road
   San Jose, California  95134
   United States
   EMail: jouni.nospam@gmail.com


   John Kaippallimalil
   Huawei
   5340 Legacy Drive, Suite 175
   Plano, Texas  75024
   United States
   EMail: john.kaippallimalil@huawei.com