Network Working Group                                        S. Bhandari
Internet-Draft                                             S. Gundavelli
Intended status: Standards Track                           Cisco Systems
Expires: January 9, 2013                                     J. Korhonen
                                                  Nokia Siemens Networks
                                                            July 8, 2012


                Access-Network-Identifer Option in DHCP
            draft-bhandari-dhc-access-network-identifier-00

Abstract

   This document specifies the format and mechanism that is to be used
   for encoding access network identifiers in DHCPv4 and DHCPv6 messages
   by defining a new access network identifier options and sub-options.

Requirements Language

   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].

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 January 9, 2013.

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



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   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.  Motivation . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  DHCPv4 Access-Network-Identifier Option  . . . . . . . . . . .  5
     4.1.  DHCPv4 Access-Network-Identifier Sub-options . . . . . . .  5
       4.1.1.  Access-Network-Type Sub-option . . . . . . . . . . . .  6
       4.1.2.  Network-Identifier Sub-option  . . . . . . . . . . . .  7
       4.1.3.  Operator-Identifier Sub-option . . . . . . . . . . . .  8
   5.  DHCPv6 Access-Network-Identifier Option  . . . . . . . . . . .  9
     5.1.  Access-Network-Type option . . . . . . . . . . . . . . . . 10
     5.2.  Network-Identifier option  . . . . . . . . . . . . . . . . 11
     5.3.  Operator-Identifier option . . . . . . . . . . . . . . . . 12
   6.  Client Behavior  . . . . . . . . . . . . . . . . . . . . . . . 13
   7.  Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . . 13
   8.  Server Behavior  . . . . . . . . . . . . . . . . . . . . . . . 14
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     9.1.  DHCPv4 Access-Network-Identifier Sub-option registry . . . 14
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
   12. Normative References . . . . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16




















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1.  Introduction

   Access network idenfication of a network device has a range of
   application.  The local mobility anchor in a Proxy Mobile IPv6 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 document specifies Dynamic Host Configuration Protocol v4
   (DHCPv4) [RFC2131] and Dynamic Host Configuration Protocol v6
   (DHCPv6) [RFC3315] options for access network identification that is
   added by Client or Relay agent in the DHCPv4 or DHCPv6 messages
   towards the Server.

   Dynamic Host Configuration Protocol (DHCP) client or DHCP relay agent
   aware of the access network and access operator add this information
   in the DHCP messages.  DHCP relay agent or DHCP server in the mobile
   access gateway can pass this information towards local mobility
   anchor either via Proxy Mobile IPv6 signalling or by relaying the
   DHCP messages to DHCP entity within the local mobility anchor.


2.  Motivation

   Proxy mobile IPv6 [RFC5213] can be used for supporting network-based
   mobility management in various type of network deployments.  The
   network architectures, such as Service provider Wi-Fi access
   aggregation or, WLAN integrated 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 PCC [TS23203] and ANDSF [TS23402] in 3GPP system 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 they are attached to a
   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 (SSID) in case of IEEE
   802.11 based access networks.  Other examples of services include the
   operator's ability to apply tariff based on the location.

   The PMIPv6 extension as specified in
   [I-D.ietf-netext-access-network-option] defines PMIPv6 options to
   carry access network identifiers in PMIPv6 signalling from Mobile
   Access Gateway (MAG) to LMA.  MAG can learn this information from
   DHCP options as inserted by DHCP client or Relay agent before MAG.



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   If MAG relays DHCP messages to LMA as specified in [RFC5844] this
   information can be inserted by MAG towards LMA in the forwarded DHCP
   messages.

   Figure 1 illustrates an example Proxy Mobile IPv6 deployment where
   Acess Points (AP) inserts access network identifiers in DHCP
   messages.  The mobile access gateway learns this information over
   DHCP and 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 and the identities of the
   operators running the IEEE 802.11 access network infrastructure.

          SSID: IETF-1
          Operator-Id: provider1.example.com
          +--+ DHCP
          |AP|-------.                        {Access Specific Policies)
          +--+       |             _-----_             |
                   +-----+       _(       )_        +-----+
                   | MAG |-=====(   PMIPv6  )======-| LMA |-
                   +-----+       (_ Tunnel_)        +-----+
          +--+ DHCP  |             '-----'
          |AP|-------'
          +--+
          SSID: IETF-2
          Operator-Id: provider2.example.com


                      Access Networks attached to MAG


3.  Terminology

   All the DHCP related terms used in this document to be interpreted as
   defined in the Dynamic Host Configuration Protocol v4 (DHCPv4)
   [RFC2131] and Dynamic Host Configuration Protocol v6 (DHCPv6)
   [RFC3315] specifications.  DHCP refers to both DHCPv4 and DHCPv6
   messages and entities throughout this document.

   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 from one
   network to the other.




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   Vendor ID The Vendor ID is the SMI Network Management Private
   Enterprise Code of the IANA-maintained Private Enterprise Numbers
   registry [SMI].


4.  DHCPv4 Access-Network-Identifier Option

   Access network identifier option carries information to identify the
   access network to which the client is attached to.  This information
   includes access technology type, network identifier and access
   network operator identifiers.

   The format of the DHCPv4 Access-Network-Identifier option is shown
   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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      OPTION_ACCESS_NETWORK_ID |          option-len           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         suboption-1                           |
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         suboption-2                           |
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         suboption-n                           |
     :                                                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       option-code: 8-bit code OPTION_ACCESS_NETWORK_ID (TBD1),

       option-len: 8 bit indicating total length of the included suboptions.


4.1.  DHCPv4 Access-Network-Identifier Sub-options

   Access network identifier information will be defined in multiple
   sub-options as described in this section.  The initial assignment of
   DHCP OPTION_ACCESS_NETWORK_ID Sub-options is as follows:










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          Sub-option Code            Sub-Option Descrption
          ---------------            ----------------------
                 1                   Access-Network-Type Sub-option
                 2                   Network-Identifier Sub-option
                 3                   Operator-Identifier Sub-option



4.1.1.  Access-Network-Type Sub-option

   This sub-option is used for exchanging the type of the access
   technology by which the client is attached to the network.  There can
   only be a single instance of this specific sub-option in any
   OPTION_ACCESS_NETWORK_ID option.  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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | suboption-code=1 |   Length      |          ATT               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    suboption-code:  8-bit code, it should be set to value of (1),
                      indicating that its a Access-Network-Type sub-option

    Length: 8-bit unsigned integer indicating the length of this suboption
        in octets, excluding the suboption-code and length fields.
        This field MUST be set to 2.


    Access Technology Type (ATT)

        An 16-bit field that specifies the access technology through
        which the client is connected to the access link.

        The values is as populated from the IANA name space
        Access Technology Type Option type values as requested in [RFC5213]

        0: Reserved         ("Reserved")
        1: Virtual          ("Logical Network Interface")
        2: PPP              ("Point-to-Point Protocol")
        3: IEEE 802.3       ("Ethernet")
        4: IEEE 802.11a/b/g ("Wireless LAN")
        5: IEEE 802.16e     ("WIMAX")








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4.1.2.  Network-Identifier Sub-option

   This sub-option can be used for carrying the name of the access
   network (e.g., a SSID in case of IEEE 802.11 Access Network, or PLMN
   Identifier [TS23003] in case of 3GPP access ), to which the client is
   attached.  There can only be a single instance of this specific sub-
   option in any OPTION_ACCESS_NETWORK_ID 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | suboption code=2|   Length    |E|   Reserved  | Net-Name Len  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Network Name (e.g., SSID or PLMNID)       ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | AP-Name Len   |        Access-Point Name                      ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  suboption code:  8-bit code, it should be set to value of (2),
                   indicating that its a Network-Identifier sub-option

  Length:  8-bit indicating Total length of this sub option,
           excluding the suboption code and length fields.
           The value can be in the range of 2 to 32 octets.

  'E'-bit:  1-bit flag for representing the encoding of the following
      name field.  MUST be set to zero (0) if the network name is
      encoded using 8-bit octets or to one (1) if the network name is
      encoded using UTF-8.

   Reserved:  7 bits 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 to be followed.

   Network Name:  The name of the access network to which the client
      is attached.  The type of the network-name is dependent on
      the Access Technology to which the mobile node is attached.  If
      its 802.11 access, the network-name is 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 MNC and MCC codes MUST be
      3 digists.  If the MNC in use only has 2 digits, then it MUST be
      preceded with a '0'.  Encoding MUST be UTF-8.



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   AP-Name Length:  8-bit field for representing the length of the
      access point name to be followed.  If the access point name is not
      carried, this length should be set to zero.

   Access-Point Name:  The name of the access point (physical device
      name) to which the client is attached.  This is the
      identifier that uniquely identifies the access point.  In some
      deployments the name can be set to the mac-address of the device.
      The string is carried in UTF-8 representation.


4.1.3.  Operator-Identifier Sub-option

   The Operator-Identifier sub-option can be used for carrying the
   operator identifier of the access network to which the client is
   attached.  There can only be a single instance of this specific sub-
   option in any OPTION_ACCESS_NETWORK_ID option.  The format of this
   option is defined below.

































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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | suboption code=3 |        Length   |   Op-ID Type      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            Operator Identifier                    ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   suboption code:  8 bit code, It should be set to value of (3),
                  indicating that it is Operator-Identifier sub-option

   Length:  Total length of this sub option, excluding the suboption code
      and 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 -  Vendor ID as a four octet Private Enterprise Number [SMI].

      2 -  Realm of the operator.  Realm names are required to be
         unique, and are piggybacked on the administration of the DNS
         namespace.  Realms are encoded using a domain name encoding
         defined in [RFC1035].

   Operator Identifier:  Up to 253 octets of the operator identifier.
      The encoding of the identifier depends on the used Operator-ID
      Type.  Numeric values are encoded in network byte order and
      strings have no terminating '\0' mark.




5.  DHCPv6 Access-Network-Identifier Option















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   The format of the DHCPv6 Access-Network-Information option is shown
   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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Option Code (TBD2)      |            OptLen             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Access-Network-ID options                    +
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   option-code:                OPTION_DHCPV6_ACCESS_NETWORK_ID (TBD2)
   option-length:              Total length in octets of all the options
                               in Access-Network-ID options
   Access-Network-ID options:  Access network identifier options as defined in
                               this section


5.1.  Access-Network-Type option

   This option is used for exchanging the type of the access technology
   by which the client is attached to the network.  There can only be a
   single instance of this specific option in any
   OPTION_DHCPV6_ACCESS_NETWORK_ID option.  Its format is as follows:



























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     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Option Code (TBD3)      |            OptLen             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       ATT                                     +
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   option-code:        16-bit code OPTION_ANI_ATT (TBD3)
   option-length:      16-bit unsigned integer indicating length
                       in octets of this option
   Access Technology Type (ATT)

        An 16-bit field that specifies the access technology through
        which the client is connected to the access link.

        The values is as populated from the IANA name space
        Access Technology Type Option type values as requested in [RFC5213]

        0: Reserved         ("Reserved")
        1: Virtual          ("Logical Network Interface")
        2: PPP              ("Point-to-Point Protocol")
        3: IEEE 802.3       ("Ethernet")
        4: IEEE 802.11a/b/g ("Wireless LAN")
        5: IEEE 802.16e     ("WIMAX")



5.2.  Network-Identifier option

   This option can be used for carrying the name of the access network
   (e.g., a SSID in case of IEEE 802.11 Access Network, or PLMN
   Identifier [TS23003] in case of 3GPP access ), to which the client is
   attached.  There can only be a single instance of this specific sub-
   option in any OPTION_DHCPV6_ACCESS_NETWORK_ID 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Option Code (TBD4)      |            OptLen             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |E|   Reserved      | Net-Name Len      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        Network Name (e.g., SSID or PLMNID)        ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | AP-Name Len   |        Access-Point Name                      ~



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code:        16-bit code OPTION_ANI_NETWORK_ID (TBD4)
   option-length:      16-bit unsigned integer indicating length
                       in octets of this option.The value can be in the
                       range of 2 to 32 octets.

   'E'-bit:  1-bit flag for representing the encoding of the following
      name field.  MUST be set to zero (0) if the network name is
      encoded using 8-bit octets or to one (1) if the network name is
      encoded using UTF-8.

   Reserved:  7 bits 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 to be followed.

   Network Name:  The name of the access network to which the client
      is attached.  The type of the network-name is dependent on
      the Access Technology to which the mobile node is attached.  If
      its 802.11 access, the network-name is 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 MNC and MCC codes MUST be
      3 digists.  If the MNC in use only has 2 digits, then it MUST be
      preceded with a '0'.  Encoding MUST be UTF-8.

   AP-Name Length:  8-bit field for representing the length of the
      access point name to be followed.  If the access point name is not
      carried, this length should be set to zero.

   Access-Point Name:  The name of the access point (physical device
      name) to which the client is attached.  This is the
      identifier that uniquely identifies the access point.  In some
      deployments the name can be set to the mac-address of the device.
      The string is carried in UTF-8 representation.


5.3.  Operator-Identifier option

   The Operator-Identifier option can be used for carrying the operator
   identifier of the access network to which the client is attached.
   There can only be a single instance of this specific option in any
   OPTION_DHCPV6_ACCESS_NETWORK_ID option.  Its format is as follows:




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    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Option Code (TBD5)      |            OptLen             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Op-ID Type      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Operator Identifier                    ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    option-code:        16-bit code OPTION_ANI_OPERATOR_ID (TBD5)
    option-length:      16-bit unsigned integer indicating length
                        in octets of this option.

    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 -  Vendor ID as a four octet Private Enterprise Number [SMI].

       2 -  Realm of the operator.  Realm names are required to be
          unique, and are piggybacked on the administration of the DNS
          namespace.  Realms are encoded using a domain name encoding
          defined in [RFC1035].

    Operator Identifier:  Up to 253 octets of the operator identifier.
       The encoding of the identifier depends on the used Operator-ID
       Type.  Numeric values are encoded in network byte order and
       strings have no terminating '\0' mark.




6.  Client Behavior

   All hosts or clients MAY include access network identifier options in
   all the upstream DHCP messages to inform the receiver about the
   access network it is attached to.


7.  Relay Agent Behavior

   DHCP Relay Agents MAY include these options before forwarding the
   DHCP message to provide information about the access network over
   which DHCP messages from the client is received.



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8.  Server Behavior

   If DHCP Server is unable to understand this option it MUST be
   ignored.  There is no requirement that a server return this option
   and its data in a downstream DHCP message.


9.  IANA Considerations

   This document defines DHCPv4 Access Network Identifier option which
   requires assignment of DHCPv4 option code TBD1 assigned from "Bootp
   and DHCP options" registry (http://www.iana.org/assignments/
   bootp-dhcp-parameters/bootp-dhcp-parameters.xml), as specified in
   [RFC2939].

   IANA is requested to assign option codes for the following DHCPv6
   options from the "DHCPv6 and DHCPv6 options" registry (http://
   www.iana.org/assignments/dhcpv6-parameters/dhcpv6-parameters.xml).

          Option Code             Descrption
          ---------------   ----------------------
              TBD2           OPTION_DHCPV6_ACCESS_NETWORK_ID
              TBD3           OPTION_ANI_ATT
              TBD4           OPTION_ANI_NETWORK_ID
              TBD5           OPTION_ANI_OPERATOR_ID

9.1.  DHCPv4 Access-Network-Identifier Sub-option registry

   IANA is required to maintain a new number space of "DHCPv4 Access
   Network Identifier Sub-options", with the initial sub-options as
   described in this document.  IANA assigns future DHCPv4 Access
   Network Identifier Sub-options with a "IETF Consensus" policy as
   described in [RFC2434].  Future proposed sub-options are to be
   referenced symbolically in the internet-drafts that describe them,
   and shall be assigned numeric codes by IANA when and if the draft is
   approved by IESG for Proposed Standard RFC status.


10.  Security Considerations

   Since there is no privacy protection for DHCP messages, an
   eavesdropper who can monitor the link between the DHCP server, relay
   agent and client can discover access network information.

   To minimize the unintended exposure of this information, this option
   SHOULD be included by DHCP entities only when it is configured.
   Where critical decisions might be based on the value of this option,
   DHCP authentication as defined in "Authentication for DHCP Messages"



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   [RFC3118] and "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"
   [RFC3315] SHOULD be used to protect the integrity of the DHCP
   options.  Link-layer confidentiality and integrity protection may
   also be employed to reduce the risk of disclosure and tampering.

   Security issues related DHCPv6 are described in section 23 of
   [RFC3315].


11.  Acknowledgements


12.  Normative References

   [ANI]      "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.

   [I-D.ietf-netext-access-network-option]
              Gundavelli, S., Korhonen, J., Grayson, M., Leung, K., and
              R. Pazhyannur, "Access Network Identifier (ANI) Option for
              Proxy Mobile IPv6",
              draft-ietf-netext-access-network-option-08 (work in
              progress), April 2012.

   [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.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC2939]  Droms, R., "Procedures and IANA Guidelines for Definition
              of New DHCP Options and Message Types", BCP 43, RFC 2939,
              September 2000.

   [RFC3118]  Droms, R. and W. Arbaugh, "Authentication for DHCP
              Messages", RFC 3118, June 2001.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for



Bhandari, et al.         Expires January 9, 2013               [Page 15]


Internet-Draft           DHCPv4 & v6 ANI options               July 2012


              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [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.

   [SMI]      "PRIVATE ENTERPRISE NUMBERS, SMI Network Management
              Private Enterprise Codes", February  2011.

   [TS23003]  "Numbering, addressing and identification", 2011.

   [TS23203]  "Policy and Charging Control Architecture", 2012.

   [TS23402]  "Architecture enhancements for non-3GPP accesses", 2012.


Authors' Addresses

   Shwetha Bhandari
   Cisco Systems
   Cessna Business Park, Sarjapura Marathalli Outer Ring Road
   Bangalore, KARNATAKA  560 087
   India

   Phone: +91 80 4426 0474
   Email: shwethab@cisco.com


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

   Email: sgundave@cisco.com


   Jouni Korhonen
   Nokia Siemens Networks
   Linnoitustie 6
   FIN-02600 Espoo,
   Finland

   Phone:
   Email: jouni.nospam@gmail.com




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