[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 RFC 6153

Internet Engineering Task force                              Subir Das
Internet Draft                                  Telcordia Technologies
Intended Status: Proposed Standard                         Gabor Bajko
Expires: Jan 11, 2010                                            Nokia
                                                          July 12, 2009


Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Options for
Access Network Discovery and Selection Function(ANDSF) Discovery
                    draft-das-mipshop-andsf-dhcp-options-01

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on January 11, 2010.

Copyright and License Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.


Abstract

   This document defines new Dynamic Host Configuration Protocol
   (DHCPv4 and DHCPv6) options that contain a list IP addresses and a
   list of domain names that can be mapped to ANDSF (Access Network

S Das & G. Bajko          Expires 01/11/10                  [Page 1]

ANDSF DHCP Options                                      July  2009

   Discovery and Selection Function) entities in an IP network. ANDSF
   is being developed in 3GPP (Release-8) and provides inter-system
   mobility policies and access network specific information to the
   mobile nodes(MNs) [3GPPTS23.402].


Table of Contents

   1. Introduction .................................................2
   2. ANDSF IPv4 address option for DHCPv4..........................3
   3. ANDSF Domain Name List option for DHCPv4......................4
   4. ANDSF IPv6 address option for DHCPv6..........................5
   5. ANDSF Domain Name List option for DHCPv6......................6
   6. Option Usage..................................................7
        6.1 Usage of ANDSF Options for DHCPv4.......................7
        6.2 Usage of ANDSF Options for DHCPv6.......................7
   7. Security Considerations ......................................8
   8. IANA Considerations ..........................................8
   9. Acknowledgements .............................................9
   10. References ..................................................9
       10.1 Normative References ...................................9
       10.2 Informative References ................................10
   Author's Addresses .............................................10

(1) Conventions used in this document

   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.

 (2) Terminology and abbreviations used in this document

   ANDSF (Access Network Discovery and Selection Function): An entity
   that contains data management and control functionality and provides
   necessary network discovery and selection assistance data to the
   user entity (UE) as per operator policy [3GPP TS 23.402].

   Access Network: A network that is accessed by the user entity(UE)

   3GPP Network : Third Generation Partnership Project specified network

   Non-3GPP Network: Network that is not specified by 3GPP network
   (e.g., CDMA network)


1. Introduction

    Access Network Discovery and Selection Function (ANDSF) is being
    defined in 3GPP (Release-8) to provide necessary network discovery
    and selection assistance data to the mobile nodes for multi-access

 S. Das & G. Bajko          Expires 01/11/10                  [Page 2]

 ANDSF DHCP Options                                        July 2009

   network scenarios where 3GPP access-network level solutions are not
   sufficient for the mobile nodes to perform network discovery and
   selection of non-3GPP networks[3GPPTS23.402].

   The information provided by ANDSF contains inter-system mobility
   policies and access network specific data to assist the mobile
   node with performing the inter-system handover. This set of
   information can either be provisioned in the mobile node by the
   home operator, or provided to the mobile node (MN) by the ANDSF
   over the S14 reference point as defined in [3GPPTS23.402].

   In 3GPP release-8, the ANDSF is located in the subscriber's home
   operator network and needs to be known to the MN or discovered by
   the MN. According to [3GPPTS23.402] the ANDSF is discovered through
   interaction with the Domain Name Service function or the DHCP Server
   function.

   This document defines new DHCPv4 and DHCPv6 options called the ANDSF
   IP Address Option and ANDSF Domain List Option, which allow the MN to
   locate an ANDSF Server that hosts the desired service as required
   by 3GPP.



2. ANDSF IPv4 Address Option for DHCPv4

   This section describes the ANDSF IPv4 Address Option for DHCPv4.
   The Option begins with an option code followed by a length and one
   or more IP addresses. The value of the length octet does not
   include itself or the option code. The option layout is depicted
   below:

     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   |    Length     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     IP Address                                |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


         Option Code

                OPTION-IPv4_Address-ANDSF(To Be Assigned) - 1 byte

         Length

                An 8-bit field indicating the length of the option
                excluding the 'Option Code' and the 'Length' fields


S. Das & G. Bajko          Expires 01/11/10                  [Page 3]

ANDSF DHCP Options                                        July 2009

   IP Address

                IPv4 address(es) of ANDSF Server(s)

   When the total length of an ANDSF IPv4 Address Option exceeds 254
   octets, the procedure outlined in [RFC3396] MUST be employed to
   split the option into multiple, smaller options.

   If the length is followed by a list of IPv4 addresses indicating
   appropriate ANDSF servers available to the MN, servers MUST be
   listed in order of preference and the client should process them
   in decreasing order of preference. In case there is no ANDSF server
   available, the length is set to 0, otherwise it is a multiple of 4.
   The Option has the following format:

           Code Len    IPv4 Address 1    IPv4 Address 2
         +-----+----+----+----+----+----+----+----+----
         | XX  | n  |a1 | a2  | a3 | a4 | a1 | ...
         +-----+----+----+----+----+----+----+----+----


3. ANDSF Domain Name List Option for DHCPv4

   This section describes the ANDSF Domain Name List Option for DHCPv4.
   The general format of this option is depicted below:

     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   |    Length     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Domain Name List                          |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Option Code

                OPTION-IPv4_FQDN-ANDSF (To Be Assigned) - 1 byte

     Length
                An 8-bit field indicating the length of the option
                excluding the 'Option Code' and the 'Length' fields

      Domain Name List

                FQDN(s) of ANDSF Server

   When the total length of an ANDSF Domain Name List Option exceeds
   254 octets, the procedure outlined in [RFC3396] MUST be employed
   to split the option into multiple, smaller options.


   S. Das & G. Bajko          Expires 01/11/10                [Page 4]

   ANDSF DHCP Options                                      July 2009


  The encoding for this option has the following format:

           Code  Len   DNS name of ANDSF server
         +-----+----+----+----+----+----+----+----
         | XX  | n  | s1 | s2 | s3 | s4 | s5 | ...
         +-----+----+----+----+----+----+----+----

   The Option begins with a code followed by a length and a sequence
   of labels that are encoded according to Section 8 of [RFC3315].

   When the MN discovers one or more FQDNs, it SHALL resolve those
   according to the procedures as specified in [RFC1035]. The list of
   domains MAY contain the domain name of the ANDSF servers of the
   network provider and its partner networks that also offer ANDSF
   capabilities.

   As an example, consider the case where the server wants to offer
   two ANDSF servers, "example.com" and "example.net".  These would
   be encoded as follows:
   +-----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   | XX  |26 | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'c'|'o'|'m'| 0 |
   +-----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   +---+---+---+---+---+---+---+---+---+---+---+---+---+
   | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'n'|'e'|'t'| 0 |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+


4. ANDSF IPv6 Address option for DHCPv6

   This section describes the ANDSF IPv6 Address Option for DHCPv6.
   The Option begins with an option code followed by a length
   and one or more IP addresses. The value of the length octet does
   not include itself or the option code. The option layout is
   depicted below:

     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             |           Length              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     IP Address                                |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option Code

             OPTION-IPv6_Address-ANDSF (To Be Assigned) - 2 bytes



S. Das & G. Bajko          Expires 01/11/10                  [Page 5]

 ANDSF DHCP Options                                        July 2009


   Length

             A 16-bit field indicating the length of the option
             excluding the 'Option Code' and the 'Length' fields.

   IP Address

             IPv6 address(es) of ANDSF Server(s)

   The Option follows the same format (except the Option Code and
   Length value) as described in Section 2. The value of the Option
   Code and Length are 2-octets and the Length does not include
   itself or the Option Code field.

   If the length is followed by a list of IPv6 addresses indicating
   appropriate ANDSF servers available to the MN, servers MUST be
   listed in order of preference and the client should process them in
   decreasing order of preference. In case there is no ANDSF server
   available, the length is set to 0, otherwise it is a multiple of 16.



5. ANDSF Domain Name List option for DHCPv6

   This section describes the ANDSF Domain List Option for DHCPv6. The
   general format of this option is depicted below:

      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             |           Length              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Domain Name List                          |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Option Code

             OPTION-IPv6_FQDN-ANDSF(To Be Assigned) - 2 bytes

       Length

             A 16-bit field indicating the length of the option
             excluding the 'Option Code' and the 'Length' fields.

       Domain Name List

             FQDN(s) of ANDSF Server



   S. Das & G. Bajko          Expires 01/11/10              [Page 6]

   ANDSF DHCP Options                                      July 2009

   The Option follows the same format (except the Option Code and
   Length value) as described in Section 3. The value of the Option
   Code and Length are 2-octets and the Length does not include
   itself or the Option Code field.

   The semantics and content of the DHCPv6 encoding of this option are
   exactly the same as the encoding described in Section 3, except the
   Option Code and Length value.



6. Option Usage

6.1 Usage of ANDSF Options for DHCPv4

   The requesting and sending of the proposed DHCPv4 options follow the
   rules for DHCP options in [RFC2131].

6.1.1 Mobile Node behavior

   The mobile node may perform an ANDSF discovery procedure either
   during initial association with a network or when the policy and
   access network information is required from ANDSF. It may also try to
   perform the ANDSF discovery when the network information is outdated
   or mobile does not have any ANDSF information. MN SHOULD always query
   for the IP address, unless the operator policy requires to discover
   the FQDN, in which case the MN will need to request for the domain
   name.

   In order to request an address or domain name of a ANDSF Server, the
   mobile node(DHCP client) MUST include either an ANDSF IPv4 Address
   Option or ANDSF Domain Name List Option for DHCPv4 in the respective
   DHCP messages as defined in [RFC2131].


6.1.2 DHCP Server behavior

   When the DHCP server receives either an ANDSF IPv4 Address Option or
   ANDSF Domain Name List Option for DHCPv4, the DHCP server MUST always
   construct the response messages (as defined in [RFC2131]) that may
   contain a list of one or more IP addresses or a list of one or more
   FQDNs of the ANDSF server hosting the service.

   In case that the server cannot find any ANDSF Server satisfying
   the requested Option Code, the server MUST return the ANDSF Option
   by setting the Option Code to the requested Option Code and the
   length of the Option to 0.
.



    S. Das & G. Bajko          Expires 01/11/10              [Page 7]

  ANDSF DHCP Options                                       July 2009

6.2 Usage of ANDSF Options for DHCPv6

   The requesting and sending of the proposed DHCPv6 options follow
   the rules for DHCP options in [RFC3315].

  6.2.1 Mobile node behavior

   The mobile node may perform an ANDSF discovery procedure
   either during initial association with a network or when the policy
   and access network information is required from ANDSF. It may also
   try to perform the ANDSF discovery when the network information is
   outdated or mobile does not have any ANDSF information. MN SHOULD
   always query for the IP address, unless the operator policy requires
   to discover the FQDN, in which case the MN will need to request for
   the domain name.

   In order to discover the address or domain name of an ANDSF Server,
   the mobile node(DHCP client) MUST include either an ANDSF IPv6
   Address Option or ANDSF Domain Name List Option for DHCPv6 in the
   respective DHCP messages as defined in [RFC3315].


6.2.2 DHCP Server behavior

   When the DHCP Server receives either an ANDSF IPv6 Address Option
   or ANDSF Domain Name List Option, the DHCP server MUST always
   construct the response (as defined in [RFC3315])that may contain
   a list of one or more IP addresses or a list of one or more FQDNs
   of the ANDSF server hosting the service.

   In case that the server cannot find any ANDSF Server satisfying
   the requested Option Code, the server MUST return the ANDSF Option
   by setting the Option Code to the requested Option Code and the
   length of the Option to 0.



7. Security Considerations

   The security considerations in [RFC2131] apply. If an adversary
   manages to modify the response from a DHCP server or insert its own
   response, an MN could be led to contact a rogue ANDSF Server.

   It is recommended to use DHCP authentication option described in
   [RFC3118] where available. This will also protect the denial of
   service attacks to DHCP servers. [RFC3118] provides mechanisms for
   both entity authentication and message authentication.




S. Das & G. Bajko          Expires 01/11/10                  [Page 8]

ANDSF DHCP Options                                          July 2009

   In deployments where DHCP authentication is not available, 3GPP
   specific lower layer security services may be sufficient to protect
   DHCP messages.

   Regarding domain name resolution, it is recommended to consider the
   usage of DNSSEC [RFC4033] and the aspects of DNSSEC Operational
   Practices [RFC4641].


8. IANA Considerations

   This document defines two new DHCPv4 options as described in Sections
   2 and 3.

   ANDSF IPv4 Address Option for DHCPv4(OPTION-IPv4_Address-ANDSF) TBA

   ANDSF Domain Name List option for DHCPv4(OPTION-IPv4_FQDN-ANDSF) TBA


  This document also defines two DHCPv6 options as described in Sections
  4 and 5.


  ANDSF IPv6 Address Option for DHCPv6 (OPTION-IPv6_Address-ANDSF) TBA

  ANDSF Domain Name List option for DHCPv6 (OPTION-IPv6_FQDN-ANDSF) TBA



9. Acknowledgements

   Authors would like to acknowledge the following individuals for
   their valuable comments.

   Patrick Stuper, Vijay Devarapalli, Jari Arkko,



10. References

    10.1 Normative References

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

   [RFC3315] Dynamic Host Configuration Protocol for IPv6 (DHCPv6),
      Droms et al, July 2003




S. Das & G. Bajko          Expires 01/11/10                 [Page 9]

ANDSF DHCP Options                                        July 2009

   [RFC1035] Mockapetris, P., "Domain names - implementation and
      specification", STD 13, RFC 1035, November 1987.

   [RFC3118] Authentication for DHCP Messages, Droms et al, June 2001


   [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long DHCP Options",
      RFC3396, November 2002.

   [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
       Rose, "DNS Security Introduction and Requirements", RFC 4033,
       March 2005.


   10.2 Informative References


   [RFC4641] Kolkman, O. and R. Gieben, "DNSSEC Operational Practices",
             RFC 4641, September 2006.

   [3GPP TS23.402] www.3gpp.org/ftp/Specs/html-info/23402.htm
                   3GPP TS 23.402 V8.6.0 (2009-06): Architecture
                    enhancements for non-3GPP accesses (Release 8)

   [3GPP Ts 24.302] www.3gpp.org/ftp/Specs/html-info/24302.htm
                    3GPP TS 24.302 V8.2.0 (2009-06): Access to the 3GPP
                    Evolved Packet Core (EPC) via non-3GPP access
                    networks; Stage 3;(Release 8)


Authors' Addresses

   Subir Das
   Telcordia Technologies Inc.
   e-mail: subir(at)research(dot)Telcordia(dot)com

   Gabor Bajko
   Nokia
   e-mail: gabor(dot)bajko(at)nokia(dot)com













S. Das & G. Bajko          Expires 01/11/10                [Page 10]


Html markup produced by rfcmarkup 1.108, available from http://tools.ietf.org/tools/rfcmarkup/