DHCPv4 and DHCPv6 Options for Access Network Discovery and Selection Function (ANDSF) Discovery
draft-das-mipshop-andsf-dhcp-options-07

Internet Engineering Task Force                                Subir Das
Internet-Draft                                    Telcordia Technologies
Intended status: Proposed Standard                           Gabor Bajko 
Expires: April 21, 2011                                            Nokia
                                                        October 19, 2010  
 

Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Options for
Access Network Discovery and Selection Function(ANDSF) Discovery
                    draft-das-mipshop-andsf-dhcp-options-07 

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ANDSF DHCP Options                                       October 2010 
 
Abstract 
    
   This document defines new Dynamic Host Configuration Protocol  
   (DHCPv4 and DHCPv6) options to enable a mobile node to discover
   Access Network Discovery and Selection Function (ANDSF) entities 
   in an IP network. ANDSF is being developed in 3GPP and provides 
   inter-system mobility policies and access network specific 
   information to the mobile nodes(MNs). 
            

   
Table of Contents 
    
   1. Introduction .................................................2 
   2. ANDSF IPv4 address option for DHCPv4..........................3 
   3. ANDSF IPv6 address option for DHCPv6..........................4     
   4. Option Usage..................................................5 
        4.1 Usage of ANDSF Options for DHCPv4.......................5 
        4.2 Usage of ANDSF Options for DHCPv6.......................6 
   5. Security Considerations ......................................6 
   6. IANA Considerations ..........................................6 
   7. Acknowledgements .............................................7 
   8. References ...................................................7 
       8.1 Normative References ....................................7
       8.2 Informative References ..................................7 
   Author's Addresses ..............................................7 

(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 [RFC2119]. 
    
 
(2) Terminology and abbreviations used in this document 
    
   ANDSF (Access Network Discovery and Selection Function): An entity
   that provides 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: A radio access network specified by Third Generation 
   Partnership Project 

   Non-3GPP Network: A radio access network specified outside 3GPP by 
   Other Projects or Standards Organizations.

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1. Introduction 

   Access Network Discovery and Selection Function (ANDSF) is being
   defined in 3GPP [3GPPTS23.402] to provide necessary network 
   discovery and selection assistance data to the mobile nodes for 
   multi-access 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. 

   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) dynamically by 
   the ANDSF over the S14 reference point as defined in [3GPPTS23.402]. 

   In 3GPP, the ANDSF is located either in the subscriber's home 
   operator or visited 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 Options, which allow the MN to locate an ANDSF Server. 
    
 
2. ANDSF IPv4 Address Option for DHCPv4
    
   This section describes the ANDSF IPv4 Address Option for DHCPv4. 
   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) 
    

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ANDSF DHCP Options                                       October 2010 

   Length 
        
             Length (in bytes) of the option excluding the 'Option
             Code' and the 'Length' fields; Length field is set to
             4N, where N is the number of IPv4 addresses carried in
             the option   

   IP Address
    
                IPv4 address(es) of ANDSF Server(s) 

  
   ANDSF servers MUST be listed in order of preference and the client
   SHOULD process them in decreasing order of preference.

           

3. ANDSF IPv6 Address option for DHCPv6 
    
   This section describes the ANDSF IPv6 Address Option for DHCPv6. 
   All values in the option are represented in network byte order. 
   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) 

   
   Length 
             Length (in bytes) of the option excluding the 'Option
             Code' and the 'Length' fields; Length field is set to
             16N, where N is the number of IPv6 addresses carried
             in the option

 
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 IP Address
    
             IPv6 address(es) of ANDSF Server(s) 
   
   
   ANDSF servers MUST be listed in order of preference and the client
   SHOULD process them in decreasing order of preference.
 
                 
4. Option Usage 
    
4.1 Usage of ANDSF Options for DHCPv4 
     
   The requesting and sending of the proposed DHCPv4 options follow 
   the rules for DHCP options in [RFC2131]. 
     
  4.1.1 Mobile Node behavior 
    
   The mobile node MAY request the IP address of an ANDSF server 
   either during initial association with a network or when the 
   policy and access network information is required from ANDSF. It 
   MAY also request the IP address of an ANDSF server when the network 
   information is outdated or mobile does not have any ANDSF 
   information. 
    
   In order to request an address of a ANDSF Server, the mobile node 
   (DHCP client) MUST include an ANDSF IPv4 Address Option in the 
   Parameter Request List(PRL)in the respective DHCP messages as 
   defined in [RFC2131] and [RFC2132]. The DHCP Client MAY initiate a 
   new DHCP exchange or piggyback on other DHCP message exchanges. DHCP 
   client handling PRL options is specified in RFC2131, Section 4.4.

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

    
  4.2.1 Mobile node behavior 
    
   The mobile node MAY request the IP address of an ANDSF server
   according to the scenarios described in Section 4.1.1. 

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ANDSF DHCP Options                                       October 2010

   

   In order to discover the address of an ANDSF Server, the mobile 
   node(DHCP client) MUST include an ANDSF IPv6 Address Option in the 
   Option Request Option (ORO) in the respective DHCP messages as 
   defined in [RFC3315]. The DHCP client MAY initiate a new DHCP 
   exchange or piggyback on other DHCP message exchanges. DHCP 
   client handling ORO options is specified in RFC3315, Sections 17.1 
   and 18.1. 

  
5. Security Considerations 
    
   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. A modified response could also be used to mount an
   amplification attack.
   
   DHCP authentication option described in [RFC3118] and [RFC3315] MAY 
   be used to mitigate the above attacks. In deployments where DHCP 
   authentication is not available, 3GPP specific lower layer security 
   services can be used to protect DHCP messages[3GPPTS33.402]. 3GPP 
   ANDSF framework also provides additional mechanisms that can also be 
   used to mitigate above attacks and to protect message exchanges 
   between ANDSF client and server at the higher layer [3GPPTS33.402]. 
        
   
6. IANA Considerations 

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

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

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

       
7. Acknowledgements 
 
   Authors would like to acknowledge the following individuals for 
   their valuable comments. 
   
   Patrick Stuper, Vijay Devarapalli, Jouni Korhonen, Jari Arkko, 
   Ted Lemon and Ralph Droms

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 8. References

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

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

   [RFC2132] S. Alexander, Droms, R. "DHCP Options and BOOTP Vendor 
      Extensions", RFC 2132, March 1997
 
   [RFC3315] Droms, R.,  et al,  "Dynamic Host Configuration Protocol 
      for IPv6 (DHCPv6)", RFC 3315, July 2003

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

   
   8.2 Informative References 

        
   [3GPPTS23.402] www.3gpp.org/ftp/Specs/html-info/23402.htm
                   3GPP TS 23.402 V8.8.0 (2009-12): Architecture 
                    enhancements for non-3GPP accesses 

   [3GPPTS24.302] www.3gpp.org/ftp/Specs/html-info/24302.htm
                    3GPP TS 24.302 V8.4.1 (2009-12): Access to the 3GPP 
                    Evolved Packet Core (EPC) via non-3GPP access 
                    Networks 

   [3GPPTS33.402]:www.3gpp.org/ftp/Specs/html-info/33402.htm
                    3GPP TS 33.402 v8.6.0 (2009-120) System 
                    Architecture Evolution: Security aspects of 
                    non-3GPP accesses
    

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 

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