Internet DRAFT - draft-lijun-dhc-clf-nass-option

draft-lijun-dhc-clf-nass-option




Internet-Draft                                                    Li Jun
<draft-lijun-dhc-clf-nass-option-01.txt>                          Huawei
Oct 15, 2005                                                          
Expires: April 15,2006                                                


		    DHCP Option for CLF/NASS                           
                draft-lijun-dhc-clf-nass-option-01.txt

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Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document defines a new dhcp option for Access Network 
   Information discovery. The network terminal can get the Access 
   Network Information,which it is attached, through this option. And
   the Access Network Information can be used for different purpose, 
   such as in TISPAN NGN network the Access Network Information can be
   used to discover the CLF(Connectivity Session Location and Repository
   Function) of the NASS (Network Attachment Subsystem).This document 
   defines the related dhcp option and option codes. 
   
  






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1. Introduction 

   In many cases, the Dynamic Host Configuration Protocol (DHCP) as 
   defined in RFC 2131 is used to configure the customer premise host. 
   For example, in TISPAN NGN functional architecture, DHCP is used to 
   configure the TE (NGN terminal),such as DHCP option 120 is used to 
   configure the P-CSCF address [RFC3361]. And also, more DHCP options 
   are needed to carry other configuration parameters, such as access 
   network information, that may contain the Access Network Identifier
   (ANID) or other information of the access network which the the TE 
   attached.But the existing DHCP options do not support carrying the 
   access network information. 
   One of the requirement for the DHCP to carry access network 
   information is as follows. In TISPAM NGN network, the TE need 
   discover the access network identifier and inform the service control
   subsytem which access network it attached to.
   
   The NASS, Network Attachment Subsystem, in ETSI NGN Functional 
   Architecture has the following model [NASS]:

                           +---------------------------+
                           | Service Control Subsystem |
                           |     and Applications      |
                           +---------------------------+                  
                                        |                  
                                        |e2
                                        |                   
                                   +---------+       e4       +--------+   
                                   |   CLF   |----------------|  RACS  |
                                   +---------+                +--------+
                                  /           \
                                 /             \
                                /               \
         +---------+    +---------+           +---------+     +--------+
         |  CPECF  |    |   NACF  |           |   UAAF  |-----|  PDBF  |
         +---------+    +---------+           +---------+     +--------+
                |               \               /
             e3 |                \             /
                |                 \           /
    +----+   +-----+   +-----+     +---------+
    | TE |---| CNG |---| ARF |-----|   AMF   +
    +----+   +-----+   +-----+  e1 +---------+

Definition:
	NACF: Network Access Configuration Function is responsible for 
	the IP address allocation to the TE. It may also distribute 
	other network configuration parameters.DHCP servers are typical
	implementations of the NACF.
	AMF: Access Management Function translates network access 
	requests issued by the TE. It forwards the requests for 
	allocation of an IP address and possibly additional network 
	configuration parameters to/from the NACF.
   
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	CLF: Connectivity Session Location and Repository Function 
	registers the association between the IP address allocated to 
	the TE and related network location information provided by the    
   	NACF. And the CLF responds to location queries from service 
	control subsystems and applications.
	UAAF: User Access Authorization Function performs user 
	authentication, as well as authorisation checking, based on user
	profiles, for network access. 
	PDBF: Profile Data Base Function
	CPECF: CPE Configuration Function
	
   In this architecture, a Service Control Subsystem may serve serveral
   access networks. The Service Control Subsystem need to communicate 
   with the NASS of access network. The contact point of NASS is CLF. So 
   the NACF should be able to provide to the TE an access network 
   identifier. This information uniquely identifies the access network 
   to which the TE is attached. When the TE accesses or registers to the
   Service Control Subsystem,it will carry the access network identifier
   obtained from NACF. With this information the Service Control system 
   should be able to locate the CLF of NASS.

   The transport of the access identifier depends on extension in 
   existing DHCP protocols. This memo is an effort to define the DHCP 
   option to carry the access network information, such as access network
   identifier (ANID) and CLF identifier (CLFID).

2.  Terminology

   The keywords "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.

3.  Access Network Information Option

   This section defines the configuration option for the access network
   information.The new option is organized as a single DHCP option that 
   contains one or more "sub-options".The initial sub-options are
   defined for TISPAN NGN architecture and general purpose. These 
   include a "ANID" sub-option for access network identifier,and a 
   "CLFID" sub-option for TISPAN CLF identifier. The format of the 
   access network information option is:

          Code   Len     Access network Information Field
         +------+------+------+------+------+------+--...-+------+
         | TBD  |   N  |  i1  |  i2  |  i3  |  i4  |      |  iN  |
         +------+------+------+------+------+------+--...-+------+

   The length N gives the total number of octets in the Access Network
   Information Field.  The Access Network Information field consists of 
   a sequence of SubOpt/Length/Value tuples for each sub-option, encoded
   in the following manner:



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          SubOpt  Len     Sub-option Value
         +------+------+------+------+------+------+--...-+------+
         |  1   |   N  |  i1  |  i2  |  i3  |  i4  |      |  iN  |
         +------+------+------+------+------+------+--...-+------+
          SubOpt  Len     Sub-option Value
         +------+------+------+------+------+------+--...-+------+
         |  2   |   N  |  i1  |  i2  |  i3  |  i4  |      |  iN  |
         +------+------+------+------+------+------+--...-+------+
         
   The initial assignment of Access Network Information Sub-options is 
   as follows:
   
      Access Network Information    Sub-Option Description
           Sub-option Code
           ---------------          ----------------------
                1                   Access Network ID Sub-option
                2                   CLF ID Sub-option
   
   Notes: Generally, Access Network Identifier is suffice to indicate 
   the attached access network. But in some case, more infomations of
   the access network may be required by some services or applications.
   So more sub-option need to be defined to carry this informations.
   Such as in TISPAN NGN architecture, the service control subsystem may
   want to get the CLF address from TE directly, so a CLFID sub-option 
   is defined.

3.1 Access Network ID Sub-option

   The ANID sub-option contains a character string indicating the Access
   Network. The ANID sub-option has the following format:
   
          SubOpt   Len     Access Netwok ID
         +------+------+------+------+------+------+------+------+--
         |  1   |   n  |  c1  |  c2  |  c3  |  c4  |  c5  |  c6  | ...
         +------+------+------+------+------+------+------+------+--
      
   An example case when the access network is "China-telecom-001" will 
   be:
       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
       | 1 |17 |'c'|'h'|'i'|'n'|'a'|'-'|'t'|'e'|'l'|'e'|'c'|'o'|'m'|'-'|
       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
       +---+---+---+
       |'0'|'0'|'1'|
       +---+---+---+

       
3.2 CLF ID Sub-option

   The CLFID sub-option contains the CLF indentifier, which may be one or 
   more IPV4 addresss or domain names of the CLF. 
   
   The coding of the CLFID is out of scope the draft. 
   
       
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4.  IANA Considerations

   The option code for this dhcp option MUST be assigned by IANA.



5  Normative References

   [NASS]     Draft ETSI ES 02021 V1.0.0 NGN Functional Architecture,
              Network Attachment Subsystem, Release 1

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

   [RFC3361]  Schulzrinne, "DHCPv4 Option for SIP Servers", RFC 3361, 
              August 2002.
   
   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.


6  Author's Address

   Li Jun
   Huawei Industrial Base
   Bantian Longgang
   Shenzhen 518129 P.R.C 
   EMail:  Leejun@huawei.com  
   Fax: +86-755-28972045
   Phone: +86-13823734043
   
   
7  Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
   
   
8  Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.  


    

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