Network Working Group                                Tom Hiller (Editor)
INTERNET-DRAFT                                       Lucent Technologies
Category: Informational                                        Pat Walsh
<draft-hiller-cdma2000-aaa-01.txt>                             Ameritech
5 June 2000                                           Xing Chen, Alcatel
                                               Mark Munson, GTE Wireless
                                            Gopal Dommety, Cisco Systems
                 Sanjeevan Sivalingham, Ericsson Wireless Communications
                    Byng-Keun Lim, LG Information & Communications, Ltd.
                                                             Pete McCann
                                                           Hajime Shiino
                                                     Lucent Technologies
                                               Brent Hirschman, Motorola
                                                           Serge Manning
                                                         Nortel Networks
                                                 Ray Hsu, Qualcomm, Inc.
                     Haeng Koo, Samsung Telecommunications America, Inc.
                                                Mark Lipford, Sprint PCS
                                                             Pat Calhoun
                                                  Sun Laboratories, Inc.
                                                              Charles Lo
                                                             Eric Jaques
                                                      Vodaphone Airtouch
                                                             Ed Campbell
                                                             Yingchun Xu
                                                        3Com Corporation
                            Shinich Baba, Toshiba America Research, Inc.
                                         Takahiro Ayaki, DDI Corporation
                                             Takuo Seki, IDO Corporation
                                                    Alan Hameed, Fujitsu

              CDMA2000 Wireless Data Requirements for AAA

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

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

     The list of current Internet-Drafts can be accessed at

     The list of Internet-Draft Shadow Directories can be accessed at


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1.  Copyright Notice

Copyright (C) The Internet Society (2000).  All Rights Reserved.

2.  Abstract

This draft specifies cdma2000 wireless data AAA requirements associated
with third generation wireless architecture that supports roaming among
service providers for traditional PPP and Mobile IP services. The
architecture is designed for use with a cellular network as an access

Sections 3, 4, present a brief high level review of the cdma2000
wireless data architecture. Section 5 presents cdma2000 AAA

3.  Introduction

This draft specifies AAA requirements associated with a third generation
cdma2000 wireless architecture that supports roaming among service
providers for traditional PPP and Mobile IP services.  The architecture
is designed for use with a cellular network as an access medium.

Sections 3 and 4 present a brief, high level review of the cdma2000
wireless  data architecture as an aid to interested AAA WG members.
Section 5 presents cdma2000 AAA requirements, and is self contained
relative to the architecture review.

3.1.  Changes

-01: Fixed problems with section number references.

3.2.  Requirements language

In this document, the key words "MAY", "MUST,  "MUST  NOT",  "optional",
"recommended",  "SHOULD",  and  "SHOULD  NOT",  are to be interpreted as
described in [RFC2119].

Please note that the requirements specified in this document are to be
used in evaluating AAA protocol submissions.  As such, the requirements
language refers to capabilities of these protocols; the protocol
documents will specify whether these features are required, recommended,
or optional.  For example, requiring that a protocol support
confidentiality is NOT the same thing as requiring that all protocol
traffic be encrypted.

A protocol submission is not compliant if it fails to satisfy one or
more of the MUST or MUST NOT requirements for the capabilities that it

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implements.  A protocol submission that satisfies all the MUST, MUST
NOT, SHOULD and SHOULD NOT requirements for its capabilities is said to
be "unconditionally compliant"; one that satisfies all the MUST and MUST
NOT requirements but not all the SHOULD or SHOULD NOT requirements for
its protocols is said to be "conditionally compliant."

3.3.  General Service Requirements

   o Provide service during subscriber visiting between wireless
     networks systems while maintaining a formal customer-service
     provider relation with only one wireless service provider.
   o Support Traditional PPP and Mobile IP services:
      o Support dynamic and static home address assignments for
        Mobile IP
      o Support a Home Agent in the mobile's home wireless network,
        home ISP, or private network.
      o Support IP Security on the Mobile IP tunnel between Foreign
        Agent and Home Agent, in order to avoid the overhead of a
        voluntary tunnel on the radio interface.
   o Provide robust authentication, authorization and accounting
     services (AAA):
      o Provide separation of airlink resource AAA services and data
        resource AAA services.
      o Authenticate and authorize a mobile based on an IMSI and an
        NAI. The architecture allows for a carrier to determine if
        billing is based on the IMSI or the NAI.
      o Support optional AAA broker services between wireless
        carriers and between wireless carriers and other external
        data networks.
      o Allow for distribution of specific Mobile IP security key
        information to support home agent assignment, fast handoff,
        and fast HA-FA authentication assignment during registration.
   o Provide QoS

4.  High Level Architecture

The high level architecture is shown in Figure 1.  The six major
entities that compose the network are the Home Agent, the PDSN, the AAA
Server, the Radio Network, the HLR/VLR, and Mobile Client.

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Visited Access              Home Access
Provider Network           Provider Network
  +--------+                 +--------+
  |        |      SS7        |        |
  |  VLR   |-----------------|  HLR   |
  |        |                 |        |
  +--------+                 +--------+
      |  Visited Access      Broker        Home IP
      |  Provider Network    Network       Network
      |     +--------+      +--------+   +--------+
      |     |        |      |        |   |        |
      |     |  AAA   |------|  AAA   |---|  AAA   |
      |     |        |      |        |   |        |
      |     +--------+      +--------+   +--------+
      |             \                \       |
      |              \                \      |
      |               \                \     |
      |                \                \    |
      |                 \                \   |
  +---------+       +---------+       +---------+
  |         |       |         |       |         |
  |   RN    |-------|  PDSN   |-------|  HA     |
  |         |       |         |       |         |
  +---------+       +---------+       +---------+
      |   Visited Access            Home Network
      |  Provider Network           -Private
Mobile|                             -Visited Provider
  IP  |                             -Home Provider
      |                             -Home ISP
   | Mobile |
   | Node   |

Figure 1: General cdma2000 Wireless IP Architecture

4.1.  PDSN

   o Acts as a Foreign Agent;
   o Establish, maintain, and terminate link layer to the mobile
   o Initiate the authentication, authorization and accounting for the
     mobile client;
   o Optionally, securely tunnel using IP security to the Home Agent;
   o Receives service parameters from AAA for mobile client;

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   o Collect usage data for accounting purposes to be relayed to AAA;
   o Routes packets to external packet data networks or to the HA in
     the case of reverse tunneling;
   o Maps home address and Home Agent address to a unique link layer
     identifier used to communicate with Radio Network.

4.2.  Authentication, Authorization, and Accounting Server

   o Interact with the Foreign Agent and other AAA servers to
     authorize, authenticate and perform accounting for the mobile
   o Provides mechanism to support security association between
     PDSN/FA and HA and between the MN and PDSN/FA;
   o For dynamic Home Agent assignment, dynamically identify an HA and
     assign a MN on that HA, and provide the security association
     between the MN and HA;
   o Provide QoS information to the PDSN;
   o Optionally, assign dynamic home address.

4.3.  Radio Network

   o Maps Mobile Client identifier reference to a unique link layer
     identifier used to communicate with PDSN;
   o Validates Mobile Station for access service;
   o Manages physical layer connection to the Mobile Client;
   o Maintain state of reachability for packet service between the
     access radio network and the mobile station;
   o Buffers packets arriving from the PDSN, when radio resources are
     not in place or are insufficient to support the flow from the
   o Relays packets between the mobile station and the PDSN.

4.4.  Location Registers (VLR/HLR)

   o Stores authentication and authorization information for the radio

4.5.  Home Agent

   o Maintains user registration and redirects packets to the PDSN;
   o Optionally, establish an IP secure tunnel to the PDSN/FA;
   o Supports the dynamic Home Agent assignment;
   o Optionally, assigns dynamic home address;
   o Support reverse tunneling.

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4.6.  Mobile Node

   o Support PPP;
   o Can act as a Mobile IP Node; and support Foreign Agent Challenge
     and NAI;
   o Interacts with the Radio Network to obtain appropriate radio
     resources from the network for the exchange of packets;
   o Maintains knowledge of status of radio resources (e.g., active,
     standby, dormant);
   o Buffers packets when radio resources are not in place or are
     insufficient to support the flow to the network.

5.  AAA Requirements

5.1.  Core AAA Requirements

The following is a summary of cdma2000 AAA specific requirements. In
these requirements, the serving network and home network may or may not
have a direct business relationship. In such cases in which there is not
a direct business relationship, service may be supported indirectly via

   o Authenticate and authorize a user NAI in a roaming environment.
     The NAI is obtained via CHAP (for traditional PPP service) or a
     Foreign Agent Challenge (for Mobile IP service). A shared secret
     exists between the mobile and its HAAA. The FAC will typically be
     computed in a manner  consistent with CHAP.
   o Transport wireless data attributes from the home network to the
     Serving network. This may often take the form of a user profile.
   o Encrypt or sign one or more AVPs in an AAA message between home,
     serving network, or some broker across multiple AAA server hops.
   o Support a reliable AAA transport mechanism.
      o This transport mechanism will be able indicate to an AAA
        application that a message was delivered to the next peer AAA
        application or that a time out occurred.
      o Retransmission is controlled by the reliable AAA transport
        mechanism, and not by lower layer protocols such as TCP.
      o Even if the AAA message is to be forwarded, or the message's
        options or semantics do not conform with the AAA protocol, the
        transport mechanism will acknowledge that the peer received the
        AAA message. However, if the message fails to pass
        authentication, it will not be acknowledged.
      o Acknowledgements should be allowed to be piggybacked in AAA
      o The reliable transport mechanism features shall have the
        capability to detect silent failures of the AAA peer or path to
        the AAA peer, to manage failure on a proactive basis.

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   o Transport a digital certificate in an AAA message, in order to
     minimize the number of round trips associated with AAA
     transactions. Note: This requirement applies to AAA applications
     and not mobile stations.
   o Support both proxy and non-proxy brokers, where non-proxy brokers
     imply the broker terminates an entire request and initiates a new
     request. AAA brokers should have the capability to modify certain
     parts of AAA messages whereby to operate to in non-proxy or proxy
   o Provide message integrity and identity authentication on a per hop
     (AAA node) basis.
   o Support replay protection and optional non-repudiation
     capabilities for all authorization and accounting messages. The
     AAA protocol must provide the capability for accounting messages
     to be matched with prior authorization messages.
   o Support accounting via both bilateral arrangements and via broker
     AAA servers providing accounting clearinghouse and reconciliation
     between serving and home networks. There is an explicit agreement
     that if the private network or home ISP authenticates the mobile
     station requesting service, then the private network or home ISP
     network also agrees to reconcile charges with the home service
     provider or broker.  Real time accounting must be supported.
   o Provides security between AAA servers, and between AAA server and
     PDSN or HA via IP security.

5.2.  Mobile IP Specific Requirements and AAA

5.2.1.  Mobile IP Security Discussion

Three Mobile IP security extensions are defined in RFC 2002:

     . HA - FA
     . MN - FA
     . HA - MN

Therefore, Mobile IP and IPsec security models differ in that Mobile IP
provides its own authentication mechanisms calculated within the Mobile
IP registration procedures whereas IPsec uses IPsec AH.

The keys and SPIs associated with the MN-FA and HA-FA extensions need to
be dynamically established in a roaming wireless carrier environment.
The MN-FA extension is useful for allowing a new FA (PDSN) to quickly
authenticate a mobile using the previous foreign agent extension. The
HA-FA extension is useful for the HA to ensure that only FAs from
carrier's with roaming agreements access the HA.  The MN-HA is usually
provisioned, but for dynamic Home Agent assignment, this security
association must be dynamically created.

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It is possible to use IPsec AH between MN and FA, FA and HA, and MN and
HA. IKE may be used to establish security associations between these
entities. However, use of IKE may pose a problem for smaller mobiles and
may introduce unacceptable delays for certain applications (e.g. Voice
Over IP). The following three sections outline Mobile IP specific
functions that benefit from AAA based key distribution.

5.2.2.  Dynamic Home Agent Assignment

A visited or home AAA server will optionally be able perform dynamic HA
assignment. For dynamically assigned HA, the visited AAA server will
indicate to the home AAA server whether it supports dynamic HA
assignment in those cases in which the mobile node requests dynamic
assignment. If so indicated, the home AAA server may choose to allow the
visited AAA server to perform the HA assignment. Otherwise, the home AAA
assigns the HA.

5.2.3.  Fast Handoff

To achieve a faster handoff, the mobile may attempt to avoid an AAA
transaction with the home AAA server. To accomplish this, the mobile may
send the PDSN the Previous FA address in the RRQ message from the
mobile, along with the MN-FA authentication extension. The new PDSN
passes the Previous FA address and MN-FA authentication extension to the
visited AAA server. If the visited AAA server is able authenticate the
MN-FA authentication extension for the mobile, then the visited AAA may
be able to avoid an actual transaction to the home AAA server.

5.2.4.  HA-FA Authentication

To achieve a fast registration for the case of a mobile station with a
Home Agent, the PDSN and HA may receive from the AAA mechanism a HA-FA
key and SPI that is used to authenticate the PDSN and the HA to each

5.2.5.  Key Distribution

These functions are primarily useful in a wireless environment in which
handoffs may occur rapidly (implying a need for low latency), or where
mobile devices have limited computing power. To achieve these functions,
AAA will be used to securely pass keys and SPIs between the serving
network and target network in encrypted form.  These keys are then used
for the specific functions outlined in this draft.

5.3.  IKE and AAA

The use of IKE in the cdma2000 wireless architecture requires the use of
certificates. However, the AAA servers may be able to distribute a pre-

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shared key to the Mobile IP Agents for use during Phase 1 ISAKMP
exchanges. This may lessen the need for on-line revocation checks.

5.4.  Interoperability with RADIUS

Users with a home AAA server based on RADIUS may desire to roam into a
wireless carrier network that uses "new" AAA servers based on the
requirements in this draft, and vice verse. The AAA protocol should be
designed in a way so as to make conversions to and from RADIUS messages
straight forward. This will allow for the development of gateway
processes to aid in interoperability.  Note: The features of the new AAA
protocols which are beyond the feature set of the RADIUS protocol will
not be available for users while on home or serving networks based on

6.  References

     Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.

7.  Security Considerations

This document is very much about security. These requirements do not
require the serving and home networks to not be in the same domain nor
must they have a direct relationship. The serving network requires
authorization from the home network so that the serving network obtains
proof it will get paid for services rendered to the mobile. This implies
the home network must authenticate the user.  AAA functions must be
performed in a secure manner. The requirements contained in section 3
outline the security required.

Mobile IP supports authentication mechanisms outside IP Security.  These
mechanism may be enhanced in a cellular wireless environment by allowing
a home AAA server to distribute keys to the serving network.
Additionally, the home AAA server may be able to send a pre-shared key
to be used in Phase 1 ISAKMP security association establishment between
FA and HA. These keys would sent in encrypted form from the home network
to the serving network. As supported in the requirements contained in
section 3, the encryption could be handled via public cryptography and

8.  IANA Considerations

This draft does not create any new number spaces for IANA

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9.  Acknowledgements

The authors are active members of the TIA TR45.6 committee.

10.  Authors' Addresses

Pat R. Calhoun
Network and Security Research Center, Sun Labs
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, CA 94025
Phone: (650)-786-7733

Ed Campbell
3Com Corporation
1800 W. Central Rd.
Mount Prospect, IL 60056
Phone: (847) 342-6769

Gopal Dommety
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134

Tom Hiller
Rm 2F-218
263 Shuman Dr.
Lucent Technologies
Naperville, IL
Phone: (630) 979-7673

Raymond T. Hsu
Qualcomm Inc.
6455 Lusk Blvd.
San Diego, CA 92121
Phone: (619) 651-3623

Mark A. Lipford
Sprint PCS
8001 College Blvd.; Suite 210
Overland Park, KS  66210
Phone: (913) 664-8335

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Serge Manning
Nortel Networks
2201 Lakeside Blvd
Richardson, TX  75082-4399
Phone: (972) 684-7277

Peter J. McCann
Lucent Technologies
Rm 2Z-305
263 Shuman Blvd
Naperville, IL  60566
Phone: (630) 713 9359

Mark Munson
GTE Wireless
One GTE Place
Alpharetta, GA  30004
Phone: (678) 339-4439

Haeng Koo
Samsung Telecommunications America, Inc.
1130 E. Arapaho Road
Richardson, TX, USA  75025
Phone: (972) 761-7735

Pat Walsh
2000 W. Ameritech Ctr. Dr.
Hoffman Estates, IL  60195
Phone: (847) 765-5845

Yingchun Xu
3Com Corporation
1800 W. Central Rd.
Mount Prospect, IL 60056
Phone: (847) 342-6814

Brent Hirschman
1501 Shure Dr.
Arlington Hieghts, IL 60006
Phone: (847) 632-1563

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Eric Jaques
Vodafone AirTouch
2999 Oak Road, MS-750
Walnut Creek, CA 94596
Phone: +1-925-279-6142

Sanjeevan Sivalingham
Ericsson Wireless Communications Inc.,
Rm Q-356C
6455 Lusk Blvd
San Diego, CA 92126
Phone: (858) 332-5670

Xing Chen
Alcatel USA
1000 Coit Road
Plano, TX 75075, USA
Phone: 972-519-4142
Fax: 972-519-4843

Byng-Keun Lim,
LG Information & Communications, Ltd.
533, Hogye-dong, Dongan-ku, Anyang-shi, Kyungki-do,431-080,
Phone: +82-343-450-7199
Fax: +82-343-450-7050

Hajime Shiino
Lucent Technologies Japan Ltd.
25 Mori Bldg. 1-4-30 Roppongi,
Minato-ku Tokyo

Shinich Baba
Toshiba America Research, Inc.
PO Box 136,
Convent Station, NJ 07961-0136
Phone: (973) 829-4795

Takahiro Ayaki
DDI corporation
Ichibancho FS Bldg.

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8, Ichibancho, Chiyoda-ku Tokyo
Phone: +81-3-3221-9682

Alan Hameed
2801 Telecom Parkway
Richardson, Texas 75082
Phone: (972) 479-2089

Charles N. Lo
Vodafone AirTouch
2999 Oak Rd

Walnut Creek, CA  94596
Phone: (925) 210-3460

Takuo Seki
IDO Corporation
Gobancho YS Bldg.
12-3, Gobancho, Chiyoda-ku Tokyo
Phone: +81-3-3263-9660

11.  Full Copyright Statement

Copyright (C) The Internet Society (2000).  All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it or
assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are included
on all such copies and derivative works.  However, this document itself
may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations,
except as needed for the purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.  The limited permissions granted above are
perpetual and will not be revoked by the Internet Society or its
successors or assigns.  This document and the information contained
herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE

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12.  Expiration Date

This memo is filed as <draft-hiller-cdma2000-aaa-01.txt>,  and  expires
January 1, 2001.

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