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Netext                                                    Ravi. Valmikam
Internet-Draft                                              Unaffiliated
Intended status: Informational                            Rajeev. Koodli
Expires: July 9, 2015                                              Intel
                                                         January 5, 2015


               EAP Attributes for Wi-Fi - EPC Integration
              draft-ietf-netext-wifi-epc-eap-attributes-16

Abstract

   With Wi-Fi emerging as a crucial access network for mobile service
   providers, it has become important to provide functions commonly
   available in 3G and 4G networks in Wi-Fi access networks as well.
   Such functions include Access Point Name (APN) Selection, multiple
   Packet Data Network (PDN) connections, and seamless mobility between
   Wi-Fi and 3G/4G networks.

   The EAP-AKA (and EAP-AKA') protocol is required for mobile devices to
   access the mobile Evolved Packet Core (EPC) via Wi-Fi networks.  This
   document defines a few new EAP attributes to enable the above-
   mentioned functions in such networks.  The attributes are exchanged
   between a client (such as a Mobile Node) and its network counterpart
   (such as a AAA server) in the service provider's infrastructure.

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 July 9, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  APN Selection . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Multiple APN Connectivity . . . . . . . . . . . . . . . .   4
     1.3.  Wi-Fi to E-UTRAN mobility . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Brief Introduction to EAP . . . . . . . . . . . . . . . .   4
     3.2.  IEEE 802.11 Authentication using EAP over 802.1X  . . . .   5
   4.  New EAP Attributes  . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  APN Selection . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Connectivity Type . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Wi-Fi to UTRAN/E-UTRAN Mobility . . . . . . . . . . . . .   7
     4.4.  MN Serial ID  . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Attribute Extensions  . . . . . . . . . . . . . . . . . . . .   8
     5.1.  AT_VIRTUAL_NETWORK_ID . . . . . . . . . . . . . . . . . .   8
     5.2.  AT_VIRTUAL_NETWORK_REQ  . . . . . . . . . . . . . . . . .   9
     5.3.  AT_CONNECTIVITY_TYPE  . . . . . . . . . . . . . . . . . .  10
     5.4.  AT_HANDOVER_INDICATION  . . . . . . . . . . . . . . . . .  11
     5.5.  AT_HANDOVER_SESSION_ID  . . . . . . . . . . . . . . . . .  11
     5.6.  AT_MN_SERIAL_ID . . . . . . . . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . .  15
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   Wi-Fi has emerged as a "trusted" access technology for mobile service
   providers; see [EPC2] for reference to the 3GPP description of
   "trusted" access.  Advances in IEEE 802.11u [IEEE802.11u] and
   "HotSpot 2.0" [hs20] have enabled seamless roaming, in which a Mobile
   Node can select and connect to a Wi-Fi access network just as it



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   would roam into a cellular network.  It has thus become important to
   provide certain functions in Wi-Fi which are commonly supported in
   licensed-spectrum networks such as 3G and 4G networks.  This draft
   specifies a few new EAP attributes for a Mobile Node (MN) to interact
   with the network to support some of these functions (see below).
   These new attributes serve as a trigger for Proxy Mobile IPv6 network
   nodes to undertake the relevant mobility operations.  For instance,
   when the Mobile Node requests and the network agrees for a new IP
   session (i.e., a new Access Point Name or APN in 3GPP), the
   corresponding attribute (defined below) acts as a trigger for the
   Mobile Anchor Gateway (MAG) to initiate a new mobility session with
   the Local Mobility Anchor (LMA).  This document refers to [RFC6459]
   for the basic definitions of mobile network terminology (such as APN)
   used here.

   The 3rd Generation Partnership Project (3GPP) networks support many
   functions that are not commonly implemented in a Wi-Fi network.  This
   document defines EAP attributes that enable the following functions
   in Wi-Fi access networks using EAP-AKA' [RFC5448] and EAP-AKA
   [RFC4187]:

      o APN Selection

      o Multiple APN Connectivity

      o Wi-Fi to 3G/4G (UTRAN/EUTRAN) mobility

   The attributes defined here are exchanged between the Mobile Node and
   the EAP server, typically realized as part of the AAA server
   infrastructure in a service provider's infrastructure.  In
   particular, the Wi-Fi access network simply conveys the attributes to
   the service provider's core network where the EAP processing takes
   place [EPC].  Since these attributes share the same IANA registry,
   the methods are applicable to EAP-AKA', EAP-AKA, EAP-SIM [RFC4186]
   and, with appropriate extensions, are possibly applicable for other
   EAP methods as well.  In addition to the trusted Wi-Fi access
   networks, the attributes are applicable to any trusted "non-3GPP"
   access network that uses the EAP methods and provides connectivity to
   the mobile EPC, which provides connectivity for 3G, 4G, and other
   non-3GPP access networks [EPC2].

1.1.  APN Selection

   The 3GPP networks support the concept of an APN (Access Point Name).
   This is defined in [GPRS].  Each APN is an independent IP network
   with its own set of IP services.  When the MN attaches to the
   network, it may select a specific APN to receive desired services.
   For example, to receive generic Internet services, a user device may



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   select APN "Internet" and to receive IMS voice services, it may
   select APN "IMSvoice".

   In a Wi-Fi access scenario, an MN needs a way of sending the desired
   APN name to the network.  This draft specifies a new attribute to
   propagate the APN information via EAP.  The agreed APN is necessary
   for the Proxy Mobile IPv6 MAG to initiate a new session with the LMA.

1.2.  Multiple APN Connectivity

   As an extension of APN Selection, an MN may choose to connect to
   multiple IP networks simultaneously.  3GPP provides this feature via
   additional Packet Data Protocol (PDP) contexts or additional Packet
   Data Network (PDN) connections, and defines the corresponding set of
   signaling procedures.  In a trusted Wi-Fi network, an MN connects to
   the first APN via DHCPv4 or IPv6 Router Solicitation.  This document
   specifies an attribute that indicates the MN's capability to support
   multiple APN connectivity.  The specific connectivity types are also
   necessary for the Proxy Mobile IPv6 signaling.

1.3.  Wi-Fi to E-UTRAN mobility

   When operating in a multi-access network, an MN may want to
   gracefully handover its IP attachment from one access network to
   another.  For instance, an MN connected to a 3GPP E-UTRAN network may
   choose to move its connectivity to a trusted Wi-Fi network.
   Alternatively, the MN may choose to connect using both access
   technologies simultaneously, and maintain two independent IP
   attachments.  To implement these scenarios, the MN needs a way to
   correlate the UTRAN/E-UTRAN session with the new Wi-Fi session.  This
   draft specifies an attribute to propagate E-UTRAN session
   identification to the network via EAP.  This helps the network to
   correlate the sessions between the two Radio Access Network
   technologies and thus helps the overall handover process.

2.  Terminology

   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].

3.  Protocol Overview

3.1.  Brief Introduction to EAP

   EAP is defined as a generic protocol in [RFC3748].  EAP, combined
   with one of the payload protocols such as EAP-AKA' [RFC5448] can
   accomplish several things in a network:



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   o  Establish identity of the user (MN) to the network.

   o  Authenticate the user during the first attach with the help of an
      authentication center that securely maintains the user
      credentials.  This process is called EAP Authentication.

   o  Re-authenticate the user periodically, but without the overhead of
      a round-trip to the authentication center.  This process is called
      EAP Fast Re-Authentication.

   This draft makes use of the EAP Authentication procedure.  The use of
   EAP Fast Re-Authentication procedure is for further study.  Both the
   EAP Authentication and EAP Fast Re-Authentication procedures are
   specified for trusted access network use in 3GPP.  [TS-33.402]

3.2.  IEEE 802.11 Authentication using EAP over 802.1X

   In a Wi-Fi network, EAP is carried over the IEEE 802.1X
   Authentication protocol.  The IEEE 802.1X Authentication is a
   transparent, payload-unaware mechanism to carry the authentication
   messages between the MN and the Wi-Fi network elements.

   EAP, on the other hand, has multiple purposes.  Apart from its core
   functions of communicating an MN's credentials to the network and
   proving the MN's identity, it also allows the MN to send arbitrary
   information elements to help establish the MN's IP session in the
   network.  The following figure shows an example end-to-end EAP flow
   in the context of an IEEE 802.11 Wi-Fi network.  We first define the
   terminology:

   o  MN: Mobile Node

   o  WAN: Wi-Fi Access Node, typically consisting of Wi-Fi Access Point
      and Wi-Fi Controller.  In a PMIPv6 [RFC5213] network, the MAG
      functionality is located in the WAN, either in the Wi-Fi Access
      Point or in the Wi-Fi Controller.

   o  AAA: The infrastructure node supporting the AAA server with the
      EAP methods (AKA, AKA', EAP-SIM).  The end-points of the EAP
      method are the MN and the AAA server.

   o  IPCN: IP Core Network.  This includes the PMIPv6 LMA function.









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  MN                        WAN                        AAA         IPCN
                           (MAG)                                   (LMA)
  1)|<----------Beacon--------|                         |             |
  2)|<----------Probe-------->|                         |             |
    |                         |                         |             |
    |              802.11 Auth|                         |             |
  3)|<----------------------->|                         |             |
    |                         |                         |             |
    |       802.11 Association|                         |             |
  4)|<----------------------->|                         |             |
    |                         |                         |             |
  5)|<----EAP Req/Identity----|                         |             |
    |                         |                         |             |
  6)|----EAP Resp/Identity----|->--EAP Resp/Identity--->|             |
    |                         |                         |             |
  7)|<-EAP Req/AKA-Challenge<-|--EAP Req/AKA-Challenge--|             |
    |                         |                         |             |
  8)|-EAP Resp/AKA-Challenge--|>EAP Resp/AKA-Challenge->|             |
    |                         |                         |             |
  9)|<-----EAP Success------<-|------EAP Success--------|             |
    |                         |                         |             |
 10)|<====== 802.11 Data ====>|<=========== 802.11Data ====Tunnel to=>|
    |                         |                         | core network|
    |                         |                         |             |

                     Figure 1: Example EAP Deployment

   The figure shows separate Wi-Fi Access Point and Wi-Fi Access
   Controller, following the split-MAC model of CAPWAP [RFC5415].  A
   particular deployment may have the two functions within a single
   node.

   1.   An MN detects a beacon from a WAP in the vicinity.

   2.   The MN probes the WAP to determine suitability to attach (Verify
        SSID list, authentication type and so on).

   3.   The MN initiates the IEEE 802.11 Authentication with the Wi-Fi
        network.  In WPA/WPA2 mode, this is an open authentication
        without any security credential verification.

   4.   The MN initiates 802.11 Association with the Wi-Fi network.

   5.   The Wi-Fi network initiates 802.1X/EAP Authentication procedures
        by sending EAP Request/Identity.

   6.   The MN responds with its permanent or temporary identity.




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   7.   The Wi-Fi network challenges the MN to prove its identity by
        sending EAP Request/AKA-Challenge.

   8.   The MN calculates the security digest and responds with EAP
        Response/AKA-Challenge.

   9.   If the authentication is successful, the Wi-Fi network responds
        to the MN with EAP Success.

   10.  An end-to-End data path is available for the MN to start IP
        layer communication (DHCPv4, IPv6 Router Solicitation and so
        on).

4.  New EAP Attributes

   The following sections define the new EAP attributes and their usage.

4.1.  APN Selection

   In a Wi-Fi network, an MN includes the AT_VIRTUAL_NETWORK_ID
   attribute in the EAP-Response/AKA-Challenge to indicate the desired
   APN identity for the first PDN connection.

   If the MN does not include the AT_VIRTUAL_NETWORK_ID attribute in the
   EAP-Response/AKA-Challenge, the network may select an APN by other
   means.  This selection mechanism is outside the scope of this
   document.

   An MN includes the AT_VIRTUAL_NETWORK_REQ attribute to indicate
   single or multiple PDN capability.  In addition, a sub-type in the
   attribute indicates IPv4, IPv6, or dual IPv4v6 PDN connectivity.

4.2.  Connectivity Type

   An MN indicates its preference for connectivity using the
   AT_CONNECTIVITY_TYPE attribute in the EAP-Response/AKA-Challenge
   message.  The preference indicates whether the MN wishes connectivity
   to the Evolved Packet Core (the so-called "EPC PDN connectivity") or
   Internet Offload (termed as "Non-Seamless Wireless Offload").

   The network makes its decision and replies with the same attribute in
   the EAP Success message.

4.3.  Wi-Fi to UTRAN/E-UTRAN Mobility

   When a multi-access MN enters a Wi-Fi network, the following
   parameters are applicable in the EAP-Response/AKA-Challenge for IP
   session continuity from UTRAN/E-UTRAN.



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   o  AT_HANDOVER_INDICATION: This attribute indicates to the network
      that the MN intends to continue the IP session from UTRAN/E-UTRAN.
      If a previous session can be located, network will honor this
      request by connecting the Wi-Fi access to the existing IP session.

   o  AT_HANDOVER_SESSION_ID: An MN MAY use this attribute to identify
      the session on UTRAN/E-UTRAN.  If used, this attribute contains
      P-TMSI (Packet Temporary Mobile Subscriber Identity) if the
      previous session was on UTRAN or M-TMSI (Mobile Temporary Mobile
      Subscriber Identity) if the previous session was on E-UTRAN.  This
      attribute helps the network correlate the Wi-Fi session to an
      existing UTRAN/E-UTRAN session.

4.4.  MN Serial ID

   The MN_SERIAL_ID attribute defines an MN's serial number, including
   International Mobile Equipment Identity (IMEI) and International
   Mobile Equipment Identity Software Version (IMEISV).  The IMEI (or
   IMEISV) is used for ensuring a legitimate (and not a stolen) device
   is in use.  As with the others, this attribute is exchanged with the
   service provider's AAA server.  The MN_SERIAL_ID MUST NOT be
   propagated further by the AAA server to any other node.

5.  Attribute Extensions

   The format for the new attributes follows that in [RFC4187].  Note
   that the Length field value is inclusive of the first two bytes.

5.1.  AT_VIRTUAL_NETWORK_ID

   The AT_VIRTUAL_NETWORK_ID attribute identifies the virtual IP network
   that the MN intends to attach to.  The implementation of the virtual
   network on the core network side is technology specific.  For
   instance, in a 3GPP network, the virtual network is implemented based
   on the 3GPP APN primitive.

   This attribute SHOULD be included in the EAP-Response/AKA-Challenge
   message.













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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |AT_VIRTUAL     | Length        | Virtual Network Id            |
      |  _NETWORK_ID  |               |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Virtual Network Id                           |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 2: AT_VIRTUAL_NETWORK_ID EAP Attribute

   Virtual Network Id:

   An arbitrary octet string that identifies a virtual network in the
   access technology the MN is attaching to.  For instance, in 3GPP
   E-UTRAN, this could be an APN.  See [TS-23.003] for encoding of the
   field.

5.2.  AT_VIRTUAL_NETWORK_REQ

   When an MN intends to connect an APN, it SHOULD use this attribute to
   indicate different capabilities to the network.  In turn, the network
   provides what is supported.

   From the MN, this attribute can be included only in EAP-Response/
   Identity.  From the network, it SHOULD be included in the EAP
   Request/AKA-Challenge message.  In the MN-to-network direction, the
   Type field (below) indicates the MN's request.  In the network-to-MN
   direction, the Type field indicates network's willingness to support
   the request; a present Type field value indicates the network support
   for that Type.

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |AT_VIRTUAL_    |     Length    |  Virt-Net-Req | Virt-Net-Req  |
      |NETWORK_REQ    |               |     Type      |   Sub-type    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 3: AT_VIRTUAL_NETWORK_REQ EAP Attribute

   Virt-Net-Req Type:

   Type can have one of the following values:

   o  TBA IANA: Reserved




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   o  TBA IANA: Single PDN connection

   o  TBA IANA : Multiple PDN connection.  Can request Non-Seamless Wi-
      Fi Offload or EPC connectivity (see the Connectivity Type
      attribute below)

   Virt-Net-Req Sub-type:

   Sub-type can have one of the following values:

   o  TBA IANA : Reserved

   o  TBA IANA : PDN Type: IPv4

   o  TBA IANA : PDN Type: IPv6

   o  TBA IANA : PDN Type: IPv4v6

5.3.  AT_CONNECTIVITY_TYPE

   An MN uses this attribute to indicate whether it wishes the
   connectivity type to be Non-Seamless WLAN Offload or EPC.  This
   attribute is applicable for multiple PDN connections only.

   From the MN, this attribute can be included only in EAP-Response/
   Identity.  From the network, it SHOULD be included in the EAP
   Request/AKA-Challenge message.

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |AT_CONNECTIVITY|     Length    | Connectivity  | Reserved      |
      |_TYPE          |               | Type          |               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 4: AT_CONNECTIVITY_TYPE EAP Attribute

   Connectivity Type:

   Connectivity Type can have one of the following values:

   o  TBA IANA : Reserved

   o  TBA IANA : Non-Seamless WLAN Offload (NSWO)

   o  TBA IANA : EPC PDN connectivity





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5.4.  AT_HANDOVER_INDICATION

   This attribute indicates an MN's handover intention of an existing IP
   attachment.

   This attribute SHOULD be included in the EAP-Response/AKA-Challenge
   message.

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |AT_HANDOVER_IND|     Length    | Handover      |   Pad         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 5: AT_HANDOVER_INDICATION EAP Attribute

   Handover Type:

   o  0 - the MN has no intention of handing over an existing IP
      session, i.e., the MN is requesting an independent IP session with
      the Wi-Fi network without disrupting the IP session with the
      UTRAN/E-UTRAN.  In this case, no Session Id (Section 5.5) is
      included.

   o  1 - the MN intends to handover an existing IP session.  In this
      case, MN MAY include a Session Id (Section 5.5) to correlate this
      Wi-Fi session with a UTRAN/E-UTRAN session.

5.5.  AT_HANDOVER_SESSION_ID

   When an MN intends to handover an earlier IP session to the current
   access network, it may propagate a session identity that can help
   identify the previous session from UTRAN/E-UTRAN that the MN intends
   to handover.  This attribute is defined as a generic octet string.
   The MN MAY include an E-UTRAN GUTI if the previous session was an
   E-UTRAN session.  If the previous session was a UTRAN session, the MN
   MAY include UTRAN Global RNC ID (MCC, MNC, RNC Id) and P-TMSI
   concatenated as an octet string.

   This attribute SHOULD be included in the EAP-Response/AKA-Challenge
   message.










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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |AT_HANDOVER_   |   Length      |  Access       |  Reserved     |
   |  SESSION_ID   |               |  Technology   |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Session Id                          |
   |                              ...                              |
   |                              ...                              |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 6: AT_HANDOVER_SESSION_ID EAP Attribute

   Access Technology:

   This field represents the RAN technology from which the MN is
   undergoing a handover.

   o  TBA IANA: Reserved

   o  TBA IANA: UTRAN

   o  TBA IANA: E-UTRAN

   Session Id:

   An octet string of variable length that identifies the session in the
   source access technology.  As defined at the beginning of this
   section, the actual value is RAN technology dependent.  For E-UTRAN,
   the value is GUTI.  For UTRAN, the value is Global RNC Id (6 bytes)
   followed by P-TMSI (4 bytes).  See [TS-23.003] for encoding of the
   field.

5.6.  AT_MN_SERIAL_ID

   This attribute defines the MN's machine serial number.  Examples are
   International Mobile Equipment Identity (IMEI) and International
   Mobile Equipment Identity Software Version (IMEISV).

   A network that requires the machine serial number for authorization
   purposes MUST send a request for the attribute in an EAP-Request/AKA-
   Challenge message.  If the attribute is present, the MN SHOULD
   include the attribute in the EAP-Response/AKA-Challenge message.  If
   the MN sends the attribute, it MUST be contained within an
   AT_ENCR_DATA attribute.  An MN MUST NOT provide the attribute unless
   it receives the request from a network authenticated via EAP/AKA.




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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |AT_MN_         |   Length      |  Serial ID    |  Reserved     |
   |  SERIAL_ID    |               |    Type       |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           MN Serial Id                        |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 7: AT_MN_SERIAL_ID EAP Attribute

   Serial ID Type:

   This field identifies the type of the MN Identifier.

   o  TBA IANA: Reserved

   o  TBA IANA: IMEI

   o  TBA IANA: IMEISV

   MN Serial Id:

   An arbitrary octet string that identifies the MN's machine serial
   number.  The actual value is device-specific.  See [TS-23.003] for
   encoding of the field.  When sent by the network in the EAP-Request/
   AKA-Challenge message, this field is not present, which serves as an
   indication for the MN to provide the attribute in the EAP-Response/
   AKA-Challenge message.

   AT_MN_SERIAL_ID attribute MUST only be used with methods which can
   provide mutual (network and device) authentication, such as AKA, AKA'
   and EAP-SIM

6.  Security Considerations

   This document defines new EAP attributes to extend the capability of
   the EAP-AKA protocol as specified in Section 8.2 of [RFC4187].  The
   attributes are passed between an MN and a AAA server in provider-
   controlled trusted Wi-Fi networks, where the Wi-Fi Access Network is
   a relay between the MN and the AAA server.  The document does not
   specify any new messages or options to the EAP-AKA protocol.

   The attributes defined here are fields which are used in existing 3G
   and 4G networks, where they are exchanged (in protocols specific to
   3G and 4G networks) subsequent to the mobile network authentication
   (e.g., using the UMTS-AKA mechanism).  For the operator-controled Wi-



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   Fi access which is connected to the same core infrastructure as the
   3G and 4G access, similar model is followed here with the EAP-AKA (or
   EAP-AKA', EAP-SIM) authentication.  In doing so, these attribute
   processing, security-wise, is no worse than that in existing 3G and
   4G mobile networks.

   The attributes inherit the security protection (integrity, replay,
   and confidentiality) provided by the paratmeters in the AKA(') or SIM
   methods ; see Section 12.6 in [RFC4187].  Furthermore, RFC 4187
   requires attributes exchanged in EAP-Request/AKA-Identity or EAP-
   Response/AKA-Identity to be integrity-protected with AT_CHECKCODE;
   see Section 8.2 in [RFC4187].  This requirement applies to the
   AT_CONNECTIVITY_TYPE and AT_VIRTUAL_NETWORK_REQ attributes defined in
   this document.

   The AT_MN_SERIAL_ID attribute MUST have confidentiality protection
   provided by the AKA(') or EAP-SIM methods beyond the secure transport
   (such as private leased lines, VPN etc.) deployed by the provider of
   the trusted Wi-Fi service.

   Use of identifiers such as IMEI could have privacy implications,
   wherein devices can be profiled and tracked.  With additional
   information, this could also lead to profiling of user's network
   access patterns.  Implementers should consult [hotos-2011] and
   references therein for a broader discussion and possible mitigation
   methods on the subject.

7.  IANA Considerations

   This document defines the following new skippable EAP-AKA attributes.
   These attributes need assignments from the "EAP-AKA and EAP-SIM
   Parameters" registry at https://www.iana.org/assignments/eapsimaka-
   numbers

   o  AT_VIRTUAL_NETWORK_ID (Section 5.1) - TBA by IANA

   o  AT_VIRTUAL_NETWORK_REQ (Section 5.2) - TBA by IANA

   o  AT_CONNECTIVITY_TYPE (Section 5.3) - TBA IANA

   o  AT_HANDOVER_INDICATION (Section 5.4) - TBA by IANA

   o  AT_HANDOVER_SESSION_ID (Section 5.5) - TBA by IANA

   o  AT_MN_SERIAL_ID (Section 5.6) - TBA by IANA

   This document requests a new IANA registry "Trusted non-3GPP Access
   EAP Parameters".  The range for both Types and Sub types in the



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   registry is 0 - 127, with 0 (zero) being a reserved value.  The
   document requests IANA to make assignments in a monotonically
   increasing order in increments of 1, starting from 1.  New
   assignments in this registry are made with the Specification Required
   policy [RFC5226].

   The IANA Designated Expert should review the requirements for new
   assignments based on factors including, but not limited to, the
   source of request (e.g., standards bodies), deployment needs (e.g.,
   industry consortium, operator community) and experimental needs
   (e.g., academia, industrial labs).  A document outlining the purpose
   of new assignments should accompany the request.  Such a document
   could be a standards document, or a research project description.
   The Designated Expert should consider that there is sufficient
   evidence of potential usage both on the end-points (e.g., Mobile
   Devices etc.) and the infrastructure (e.g., AAA servers, gateways
   etc.)

   The document requests assignments from the new registry for the
   following fields defined in this document:

   o  Virt-Net-Req Type (Section 5.2) - TBA by IANA

   o  Virt-Net-Req Sub type (Section 5.2) - TBA by IANA

   o  Connectivity Type (Section 5.3) - TBA IANA

   o  Access Technology (Section 5.5) - TBA by IANA

   o  Serial ID Type (Section 5.6) - TBA by IANA

8.  Acknowledgment

   Thanks to Sebastian Speicher for the review and suggesting
   improvements.  Thanks to Mark Grayson for proposing the MN Serial ID
   attribute.  And, thanks to Brian Haberman for suggesting a new
   registry.

9.  References

9.1.  Normative References

   [RFC4187]  Arkko, J. and H. Haverinen, "Extensible Authentication
              Protocol Method for 3rd Generation Authentication and Key
              Agreement (EAP-AKA)", RFC4187, January 2006,
              <http://tools.ietf.org/html/rfc4187>.





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   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6459]  Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
              Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, January 2012.

9.2.  Informative References

   [EPC]      "General Packet Radio Service (GPRS); enhancements for
              Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access, 3GPP TS 23.401 8.8.0, December 2009.",
              <http://www.3gpp.org/ftp/Specs/html-info/23401.htm>.

   [EPC2]     "Architecture enhancements for non-3GPP accesses, 3GPP TS
              23.402 8.8.0, December 2009.",
              <http://www.3gpp.org/ftp/Specs/html-info/23402.htm>.

   [GPRS]     "General Packet Radio Service (GPRS); Service description,
              Stage 2, 3GPP TS 23.060, December 2006",
              <http://www.3gpp.org/ftp/Specs/html-info/23060.htm>.

   [IEEE802.11u]
              "802.11u-2011 - IEEE Standard for Information Technology-
              Telecommunications and information exchange between
              systems- Local and Metropolitan networks-specific
              requirements- Part II: Wireless LAN Medium Access Control
              (MAC) and Physical Layer (PHY) specifications: Amendment
              9: Interworking with External Networks", , Feb 2011,
              <http://standards.ieee.org/findstds/
              standard/802.11u-2011.html>.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, Ed., "Extensible Authentication Protocol
              (EAP)", RFC3748, June 2004,
              <http://www.ietf.org/rfc/rfc3748.txt>.

   [RFC4186]  Haverinen, H. and J. Salowey, "Extensible Authentication
              Protocol Method for Global System for Mobile
              Communications (GSM) Subscriber Identity Modules (EAP-
              SIM)", RFC 4186, January 2006.

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.





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   [RFC5415]  Calhoun, P., Montemurro, M., and D. Stanley, "Control And
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Specification", RFC5415, January 2009,
              <http://www.ietf.org/rfc/rfc5415.txt>.

   [RFC5448]  Arkko, J., Lehtovirta, V., and P. Eronen, "Improved
              Extensible Authentication Protocol Method for 3rd
              Generation Authentication and Key Agreement (EAP-AKA')",
              RFC 5448, May 2009.

   [TS-23.003]
              "3rd Generation Partnership Project: Numbering, Addressing
              and Identification, 3GPP TS 23.003 12.2.0, March 2014.", ,
              <http://www.3gpp.org/ftp/Specs/html-info/23003.htm>.

   [TS-33.402]
              "3GPP System Architecture Evolution (SAE); Security
              aspects of non-3GPP accesses, 3GPP TS 33.402 8.6.0,
              December 2009.", ,
              <http://www.3gpp.org/ftp/Specs/html-info/33402.htm>.

   [hotos-2011]
              D. Wetherall et al., , "Privacy Revelations for Web and
              Mobile Apps.", Proceedings of the Hot Topics in Operating
              Systems (HotOS) , May 2011,
              <https://www.usenix.org/legacy/events/hotos11/tech/>.

   [hs20]     "Hotspot 2.0 (Release 2) Technical Specification Package
              v1.0.0", , <https://www.wi-fi.org/hotspot-20-release-2-
              technical-specification-package-v100>.

Appendix A.  Change Log

      o: Initial Draft

      o: v01: status to Informational, Updated References, Revised the
      Figure

      o: No changes from 01 to 02

      o: Per recent 3GPP updates, added the Connectivity Type attribute
      to allow indicating Non-Seamless WLAN Offload or EPC connectivity

      o: version-04: Revised AT_VIRTUAL_NETWORK_REQ to include 1) single
      PDN vs Multiple PDN connections, 2) PDN Types, and referred to
      NSWO Connectivity Type attribute





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      o: version 05: Added AT_MN_SERIAL_ID.  Revised the IANA
      Considerations section

      o: version 06, 07: various edits

      o: AD review revs

      o: version 09: IETF LC, Directorate review revs

      o: IANA Section revision, based on IANA interaction

      o: version 12 - clarified/revised: 1) IMEI purpose, 2) attributes
      requirement in PMIP6 signaling, 3) references to 802.11u, HotSpot
      2.0 (seamless roaming) 4) References (normative/informative), 5)
      editorial corrections

      o: version 13 - revised AT_MN_SERIAL_ID processing per IESG
      DISCUSS

      o: version 14 -clarified usage of AT_MN_SERIAL_ID.  Provided
      additional reference to "trusted" Wi-Fi access.

      o: version 15,16: Addressed IESG comments.  Revised Figure.

Authors' Addresses

   Ravi Valmikam
   Unaffiliated
   USA

   Email: valmikam@gmail.com


   Rajeev Koodli
   Intel
   USA

   Email: rajeev.koodli@intel.com













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