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EAP Attributes for Wi-Fi - EPC Integration
draft-ietf-netext-wifi-epc-eap-attributes-11

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7458.
Authors Ravi Valmikam, Rajeev Koodli
Last updated 2014-08-07 (Latest revision 2014-08-06)
RFC stream Internet Engineering Task Force (IETF)
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Document shepherd Basavaraj Patil
Shepherd write-up Show Last changed 2014-07-28
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Needs a YES.
Responsible AD Brian Haberman
Send notices to netext-chairs@tools.ietf.org, draft-ietf-netext-wifi-epc-eap-attributes@tools.ietf.org
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draft-ietf-netext-wifi-epc-eap-attributes-11
Netext                                                    Ravi. Valmikam
Internet-Draft                                              Unaffiliated
Intended status: Informational                            Rajeev. Koodli
Expires: February 7, 2015                                          Intel
                                                          August 6, 2014

               EAP Attributes for Wi-Fi - EPC Integration
              draft-ietf-netext-wifi-epc-eap-attributes-11

Abstract

   With Wi-Fi emerging as a trusted access network for 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 trusted Wi-Fi
   networks.  This document defines a few new EAP attributes to enable
   the above-mentioned functions in trusted Wi-Fi access networks.

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 February 7, 2015.

Copyright Notice

   Copyright (c) 2014 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

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   (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 . . . . . . . . . . . . . . . .   3
     1.3.  Wi-Fi to E-UTRAN mobility . . . . . . . . . . . . . . . .   4
   2.  Reference Architecture and 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  . . . . . . . . . . . . . . . . .  10
     5.5.  AT_HANDOVER_SESSION_ID  . . . . . . . . . . . . . . . . .  11
     5.6.  AT_MN_SERIAL_ID . . . . . . . . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Wi-Fi has emerged as a trusted access technology for mobile service
   providers.  It has 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 network nodes to undertake the relevant mobility

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   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) can act 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 trusted 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

   Since the attributes defined here 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 [EPC].

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
   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.

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

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   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.

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.  Reference Architecture and 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:

   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

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   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 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  WAP: Wi-Fi Access Point

   o  WAC: Wi-Fi Access Controller.  In a PMIPv6 [RFC5213] network,
      hosts the MAG functionality or is assumed to have a suitable
      interface to the MAG.  In the following, we simply use "WAC"
      notation.  The MAG functionality within the WAC (or within the Wi-
      Fi access network), or a suitable interface to the MAG is assumed
      for PMIPv6 deployments.

   o  IPCN: IP Core Network.  This includes the LMA function.  It
      generically also includes the AAA server function.

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 MN                        WAP                        WAC          IPCN
                                                     (MAG)         (LMA)
 1)|<----------Beacon--------|                         |             |
 2)|<----------Probe-------->|                         |             |
   |                         |                         |             |
   |              802.11 Auth| (Open System)           |             |
 3)|<----------------------->|<----------------------->|             |
   |                         |                         |             |
   |                  802.11 | Association             |             |
 4)|<----------------------->|<----------------------->|             |
   |                         |                         |             |
   |           (802.1X)      |        (CAPWAP/802.1X)  |             |
 5)|<----EAP Req/Identity----|<----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 ====>|<=== CAPWAP(802.3 Data)=>|<=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).  Other formats
   may be defined in the future.

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.

      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

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   Virtual Network Id:

   An arbitrary octet string that identifies a virtual network in the
   access technology 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 value field 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

   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

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   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

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

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   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.

   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

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   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).  Other formats
   may be defined in the future.

   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_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.  New values may
   be defined in the future.

   o  TBA IANA: Reserved

   o  TBA IANA: IMEI

   o  TBA IANA: IMEISV

   MN Serial Id

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   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.

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.  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
   trusted 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).  The same model
   is followed here with the EAP-AKA (or EAP-AKA', EAP-SIM)
   authentication; the AT_VIRTUAL_NETWORK_ID, AT_HANDOVER_INDICATION,
   AT_HANDOVER_SESSION_ID, AT_MN_SERIAL-ID attributes MUST be processed
   only after a successful EAP authentication.  In doing so, these
   attribute processing, security-wise, is no worse than that in
   existing 3G and 4G mobile networks.

   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 for the AT_CONNECTIVITY_TYPE and AT_VIRTUAL_NETWORK_REQ
   attributes defined in this document.

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

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   This document requests a new IANA registry "Trusted non-3GPP Access
   EAP Parameters".  The range for both Types and Sub types in the
   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.  A
   specification would be required to request assignments from this
   registry; see [RFC5226].

   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>.

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>.

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

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   [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.

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

   [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.

   [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.

   [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>.

Appendix A.  Change Log

      o: Initial Draft

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      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

      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

Authors' Addresses

   Ravi Valmikam
   Unaffiliated
   USA

   Email: valmikam@gmail.com

   Rajeev Koodli
   Intel
   USA

   Email: rajeev.koodli@intel.com

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