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rfc:rfc7494

Internet Engineering Task Force (IETF) C. Shao Request for Comments: 7494 H. Deng Category: Standards Track China Mobile ISSN: 2070-1721 R. Pazhyannur

                                                         Cisco Systems
                                                               F. Bari
                                                                  AT&T
                                                              R. Zhang
                                                         China Telecom
                                                         S. Matsushima
                                                      SoftBank Telecom
                                                            April 2015
  IEEE 802.11 Medium Access Control (MAC) Profile for Control and
          Provisioning of Wireless Access Points (CAPWAP)

Abstract

 The Control and Provisioning of Wireless Access Points (CAPWAP)
 protocol binding for IEEE 802.11 defines two Medium Access Control
 (MAC) modes for IEEE 802.11 Wireless Transmission Points (WTPs):
 Split and Local MAC.  In the Split MAC mode, the partitioning of
 encryption/decryption functions is not clearly defined.  In the Split
 MAC mode description, IEEE 802.11 encryption is specified as located
 in either the Access Controller (AC) or the WTP, with no clear way
 for the AC to inform the WTP of where the encryption functionality
 should be located.  This leads to interoperability issues, especially
 when the AC and WTP come from different vendors.  To prevent
 interoperability issues, this specification defines an IEEE 802.11
 MAC Profile message element in which each profile specifies an
 unambiguous division of encryption functionality between the WTP and
 AC.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7494.

Shao, et al. Standards Track [Page 1] RFC 7494 CAPWAP MAC Profile April 2015

Copyright Notice

 Copyright (c) 2015 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
 (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  . . . . . . . . . . . . . . . . . . . . . . . .   3
 2.  IEEE MAC Profile Descriptions . . . . . . . . . . . . . . . .   5
   2.1.  Split MAC with WTP Encryption . . . . . . . . . . . . . .   5
   2.2.  Split MAC with AC Encryption  . . . . . . . . . . . . . .   6
   2.3.  IEEE 802.11 MAC Profile Frame Exchange  . . . . . . . . .   8
 3.  MAC Profile Message Element Definitions . . . . . . . . . . .   8
   3.1.  IEEE 802.11 Supported MAC Profiles  . . . . . . . . . . .   8
   3.2.  IEEE 802.11 MAC Profile . . . . . . . . . . . . . . . . .   9
 4.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
 5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
 6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   6.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
   6.2.  Informative References  . . . . . . . . . . . . . . . . .  11
 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  12
 Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

Shao, et al. Standards Track [Page 2] RFC 7494 CAPWAP MAC Profile April 2015

1. Introduction

 The CAPWAP protocol supports two MAC modes of operation: Split and
 Local MAC, as described in [RFC5415] and [RFC5416].  However, there
 are MAC functions that have not been clearly defined.  For example,
 IEEE 802.11 [IEEE.802.11] encryption is specified as located in
 either the AC or the WTP with no clear way to negotiate where it
 should be located.  Because different vendors have different
 definitions of the MAC mode, many MAC-layer functions are mapped
 differently to either the WTP or the AC by different vendors.
 Therefore, depending upon the vendor, the operators in their
 deployments have to perform different configurations based on
 implementation of the two modes by their vendor.  If there is no
 clear specification, then operators will experience interoperability
 issues with WTPs and ACs from different vendors.
 Figure 1 from [RFC5416] illustrates how some functions are processed
 in different places in the Local MAC and Split MAC mode.
 Specifically, note that in the Split MAC mode, the IEEE 802.11
 encryption/decryption is specified as WTP/AC, implying that it could
 be at either location.  This is not an issue with Local MAC because
 encryption is always at the WTP.

Shao, et al. Standards Track [Page 3] RFC 7494 CAPWAP MAC Profile April 2015

 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Functions                  | Local MAC | Split MAC |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Distribution Service     |  WTP/AC   |     AC    |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Integration Service      |   WTP     |     AC    |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Beacon Generation        |   WTP     |     WTP   |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Probe Response Generation|   WTP     |     WTP   |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Function    |Power Mgmt/              |   WTP     |     WTP   |
 +             |Packet Buffering         |           |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Fragmentation/           |   WTP     |    WTP/AC |
 +             |Defragmentation          |           |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Assoc/Disassoc/Reassoc   |  WTP/AC   |     AC    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Classifying              |   WTP     |     AC    |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 QoS  |Scheduling               |   WTP     |    WTP/AC |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Queuing                  |   WTP     |    WTP    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.1X/EAP          |   AC      |    AC     |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 RSN  |RSNA Key Management      |   AC      |    AC     |
 +  (WPA2)     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.11              |   WTP     |    WTP/AC |
 +             |Encryption/Decryption    |           |           |
 |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Note:
   RSN - Robust Security Network
   RSNA - Robust Security Network Association
   WPA2 - Wi-Fi Protected Access 2
            Figure 1: Functions in Local MAC and Split MAC
 To solve this problem, this specification introduces the IEEE 802.11
 MAC Profile.  The IEEE 802.11 MAC Profile unambiguously specifies
 where the various MAC functionalities should be located.

Shao, et al. Standards Track [Page 4] RFC 7494 CAPWAP MAC Profile April 2015

2. IEEE MAC Profile Descriptions

 A IEEE 802.11 MAC Profile refers to a description of how the MAC
 functionality is split between the WTP and AC shown in Figure 1.

2.1. Split MAC with WTP Encryption

 The functional split for the Split MAC with WTP encryption is
 provided in Figure 2.  This profile is similar to the Split MAC
 description in [RFC5416], except that IEEE 802.11 encryption/
 decryption is at the WTP.  Note that fragmentation is always done at
 the same entity as the encryption.  Consequently, in this profile
 fragmentation/defragmentation is also done only at the WTP.  Note
 that scheduling functionality is denoted as WTP/AC.  As explained in
 [RFC5416], this means that the admission control component of IEEE
 802.11 resides on the AC; the real-time scheduling and queuing
 functions are on the WTP.

Shao, et al. Standards Track [Page 5] RFC 7494 CAPWAP MAC Profile April 2015

 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Functions                  | Profile   |
 |                                       |    0      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Distribution Service     |   AC      |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Integration Service      |   AC      |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Beacon Generation        |   WTP     |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Probe Response Generation|   WTP     |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Function    |Power Mgmt/              |   WTP     |
 +             |Packet Buffering        |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Fragmentation/           |   WTP     |
 +             |Defragmentation          |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Assoc/Disassoc/Reassoc   |   AC      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Classifying              |   AC      |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 QoS  |Scheduling               |   WTP/AC  |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Queuing                  |   WTP     |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.1X/EAP          |   AC      |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 RSN  |RSNA Key Management      |   AC      |
 +  (WPA2)     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.11              |   WTP     |
 +             |Encryption/Decryption    |           |
 |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Note:
 EAP - Extensible Authentication Protocol
         Figure 2: Functions in Split MAC with WTP Encryption

Shao, et al. Standards Track [Page 6] RFC 7494 CAPWAP MAC Profile April 2015

2.2. Split MAC with AC Encryption

 The functional split for the Split MAC with AC encryption is provided
 in Figure 3.  This profile is similar to the Split MAC in [RFC5416],
 except that IEEE 802.11 encryption/decryption is at the AC.  Since
 fragmentation is always done at the same entity as the encryption, in
 this profile, AC does fragmentation/defragmentation.
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Functions                  | Profile   |
 |                                       |    1      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Distribution Service     |   AC      |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Integration Service      |   AC      |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Beacon Generation        |   WTP     |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Probe Response Generation|   WTP     |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Function    |Power Mgmt/              |   WTP     |
 +             |Packet Buffering         |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Fragmentation/           |   AC      |
 +             |Defragmentation          |           |
 |             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Assoc/Disassoc/Reassoc   |   AC      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Classifying              |   AC      |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 QoS  |Scheduling               |   WTP     |
 +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |Queuing                  |   WTP     |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.1X/EAP          |   AC      |
 +   IEEE      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | 802.11 RSN  |RSNA Key Management      |   AC      |
 +  (WPA2)     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             |IEEE 802.11              |   AC      |
 +             |Encryption/Decryption    |           |
 |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Figure 3: Functions in Split MAC with AC encryption

Shao, et al. Standards Track [Page 7] RFC 7494 CAPWAP MAC Profile April 2015

2.3. IEEE 802.11 MAC Profile Frame Exchange

 An example of message exchange using the IEEE 802.11 MAC Profile
 message element is shown in Figure 4.  The WTP informs the AC of the
 various MAC Profiles it supports.  This happens in either a Discovery
 Request message or the Join Request message.  The AC determines the
 appropriate profile and configures the WTP with the profile while
 configuring the WLAN.
     +-+-+-+-+-+-+                             +-+-+-+-+-+-+
     |    WTP    |                             |    AC     |
     +-+-+-+-+-+-+                             +-+-+-+-+-+-+
           |Join Request[Supported IEEE 802.11       |
           |       MAC Profiles   ]                  |
           |---------------------------------------->|
           |                                         |
           |Join Response                            |
           |<----------------------------------------|
           |                                         |
           |IEEE 802.11 WLAN Config. Request [       |
           | IEEE 802.11 Add WLAN,                   |
           | IEEE 802.11 MAC Profile                 |
           |   ]                                     |
           |<----------------------------------------|
           |                                         |
           |IEEE 802.11 WLAN Config. Response        |
           |---------------------------------------->|
        Figure 4: Message Exchange for Negotiating MAC Profiles

3. MAC Profile Message Element Definitions

3.1. IEEE 802.11 Supported MAC Profiles

 The IEEE 802.11 Supported MAC Profile message element allows the WTP
 to communicate the profiles it supports.  The Discovery Request
 message, Primary Discovery Request message, and Join Request message
 may include one such message element.
         0               1               2               3
         0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0
        +=+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
        | Num_Profiles  |  Profile_1    |   Profile_[2..N]..
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
             Figure 5: IEEE 802.11 Supported MAC Profiles
 o  Type: 1060 for IEEE 802.11 Supported MAC Profiles

Shao, et al. Standards Track [Page 8] RFC 7494 CAPWAP MAC Profile April 2015

 o  Num_Profiles >=1: This refers to the number of profiles present in
    this message element.  There must be at least one profile.
 o  Profile: Each profile is identified by a value specified in
    Section 3.2.

3.2. IEEE 802.11 MAC Profile

 The IEEE 802.11 MAC Profile message element allows the AC to select a
 profile.  This message element may be provided along with the IEEE
 802.11 ADD WLAN message element while configuring a WLAN on the WTP.
         0 1 2 3 4 5 6 7
        +=+-+-+-+-+-+-+-+
        |  Profile      |
        +-+-+-+-+-+-+-+-+
                   Figure 6: IEEE 802.11 MAC Profile
 o  Type: 1061 for IEEE 802.11 MAC Profile
 o  Profile: The profile is identified by a value as given below
  • 0: This refers to the IEEE 802.11 Split MAC Profile with WTP

encryption

  • 1: This refers to the IEEE 802.11 Split MAC Profile with AC

encryption

4. Security Considerations

 This document does not introduce any new security risks compared to
 [RFC5416].  The negotiation messages between the WTP and AC have
 origin authentication and data integrity.  As a result, an attacker
 cannot interfere with the messages to force a less-secure mode
 choice.  The security considerations described in [RFC5416] apply
 here as well.

Shao, et al. Standards Track [Page 9] RFC 7494 CAPWAP MAC Profile April 2015

5. IANA Considerations

 The following IANA actions have been completed.
 o  This specification defines two new message elements: IEEE 802.11
    Supported MAC Profiles (described in Section 3.1) and the IEEE
    802.11 MAC Profile (described in Section 3.2).  These elements
    have been registered in the existing "CAPWAP Message Element Type"
    registry, defined in [RFC5415].
            CAPWAP Protocol Message Element                Type Value
            IEEE 802.11 Supported MAC Profiles              1060
            IEEE 802.11 MAC Profile                         1061
 o  The IEEE 802.11 Supported MAC Profiles message element and IEEE
    802.11 MAC Profile message element include a Profile field (as
    defined in Section 3.2).  The Profile field in the IEEE 802.11
    Supported MAC Profiles denotes the MAC Profiles supported by the
    WTP.  The Profile field in the IEEE 802.11 MAC Profile denotes the
    MAC Profile assigned to the WTP.  The namespace for the field is 8
    bits (0-255).  This specification defines two values: zero (0) and
    one (1) as described below.  The remaining values (2-255) are
    controlled and maintained by IANA, and the registration procedure
    is Expert Review [RFC5226].  IANA has created a new subregistry
    called "IEEE 802.11 Split MAC Profile" under the existing registry
    "Control And Provisioning of Wireless Access Points (CAPWAP)
    Parameters".  The registry format is given below.
             Profile                             Type Value  Reference
             Split MAC with WTP encryption       0           RFC 7494
             Split MAC with AC encryption        1           RFC 7494

Shao, et al. Standards Track [Page 10] RFC 7494 CAPWAP MAC Profile April 2015

6. References

6.1. Normative References

 [IEEE.802.11]
            IEEE, "IEEE Standard for Information Technology -
            Telecommunications and information exchange between
            systems - Local and metropolitan area networks - Specific
            requirements Part 11: Wireless LAN Medium Access Control
            (MAC) and Physical Layer (PHY) Specifications", IEEE Std
            802.11-2012, March 2012,
            <http://standards.ieee.org/about/get/802/802.11.html>.
 [RFC5415]  Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
            Ed., "Control And Provisioning of Wireless Access Points
            (CAPWAP) Protocol Specification", RFC 5415, March 2009,
            <http://www.rfc-editor.org/info/rfc5415>.
 [RFC5416]  Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
            Ed., "Control and Provisioning of Wireless Access Points
            (CAPWAP) Protocol Binding for IEEE 802.11", RFC 5416,
            March 2009, <http://www.rfc-editor.org/info/rfc5416>.

6.2. Informative References

 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            May 2008, <http://www.rfc-editor.org/info/rfc5226>.

Shao, et al. Standards Track [Page 11] RFC 7494 CAPWAP MAC Profile April 2015

Acknowledgments

 The authors are grateful for extremely valuable suggestions from
 Dorothy Stanley in developing this specification.
 Guidance from the management team -- Melinda Shore, Scott Bradner,
 Chris Liljenstolpe, Benoit Claise, Joel Jaeggli, and Dan Romascanu --
 is highly appreciated.

Contributors

 Yifan Chen <chenyifan@chinamobile.com>
 Naibao Zhou <zhounaibao@chinamobile.com>

Authors' Addresses

 Chunju Shao
 China Mobile
 No.32 Xuanwumen West Street
 Beijing  100053
 China
 EMail: shaochunju@chinamobile.com
 Hui Deng
 China Mobile
 No.32 Xuanwumen West Street
 Beijing  100053
 China
 EMail: denghui@chinamobile.com
 Rajesh S. Pazhyannur
 Cisco Systems
 170 West Tasman Drive
 San Jose, CA 95134
 United States
 EMail: rpazhyan@cisco.com

Shao, et al. Standards Track [Page 12] RFC 7494 CAPWAP MAC Profile April 2015

 Farooq Bari
 AT&T
 7277 164th Ave NE
 Redmond, WA 98052
 United States
 EMail: farooq.bari@att.com
 Rong Zhang
 China Telecom
 No.109 Zhongshandadao avenue
 Guangzhou  510630
 China
 EMail: zhangr@gsta.com
 Satoru Matsushima
 SoftBank Telecom
 1-9-1 Higashi-Shinbashi, Munato-ku
 Tokyo
 Japan
 EMail: satoru.matsushima@g.softbank.co.jp

Shao, et al. Standards Track [Page 13]

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