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Versions: (draft-shao-opsawg-capwap-hybridmac) 00 01 02 03 04 05 06 07 08 RFC 7494

Network Working Group                                            C. Shao
Internet-Draft                                                   H. Deng
Intended status: Standards Track                            China Mobile
Expires: June 21, 2015                                     R. Pazhyannur
                                                           Cisco Systems
                                                                 F. Bari
                                                                    AT&T
                                                                R. Zhang
                                                           China Telecom
                                                           S. Matsushima
                                                        SoftBank Telecom
                                                       December 18, 2014


                   IEEE 802.11 MAC Profile for CAPWAP
                 draft-ietf-opsawg-capwap-hybridmac-08

Abstract

   The CAPWAP protocol binding for IEEE 802.11 defines two MAC (Medium
   Access Control) modes for IEEE 802.11 WTP (Wireless Transmission
   Point): Split and Local MAC.  In the Split MAC mode, the partitioning
   of encryption/decryption functions are not clearly defined.  In the
   Split MAC mode description, IEEE 802.11 encryption is specified as
   located in either the AC (Access Controller) 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 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."




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   This Internet-Draft will expire on June 21, 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
   (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
   2.  IEEE MAC Profile Descriptions . . . . . . . . . . . . . . . .   4
     2.1.  Split MAC with WTP encryption . . . . . . . . . . . . . .   4
     2.2.  Split MAC with AC encryption  . . . . . . . . . . . . . .   5
     2.3.  IEEE 802.11 MAC Profile  Frame Exchange . . . . . . . . .   6
   3.  MAC Profile Message Element Definitions . . . . . . . . . . .   7
     3.1.  IEEE 802.11 Supported MAC Profiles  . . . . . . . . . . .   7
     3.2.  IEEE 802.11 MAC Profile . . . . . . . . . . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The CAPWAP protocol supports two MAC modes of operation: Split and
   Local MAC, as described in [RFC5415], [RFC5416].  However, there are
   MAC functions that have not been clearly defined.  For example IEEE
   802.11 encryption is specified as located in either in 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




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   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.


   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            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    |           |           |
   |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 1: Functions in Local MAC and Split MAC






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   To solve this problem, this specification introduces IEEE 802.11 MAC
   profile.  The MAC profile unambiguously specifies where the various
   MAC functionality should be located.

2.  IEEE MAC Profile Descriptions

   A IEEE 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.






























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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            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    |           |
   |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 2: Functions in Split MAC with WTP Encryption

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.








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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            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

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 either in 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.







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       +-+-+-+-+-+-+                             +-+-+-+-+-+-+
       |    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 Profile

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: TBD for IEEE 802.11 Supported MAC Profiles
   o  Num_Profiles >=1: This refers to 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.







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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: TBD for IEEE 802.11 MAC Profile
   o  Profile: The profile is identified by a value as given below

      *  0: This refers to the Split MAC Profile with WTP encryption
      *  1: This refers to the 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.

5.  IANA Considerations

   This document requires the following IANA actions:

   o  This specification defines two new message elements, IEEE 802.11
      Supported MAC Profiles (described in Section 3.1) and IEEE 802.11
      MAC Profile (described in Section 3.2).  These elements needs to
      be registered in the existing CAPWAP Message Element Type
      registry, defined in [RFC5415].  The values for these elements
      needs to be between 1024 and 2047 (see Section 15.7 in [RFC5415]).

              CAPWAP Protocol Message Element                Type Value
              IEEE 802.11 Supported MAC Profiles              TBD1
              IEEE 802.11 MAC Profile                         TBD2
   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 MAC profile denotes MAC



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      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 require an Expert Review.
      IANA needs to create a new sub-registry called IEEE 802.11 Split
      MAC Profile and add the new sub-registry to 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
             Split MAC with AC encryption        1


6.  Contributors

   Yifan Chen chenyifan@chinamobile.com

   Naibao Zhou zhounaibao@chinamobile.com

7.  Acknowledgments

   The authors are grateful for extremely valuable suggestions from
   Dorothy Stanley in developing this specification.

   Guidance from management team: Melinda Shore, Scott Bradner, Chris
   Liljenstolpe, Benoit Claise, Joel Jaeggli, Dan Romascanu are highly
   appreciated.

8.  Normative References

   [RFC5415]  Calhoun, P., Montemurro, M., and D. Stanley, "Control And
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Specification", RFC 5415, March 2009.

   [RFC5416]  Calhoun, P., Montemurro, M., and D. Stanley, "Control and
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Binding for IEEE 802.11", RFC 5416, March 2009.

Authors' Addresses

   Chunju Shao
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: shaochunju@chinamobile.com



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   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
   USA

   Email: rpazhyan@cisco.com


   Farooq Bari
   AT&T
   7277 164th Ave NE
   Redmond WA 98052
   USA

   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








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