Network Working Group                                            C. Shao
Internet-Draft                                                   H. Deng
Intended status: Standards Track                            China Mobile
Expires: November 6, 2014                                  R. Pazhyannur
                                                           Cisco Systems
                                                                 F. Bari
                                                                    AT&T
                                                                R. Zhang
                                                           China Telecom
                                                           S. Matsushima
                                                        SoftBank Telecom
                                                             May 5, 2014

                   IEEE 802.11 MAC Profile for CAPWAP
                 draft-ietf-opsawg-capwap-hybridmac-03
                 draft-ietf-opsawg-capwap-hybridmac-04

Abstract

   CAPWAP defines two entities: Wireless Transmission Point (WTP) and
   Access Controller (AC).  CAPWAP also defines two MAC (Medium Access
   Control) modes for IEEE 802.11 WTPs: Split and Local MAC . For each
   MAC mode, CAPWAP describes how the MAC functionality is split between
   the WTP and AC.  However, certain functions have not been clearly
   defined.  For example in the Split MAC mode description, the IEEE
   802.11 encryption is specified as located in either the AC or the WTP
   with no clear way for the AC to inform the WTP where it should be.
   This lack of specification leads to interoperability especially when
   AC and WTP come from different vendors.  To solve the problem, this
   specification defines a IEEE 802.11 MAC profile where each profile
   specifies an unambiguous division of functionality between the WTP
   and AC.  The IEEE 802.11 MAC profile is used as follows: the WTP
   informs the AC of the supported profiles during the discovery or join
   process and the AC configures the WTP with one of the supported
   profiles while configuring the WLAN.

Status of This Memo

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   This Internet-Draft will expire on November 6, 2014.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   4
   3.  IEEE MAC Profile Descriptions . . . . . . . . . . . . . . . .   4
     3.1.  Split MAC with WTP encryption . . . . . . . . . . . . . .   4
     3.2.  Split MAC with AC encryption  . . . . . . . . . . . . . .   5
     3.3.  IEEE 802.11 MAC Profile  Frame Exchange . . . . . . . . .   6
   4.  MAC Profile Message Element Definitions . . . . . . . . . . .   7
     4.1.  IEEE 802.11 Supported MAC Profiles  . . . . . . . . . . .   7
     4.2.  IEEE 802.11 MAC Profile . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   9.  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 their own definition 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 difficulty in interoperating WTPs and ACs from different
   vendors.

   Figure 1 is quoted from [RFC5416], illustrates how the 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.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            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/EWTP         |   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

   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.  Conventions used in this document

   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.  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 1.

3.1.  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.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            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/EWTP         |   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

3.2.  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/EWTP         |   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

3.3.  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 the 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 Profile

4.  MAC Profile Message Element Definitions

4.1.  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 idnentified by a value specified in
      Section 4.2.

4.2.  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

5.  Security Considerations

   This document doesn't specify does not introduce any new security risk difference from
   [RFC5416].  Please refer risks compared to the Security section of
   [RFC5416].  The security considerations described in [RFC5416] apply
   here as well.

6.  IANA Considerations

   This document requires the following IANA actions.

   o  This specification defines a new message element, IEEE 802.11
      Supported MAC Profiles.  The format of this option is described in
      Section 4.1.  This value needs to be registered in the existing
      CAPWAP Message Element Type registry, defined in [RFC5415].
   o  This specification defines a new message element, IEEE 802.11 MAC
      Profile.  The format of this option is described in Section 4.2.
      This value needs to be registered in the existing CAPWAP Message
      Element Type registry, defined in [RFC5415].
   o  The Profile field in the IEEE 802.11 Supported MAC Profiles
      message element and IEEE 802.11 MAC Profile message element (see
      Section 4.2) is used to denote the MAC profile.  This document
      defines two values, zero (0) and one (1), and the remaining values
      (2-255) are controlled and maintained by IANA and require an
      Expert Review.

7.  Contributors

   Yifan Chen chenyifan@chinamobile.com

   Naibao Zhou zhounaibao@chinamobile.com

8.  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.

9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [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

   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