Network Working Group C. Shao
Internet-Draft H. Deng
Intended status: Standards Track China Mobile
Expires: August 18, 2014 R. Pazhyannur
Cisco
F. Bari
AT&T
R. Zhang
China Telecom
S. Matsushima
SoftBank Telecom
February 14, 2014
IEEE 802.11 MAC Profile for CAPWAP
draft-ietf-opsawg-capwap-hybridmac-02
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 for the Split MAC mode, 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 unambigous 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 a WLAN.
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
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 August 18, 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,
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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 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 | WTP | 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
profle. The MAC profile unamabigously specifies where the various
MAC fucntionality 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
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
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/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 except that
IEEE 802.11 encryption/decryption is done only at the AC. Since
fragmentation is always done at the same entity as the encryption, in
this rofile, 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/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 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.
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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
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 messaage element. There must be at least one profile.
o Profile: Each profile is idnentified by a value specified in
Section 4.2.
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4.2. IEEE 802.11 MAC Profile
The IEEE 802.11 MAC Profile message element allows the AC to select a
profile. This messsage 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 security risk difference from
[RFC5416]. Please refer to the Security section of [RFC5416]
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 regsitered 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 regsitered 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.
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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.
[RFC4564] Govindan, S., Cheng, H., Yao, ZH., Zhou, WH., and L. Yang,
"Objectives for Control and Provisioning of Wireless
Access Points (CAPWAP)", RFC 4564, July 2006.
[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
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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