Network Working Group C. Shao
Internet-Draft H. Deng
Intended status: Standards Track China Mobile
Expires: February 12, 2015 R. Pazhyannur
Cisco Systems
F. Bari
AT&T
R. Zhang
China Telecom
S. Matsushima
SoftBank Telecom
August 11, 2014
IEEE 802.11 MAC Profile for CAPWAP
draft-ietf-opsawg-capwap-hybridmac-06
Abstract
The CAPWAP protocol defines two entities: a Wireless Transmission
Point (WTP) and an Access Controller (AC). The CAPWAP protocol
binding for IEEE 802.11 defines two MAC (Medium Access Control) modes
for IEEE 802.11 WTP: Split and Local MAC, and describes the required
functionality split between the WTP and AC for each mode. However,
in the split MAC mode, the partitioning of encryption/decryption
functions are not been clearly clearly defined. In the Split MAC
mode description, IEEE 802.11 encryption is specified as located in
either at the AC or the WTP, with no clear way for the AC to inform
the WTP of where the encryption functionality should be located.
This lack of specification 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. 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 when
configuring the 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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on February 12, 2015.
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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
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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.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 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
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
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controlled and maintained by IANA and require an Expert Review.
IANA needs to create a registry called CAPWAP IEEE 802.11 Split
MAC Profile. 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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