Network Working Group C. Shao Internet-Draft H. Deng Intended status: Standards Track China Mobile Expires: June 6, 2015 R. Pazhyannur Cisco Systems F. Bari AT&T R. Zhang China Telecom S. Matsushima SoftBank Telecom December 3, 2014 IEEE 802.11 MAC Profile for CAPWAP draft-ietf-opsawg-capwap-hybridmac-07 Abstract The Control And Provisioning of Wireless Access Points (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 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/. Shao, et al. Expires June 6, 2015 [Page 1] Internet-Draft CAPWAP MAC Profile December 2014 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." This Internet-Draft will expire on June 6, 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 . . . . . . . . . . . . . . 5 2.2. Split MAC with AC encryption . . . . . . . . . . . . . . 6 2.3. IEEE 802.11 MAC Profile Frame Exchange . . . . . . . . . 7 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 . . . . . . . . . . . . . . . . . . . . . 9 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 8. Normative References . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 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 Shao, et al. Expires June 6, 2015 [Page 2] Internet-Draft CAPWAP MAC Profile December 2014 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 Access Controller. Shao, et al. Expires June 6, 2015 [Page 3] Internet-Draft CAPWAP MAC Profile December 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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 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. Shao, et al. Expires June 6, 2015 [Page 4] Internet-Draft CAPWAP MAC Profile December 2014 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. Expires June 6, 2015 [Page 5] Internet-Draft CAPWAP MAC Profile December 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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. Shao, et al. Expires June 6, 2015 [Page 6] Internet-Draft CAPWAP MAC Profile December 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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. Shao, et al. Expires June 6, 2015 [Page 7] Internet-Draft CAPWAP MAC Profile December 2014 +-+-+-+-+-+-+ +-+-+-+-+-+-+ | 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. Shao, et al. Expires June 6, 2015 [Page 8] Internet-Draft CAPWAP MAC Profile December 2014 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 between the WTP and AC is encrypted and as a result an attacker cannot interfere with it 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 profile assigned to the WTP. The namespace for the field is 8 Shao, et al. Expires June 6, 2015 [Page 9] Internet-Draft CAPWAP MAC Profile December 2014 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 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 Shao, et al. Expires June 6, 2015 [Page 10] Internet-Draft CAPWAP MAC Profile December 2014 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 Shao, et al. Expires June 6, 2015 [Page 11]