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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet has text resembling RFC 2119 boilerplate text. -- The document date (February 18, 2013) is 4084 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'RFC4564' is defined on line 286, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Shao 3 Internet-Draft H. Deng 4 Intended status: Informational China Mobile 5 Expires: August 22, 2013 F. Bari 6 AT&T 7 R. Zhang 8 China Telecom 9 S. Matsushima 10 SoftBank Telecom 11 February 18, 2013 13 Hybrid-MAC Model for CAPWAP 14 draft-shao-opsawg-capwap-hybridmac-00 16 Abstract 18 The CAPWAP protocol supports two modes of operation: Split and Local 19 MAC (medium access control), which has been described in 20 [RFC5415].There are many functions in IEEE 802l.11 MAC layer that 21 have not yet been clearly defined whether they belong to either the 22 AP (Access Point) or the AC (Access Controller)in the Split and Local 23 modes. Because different vendors have their own definition of these 24 two models, depending upon the vendor many MAC layer functions 25 continue to be mapped differently to either the AP or AC. If there 26 is no clear definition of split MAC and local MAC, then operators 27 will not only need to perform vendor specific configurations in their 28 network but will continue to experience difficulty in interoperating 29 APs and ACs from different vendors. 31 Status of this Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on August 22, 2013. 48 Copyright Notice 49 Copyright (c) 2013 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2. Conventions used in this document . . . . . . . . . . . . . . . 3 66 3. The difference between Local MAC and Split MAC . . . . . . . . 3 67 4. Functions in Local MAC and Split MAC . . . . . . . . . . . . . 4 68 5. Hybrid-MAC model recommendation . . . . . . . . . . . . . . . . 5 69 6. Hybrid-MAC model Frames Exchange . . . . . . . . . . . . . . . 6 70 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 71 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 72 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 8 73 10. Normative References . . . . . . . . . . . . . . . . . . . . . 8 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 76 1. Introduction 78 The CAPWAP protocol supports two modes of operation: Split and Local 79 MAC (medium access control), which has been described in [RFC5415].In 80 Split MAC mode, all L2 wireless data and management frames are 81 encapsulated via the CAPWAP protocol and exchanged between the AC and 82 the AP. The Local MAC mode of operation allows for the data frames 83 to be either locally bridged or tunneled as 802.3 frames. The latter 84 implies that the AP performs the 802.11 Integration function. 85 Unfortunately, there are many functions that have not yet been 86 clearly defined whether they belong to either the AP or the AC in the 87 Split and Local modes. Because different vendors have their own 88 definition of the two models, many MAC layer functions are mapped 89 differently to either the AP or the AC by different vendors. 90 Therefore, depending upon the vendor, the operators in their 91 deployments have to perform different configurations based on 92 implementation of the two modes by their vendor. If there is no 93 clear definition of split MAC and local MAC, then operators will 94 continue to experience difficulty in interoperating APs and ACs from 95 different vendors. 97 2. Conventions used in this document 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 101 document are to be interpreted as described in [RFC2119]. 103 3. The difference between Local MAC and Split MAC 105 The main difference between Local MAC and Split MAC lies in the 106 processing of the wireless frames. This is shown in Figure 1 where 107 depending upon the mode, either the AP or the AC performs the 802.11 108 Integration function. According to the 802.11 protocol definition, 109 the 802.11 wireless frame is divided into three kinds of frames, 110 including wireless control frames, wireless management frames, and 111 wireless data frames. 113 WWireless control frames, such as TS, CTS, ACK, PS-POLL, etc., are 114 processed locally by AP in both Local MAC and Split MAC. However, 115 wireless management frames, including Beacon, Probe, Association, 116 Authentication, are processed differently in the Local MAC and the 117 Split MAC. In the Local MAC, depending upon the vendor wireless 118 management frames can be processed in the AP or the AC. In the case 119 of Split MAC, the real-time part of wireless frames are processed in 120 AP, while the non-real-time frames are processed in the AC. This is 121 shown in Figure 2. In Split MAC mode, the wireless data frames 122 received from a mobile device are directly encapsulated by the AP and 123 forwarded to the AC. The Local MAC mode of operation allows data 124 frames to be processed locally by the AP and then forwarded to the 125 AC. 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Local MAC | Split MAC | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | | | 802.3 MAC | | 131 + 802.3 MAC + AC +-+-+-+-+-+-+-+-+- AC + 132 | | | 802.11MAC NonRT| | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | 802.11 MAC | | 802.11 MAC RT | | 135 +-+-+-+-+-+-+-+-+ AP +-+-+-+-+-+-+-+-+- AP + 136 | 802.11 PHY | | 802.11 PHY | | 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 Figure 1: The comparison between Local MAC and Split MAC 141 4. Functions in Local MAC and Split MAC 143 As shown in Figure 2, main functions are processed in different 144 places in the Local MAC and Split MAC. In addition, for some 145 functions (for example, the Frag. / Defrag. Assoc. / Disassoc / 146 Reassoc., Etc.) the protocol does not explicitly map processing of 147 such functions to the AP or the AC. Therefore the location of these 148 features becomes vendor specific and this increases the difficulty of 149 interoperability between APs and ACs from different vendors. 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | Functions describe | Loacal MAC| Split MAC | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | |Distribution Service | AP/AC | AC | 155 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | |Integration Service | AP | AC | 157 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | |Beacon Generation | AP | AP | 159 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | |Probe Response Generation| AP | AP | 161 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | Function |Power Mgmt | AP | AP | 163 + |/Packet Buffering | | | 164 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 | |Fragmentation | AP | AP/AC | 166 + |/Defragmentation | | | 167 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 | |Assoc/Disassoc/Reassoc | AP/AC | AC | 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 | |Classifying | AP | AC | 171 + IEEE +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 | 802.11 QoS |Scheduling | AP | AP/AC | 173 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 | |Queuing | AP | AP | 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | |IEEE 802.1X/EAP | AC | AC | 177 + IEEE +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | 802.11 RSN |RSNA Key Management | AP | AC | 179 + (WPA2) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | |IEEE 802.11 | AP | AP/AC | 181 + |Encryption/Decryption | | | 182 |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 Figure 2: Functions in Local MAC and Split MAC 186 5. Hybrid-MAC model recommendation 188 As discussed above, if the functions have been clearly defined to be 189 implemented in AP or AC, the interoperability will be much better 190 between different vendors products. To achieve this goal a common 191 Hybrid-MAC model, as shown in Figure 3, is proposed. 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | Functions describe | Hybrid-MAC| 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | |Distribution Service | AC | 197 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | |Integration Service | AC | 199 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | |Beacon Generation | AP | 201 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | |Probe Response Generation| AP | 203 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Function |Power Mgmt | AP | 205 + |/Packet Buffering | | 206 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | |Fragmentation | AC | 208 + |/Defragmentation | | 209 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | |Assoc/Disassoc/Reassoc | AC | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | |Classifying | AC | 213 + IEEE +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | 802.11 QoS |Scheduling | AP | 215 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | |Queuing | AP | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | |IEEE 802.1X/EAP | AC | 219 + IEEE +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | 802.11 RSN |RSNA Key Management | AC | 221 + (WPA2) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | |IEEE 802.11 | AP | 223 + |Encryption/Decryption | | 224 |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 Figure 3: Functions in Hybrid MAC 228 6. Hybrid-MAC model Frames Exchange 230 An example of frame exchange using the proposed Hybrid-MAC Model 231 shown in Figure 4. 233 +-+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+-+ 234 | STA | | AP | | AC | 235 +-+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+-+ 236 | | | 237 | Beacon | | 238 |<-------------------------| | 239 | Probe | | 240 |<------------------------>| | 241 | 802.11 AUTH/Association | 242 |<-------------------------------------------------------->| 243 | |Station Configuration Request [| 244 | Add Station (Station MAC Address),| 245 | IEEE 802.11 Add Station (WLAN ID),| 246 | IEEE 802.11 Session Key(Flag=A)] | 247 | |<------------------------------| 248 | | | 249 | |Station Configuration Response | 250 | |------------------------------>| 251 | 802.1X Authentication & 802.11 Key Exchange | 252 |<-------------------------------------------------------->| 253 | |Station Configuration Request [| 254 | Add Station (Station MAC Address),| 255 | IEEE 802.11 Add Station (WLAN ID),| 256 | IEEE 802.11 Station Session Key] | 257 | |<------------------------------| 258 | | | 259 | |Station Configuration Response | 260 | |------------------------------>| 261 | 802.11 Action Frames | 262 |<-------------------------------------------------------->| 263 | DATA Frame Exchange | 264 | 802.11 Data | 802.11 or 802.3 Data | 265 |<-------------------------+------------------------------>| 267 Figure 4: Hybrid-MAC model Frames Exchange 269 7. Security Considerations 271 TBD 273 8. IANA Considerations 275 None 277 9. Contributors 279 Naibao Zhou zhounaibao@chinamobile.com 281 10. Normative References 283 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 284 Requirement Levels", BCP 14, RFC 2119, March 1997. 286 [RFC4564] Govindan, S., Cheng, H., Yao, ZH., Zhou, WH., and L. Yang, 287 "Objectives for Control and Provisioning of Wireless 288 Access Points (CAPWAP)", RFC 4564, July 2006. 290 [RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And 291 Provisioning of Wireless Access Points (CAPWAP) Protocol 292 Specification", RFC 5415, March 2009. 294 Authors' Addresses 296 Chunju Shao 297 China Mobile 298 No.32 Xuanwumen West Street 299 Beijing 100053 300 China 302 Email: shaochunju@chinamobile.com 304 Hui Deng 305 China Mobile 306 No.32 Xuanwumen West Street 307 Beijing 100053 308 China 310 Email: denghui@chinamobile.com 312 Farooq Bari 313 AT&T 314 7277 164th Ave NE 315 Redmond WA 98052 316 USA 318 Email: farooq.bari@att.com 319 Rong Zhang 320 China Telecom 321 No.109 Zhongshandadao avenue 322 Tianhe District, 323 Guangzhou 510630 324 China 326 Email: zhangr@gsta.com 328 Satoru Matsushima 329 SoftBank Telecom 330 1-9-1 Higashi-Shinbashi, Munato-ku 331 Tokyo 332 Japan 334 Email: satoru.matsushima@g.softbank.co.jp