idnits 2.17.1 draft-ietf-opsawg-capwap-alt-tunnel-09.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 2, 2017) is 2548 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) == Outdated reference: A later version (-13) exists of draft-ietf-intarea-tunnels-05 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Opsawg Working Group R. Zhang 3 Internet-Draft China Telecom 4 Intended status: Standards Track R. Pazhyannur 5 Expires: November 3, 2017 S. Gundavelli 6 Cisco 7 Z. Cao 8 H. Deng 9 Z. Du 10 Huawei 11 May 2, 2017 13 Alternate Tunnel Encapsulation for Data Frames in CAPWAP 14 draft-ietf-opsawg-capwap-alt-tunnel-09 16 Abstract 18 Control and Provisioning of Wireless Access Points (CAPWAP) defines a 19 specification to encapsulate a station's data frames between the 20 Wireless Transmission Point (WTP) and Access Controller (AC). 21 Specifically, the station's IEEE 802.11 data frames can be either 22 locally bridged or tunneled to the AC. When tunneled, a CAPWAP data 23 channel is used for tunneling. In many deployments encapsulating 24 data frames to an entity other than the AC (for example to an Access 25 Router (AR)) is desirable. Furthermore, it may also be desirable to 26 use different tunnel encapsulation modes between the WTP and the 27 Access Router. This document defines extension to CAPWAP protocol 28 for supporting this capability and refers to it as alternate tunnel 29 encapsulation. The alternate tunnel encapsulation allows 1) the WTP 30 to tunnel non-management data frames to an endpoint different from 31 the AC and 2) the WTP to tunnel using one of many known encapsulation 32 types such as IP-IP, IP-GRE, CAPWAP. The WTP may advertise support 33 for alternate tunnel encapsulation during the discovery and join 34 process and AC may select one of the supported alternate tunnel 35 encapsulation types while configuring the WTP. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at http://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on November 3, 2017. 54 Copyright Notice 56 Copyright (c) 2017 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (http://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 72 1.1. Conventions used in this document . . . . . . . . . . . . 7 73 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 74 2. Alternate Tunnel Encapsulation Overview . . . . . . . . . . . 8 75 3. CAPWAP Protocol Message Elements Extensions . . . . . . . . . 11 76 3.1. Supported Alternate Tunnel Encapsulations . . . . . . . . 11 77 3.2. Alternate Tunnel Encapsulations Type . . . . . . . . . . 11 78 3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication . . . 12 79 4. Alternate Tunnel Types . . . . . . . . . . . . . . . . . . . 13 80 4.1. CAPWAP based Alternate Tunnel . . . . . . . . . . . . . . 13 81 4.2. PMIPv6 based Alternate Tunnel . . . . . . . . . . . . . . 14 82 4.3. GRE based Alternate Tunnel . . . . . . . . . . . . . . . 15 83 5. Alternate Tunnel Information Elements . . . . . . . . . . . . 15 84 5.1. Access Router Information Elements . . . . . . . . . . . 15 85 5.1.1. AR IPv4 List Element . . . . . . . . . . . . . . . . 16 86 5.1.2. AR IPv6 List Element . . . . . . . . . . . . . . . . 16 87 5.2. Tunnel DTLS Policy Element . . . . . . . . . . . . . . . 17 88 5.3. IEEE 802.11 Tagging Mode Policy Element . . . . . . . . . 18 89 5.4. CAPWAP Transport Protocol Element . . . . . . . . . . . . 20 90 5.5. GRE Key Element . . . . . . . . . . . . . . . . . . . . . 20 91 5.6. IPv6 MTU Element . . . . . . . . . . . . . . . . . . . . 21 92 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 93 7. Security Considerations . . . . . . . . . . . . . . . . . . . 23 94 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 23 95 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 96 9.1. Normative References . . . . . . . . . . . . . . . . . . 23 97 9.2. Informative References . . . . . . . . . . . . . . . . . 24 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 100 1. Introduction 102 Service Providers are deploying very large Wi-Fi deployments (ranging 103 from hundreds of thousands of Access Points, APs (referred to as WTPs 104 in CAPWAP terminology) to millions of APs. These networks are 105 designed to carry traffic generated from mobile users. The volume in 106 mobile user traffic is already very large and expected to continue 107 growing rapidly. As a result, operators are looking for scalable 108 solutions that can meet the increasing demand. The scalability 109 requirement can be met by splitting the control/management plane from 110 the data plane. This enables the data plane to scale independent of 111 the control/management plane. This specification provides a way to 112 enable such separation. 114 CAPWAP ([RFC5415], [RFC5416]) defines a tunnel mode that describes 115 how the WTP handles the data plane (user traffic). The following 116 types are defined: 118 o Local Bridging: All data frames are locally bridged. 119 o 802.3 Tunnel: All data frames are tunneled to the AC in 802.3 120 format. 121 o 802.11 Tunnel: All data frames are tunneled to the AC in 802.11 122 format. 124 Figure 1 describes a system with Local Bridging. The AC is in a 125 centralized location. The data plane is locally bridged by the WTPs 126 leading to a system with centralized control plane with distributed 127 data plane. This system has two benefits: 1) reduces the scale 128 requirement on data traffic handling capability of the AC and 2) 129 leads to more efficient/optimal routing of data traffic while 130 maintaining centralized control/management. 132 Locally Bridged 133 +-----+ Data Frames +----------------+ 134 | WTP |===============| Access Router | 135 +-----+ +----------------+ 136 \\ 137 \\ CAPWAP Control Channel +----------+ 138 ++=========================| AC | 139 // CAPWAP Data Channel: | | 140 // IEEE 802.11 Mgmt traffic +----------+ 141 // 142 +-----+ +----------------+ 143 | WTP |============== | Access Router | 144 +-----+ +----------------+ 145 Locally Bridged 146 Data Frames 148 Figure 1: Centralized Control with Distributed Data 150 The AC handles control of WTPs. In addition, the AC also handles the 151 IEEE 802.11 management traffic to/from the stations. There is CAPWAP 152 Control and Data Channel between the WTP and the AC. Note that even 153 though there is no user traffic transported between the WTP and AC, 154 there is still a CAPWAP Data Channel. The CAPWAP Data Channel 155 carries the IEEE 802.11 management traffic (like IEEE 802.11 Action 156 Frames). 158 Figure 2 shows a system where the tunnel mode is configured to tunnel 159 data frames between the WTP and the AC either using 802.3 Tunnel or 160 802.11 Tunnel configurations. Operators deploy this configuration 161 when they need to tunnel the user traffic. The tunneling requirement 162 may be driven by the need to apply policy at the AC or a legal 163 requirement to support lawful intercept of user traffic. This 164 requirement could be met in the locally bridged system (Figure 1) if 165 the access router implemented the required policy. However, in many 166 deployments the operator managing the WTP is different than the 167 operator managing the Access Router. When the operators are 168 different, the policy has to be enforced in a tunnel termination 169 point in the WTP operator's network. 171 +-----+ 172 | WTP | 173 +-----+ 174 \\ 175 \\ CAPWAP Control Channel +----------+ 176 ++=========================| AC | 177 // CAPWAP Data Channel: | | 178 // IEEE 802.11 Mgmt traffic | | 179 // Data Frames +----------+ 180 // 181 +-----+ 182 | WTP | 183 +-----+ 185 Figure 2: Centralized Control and Centralized Data 187 The key difference with the locally bridged system is that the data 188 frames are tunneled to the AC instead of being locally bridged. 189 There are two shortcomings with system in Figure 2. 1) They do not 190 allow the WTP to tunnel data frames to an endpoint different from the 191 AC and 2) They do not allow the WTP to tunnel data frames using any 192 encapsulation other than CAPWAP (as specified in Section 4.4.2 of 193 [RFC5415]). 195 Figure 3 shows a system where the WTP tunnels data frames to an 196 alternate entity different from the AC. The WTP also uses an 197 alternate tunnel encapsulation such as such as L2TP, L2TPv3, IP-in- 198 IP, IP/GRE, etc. This enables 1) independent scaling of data plane 199 and 2) leveraging of commonly used tunnel encapsulations such as 200 L2TP, GRE, etc. 202 Alternate Tunnel to AR (L2TPv3, IP-IP, CAPWAP, etc.) 203 _________ 204 +-----+ ( ) +-----------------+ 205 | WTP |======+Internet +==============|Access Router(AR)| 206 +-----+ (_________) +-----------------+ 207 \\ ________ CAPWAP Control 208 \\ ( ) Channel +--------+ 209 ++=+Internet+========================| AC | 210 // (________)CAPWAP Data Channel: +--------+ 211 // IEEE 802.11 Mgmt traffic 212 // _________ 213 +-----+ ( ) +----------------+ 214 | WTP |====+Internet +================| Access Router | 215 +-----+ (_________) +----------------+ 216 Alternate Tunnel to AR (L2TPv3, IP-IP, CAPWAP, etc.) 218 Figure 3: Centralized Control with Alternate Tunnel for Data 220 The WTP may support widely used encapsulation types such as L2TP, 221 L2TPv3, IP-in-IP, IP/GRE, etc. The WTP advertises the different 222 alternate tunnel encapsulation types it can support. The AC 223 configures one of the advertised types. As shown in the figure there 224 is a CAPWAP control and data channel between the WTP and AC. The 225 CAPWAP data channel carries the stations' management traffic as in 226 the case of the locally bridged system. The main reason to maintain 227 a CAPWAP data channel is to maintain similarity with the locally 228 bridged system. The WTP maintains three tunnels: CAPWAP Control, 229 CAPWAP Data, and another alternate tunnel for the data frame. The 230 data frames are transported by an alternate tunnel between the WTP 231 and a tunnel termination point such as an Access Router. This 232 specification describes how the alternate tunnel can be established. 233 The specification defines message elements for the WTP to advertise 234 support for alternate tunnel encapsulation, the AC to configure 235 alternate tunnel encapsulation, and for the WTP to report failure of 236 the alternate tunnel. 238 The alternate tunnel encapsulation also supports the third-party WLAN 239 service provider scenario (i.e. Virtual Network Operator, VNO). 240 Under this scenario, the WLAN provider owns the WTP and AC resources, 241 while the VNOs can rent the WTP resources from the WLAN provider for 242 network access. The AC belonging to the WLAN service provider 243 manages the WTPs in the centralized mode. 245 As shown in Figure 4, VNO 1&2 don't possess the network access 246 resources, however they provide services by acquiring resources from 247 the WLAN provider. Since a WTP is capable of supporting up to 16 248 Service Set Identifiers (SSIDs), the WLAN provider may provide 249 network access service for different providers with different SSIDs. 250 For example, SSID1 is advertised by the WTP for VNO1; while SSID2 is 251 advertised by the WTP for VNO2. Therefore the data traffic from the 252 user can be directly steered to the corresponding access router of 253 the VNO who owns that user. AC can notify multiple AR addresses for 254 load balancing or redundancy. 256 +----+ 257 | AC | 258 +--+-+ 259 CAPWAP-CTL | 260 +-----------------+ 261 | CAPWAP-DATA: IEEE 802.11 Mgmt traffic 262 | 263 WLAN Provider| VNO 1 264 +-----+ CAPWAP-DATA (SSID1) +---------------+ 265 SSID1 | WTP +--------------------------|Access Router 1| 266 SSID2 +--+-++ +---------------+ 267 | | 268 | | VNO 1 269 | | GRE-DATA (SSID1) +---------------+ 270 | +---------------------------|Access Router 2| 271 | +---------------+ 272 | 273 | VNO 2 274 | CAPWAP-DATA (SSID2) +---------------+ 275 +-----------------------------|Access Router 3| 276 +---------------+ 278 Figure 4: Third-party WLAN Service Provider 280 1.1. Conventions used in this document 282 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 283 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 284 document are to be interpreted as described in [RFC2119]. 286 1.2. Terminology 288 Station (STA): A device that contains an IEEE 802.11 conformant 289 medium access control (MAC) and physical layer (PHY) interface to the 290 wireless medium (WM). 292 Access Controller (AC): The network entity that provides WTP access 293 to the network infrastructure in the data plane, control plane, 294 management plane, or a combination therein. 296 Access Router (AR): A specialized router usually residing at the edge 297 or boundary of a network. This router ensures the connectivity of 298 its network with external networks, a wide area network or the 299 Internet. 301 Wireless Termination Point (WTP): The physical or network entity that 302 contains an RF antenna and wireless Physical Layer (PHY) to transmit 303 and receive station traffic for wireless access networks. 305 CAPWAP Control Channel: A bi-directional flow defined by the AC IP 306 Address, WTP IP Address, AC control port, WTP control port, and the 307 transport-layer protocol (UDP or UDP-Lite) over which CAPWAP Control 308 packets are sent and received. 310 CAPWAP Data Channel: A bi-directional flow defined by the AC IP 311 Address, WTP IP Address, AC data port, WTP data port, and the 312 transport-layer protocol (UDP or UDP-Lite) over which CAPWAP Data 313 packets are sent and received. In certain WTP modes, the CAPWAP Data 314 Channel only transports IEEE 802.11 management frames and not the 315 data plane (user traffic). 317 2. Alternate Tunnel Encapsulation Overview 318 +-+-+-+-+-+-+ +-+-+-+-+-+-+ 319 | WTP | | AC | 320 +-+-+-+-+-+-+ +-+-+-+-+-+-+ 321 |Join Request[Supported Alternate Tunnel | 322 | Encapsulations ] | 323 |---------------------------------------->| 324 | | 325 |Join Response | 326 |<----------------------------------------| 327 | | 328 |IEEE 802.11 WLAN Config. Request [ | 329 | IEEE 802.11 Add WLAN, | 330 | Alternate Tunnel Encapsulation ( | 331 | Tunnel Type, Tunnel Info Element) | 332 | ] | 333 |<----------------------------------------| 334 | | 335 | | 336 +-+-+-+-+-+-+ | 337 | Setup | | 338 | Alternate | | 339 | Tunnel | | 340 +-+-+-+-+-+-+ | 341 | | 342 |IEEE 802.11 WLAN Config. Response | 343 |---------------------------------------->| 344 | | 345 | | 346 +-+-+-+-+-+-+ | 347 | Tunnel | | 348 | Failure | | 349 +-+-+-+-+-+-+ | 350 |WTP Alternate Tunnel Failure Indication | 351 |(report failure (AR address(es))) | 352 |---------------------------------------->| 353 | | 354 +-+-+-+-+-+-+-+ | 355 | Tunnel | | 356 | Established | | 357 +-+-+-+-+-+-+-+ | 358 |WTP Alternate Tunnel Failure Indication | 359 |(report clearing failure) | 360 |---------------------------------------->| 361 | | 363 Figure 5: Setup of Alternate Tunnel 365 The above example describes how the alternate tunnel encapsulation 366 may be established. When the WTP joins the AC, it should indicate 367 its alternate tunnel encapsulation capability. The AC determines 368 whether an alternate tunnel configuration is required. If an 369 appropriate alternate tunnel type is selected, then the AC provides 370 the alternate tunnel encapsulation message element containing the 371 tunnel type and a tunnel-specific information element. The tunnel- 372 specific information element, for example, may contain information 373 like the IP address of the tunnel termination point. The WTP sets up 374 the alternate tunnel using the alternate tunnel encapsulation message 375 element. 377 Since AC can configure a WTP with more than one AR available for the 378 WTP to establish the data tunnel(s) for user traffic, it may be 379 useful for the WTP to communicate the selected AR. To enable this, 380 the IEEE 802.11 WLAN Configuration Response may contain the AR list 381 element containing the selected AR. 383 On detecting a tunnel failure, WTP SHALL forward data frames to the 384 AC and discard the frames. In addition, WTP may dissociate existing 385 clients and refuse association requests from new clients. Depending 386 on the implementation and deployment scenario, the AC may choose to 387 reconfigure the WLAN (on the WTP) to a local bridging mode or to 388 tunnel frames to the AC. When the WTP detects an alternate tunnel 389 failure, the WTP informs the AC using a message element, WTP 390 Alternate Tunnel Fail Indication (defined in this specification). It 391 MAY be carried in the CAPWAP Station Configuration Request message 392 which is defined in [RFC5415]. 394 The WTP also needs to notify the AC of which AR(s) are unavailable. 395 Particularly, in the VNO scenario, the AC of the WLAN service 396 provider needs to maintain the association of the AR addresses of the 397 VNOs and SSIDs, and provide this information to the WTP for the 398 purpose of load balancing or master-slave mode. 400 The message element has a status field that indicates whether the 401 message denotes reporting a failure or the clearing of the previously 402 reported failure. 404 For the case where AC is unreachable but the tunnel end point is 405 still reachable, the WTP behavior is up to the implementation. For 406 example, the WTP could either choose to tear down the alternate 407 tunnel or let the existing user's traffic continue to be tunneled. 409 3. CAPWAP Protocol Message Elements Extensions 411 3.1. Supported Alternate Tunnel Encapsulations 413 This message element is sent by a WTP to communicate its capability 414 to support alternate tunnel encapsulations. The message element 415 contains the following fields: 417 0 1 2 3 418 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 | Tunnel-Type1 | Tunnel-Type [2...N] 421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 Figure 6: Supported Alternate Tunnel Encapsulations 425 o Type: for Supported Alternate Tunnel Encapsulations 426 o Length: The length in bytes, two bytes for each Alternative tunnel 427 type that is included 428 o Tunnel-Type: This is identified by value defined in Section 3.2. 430 3.2. Alternate Tunnel Encapsulations Type 432 This message element is sent by the AC. This message element allows 433 the AC to select the alternate tunnel encapsulation. This message 434 element may be provided along with the IEEE 802.11 Add WLAN message 435 element. When the message element is present the following fields of 436 the IEEE 802.11 Add WLAN element SHALL be set as follows: MAC mode is 437 set to 0 (Local MAC) and Tunnel Mode is set to 0 (Local Bridging). 438 The message element contains the following fields: 440 0 1 2 3 441 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 | Tunnel-Type | Info Element Length | 444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 445 | Info Element 446 +-+-+-+-+-+-+-+-+-+ 448 Figure 7: Alternate Tunnel Encapsulations Type 450 o Type: for Alternate Tunnel Encapsulation Type 451 o Length: > 4 452 o Tunnel-Type: The tunnel type is specified by a 2 byte value. This 453 specification defines the values from zero (0) to six (6) as given 454 below. The remaining values are reserved for future use. 456 * 0: CAPWAP. This refers to a CAPWAP data channel described in 457 [RFC5415] and [RFC5416]. 458 * 1: L2TP. This refers to tunnel encapsulation described in 459 [RFC2661]. 460 * 2: L2TPv3. This refers to tunnel encapsulation described in 461 [RFC3931]. 462 * 3: IP-in-IP. This refers to tunnel encapsulation described in 463 [RFC2003]. 464 * 4: PMIPv6-UDP. This refers to the UDP tunneling encapsulation 465 described in [RFC5844]. 466 * 5: GRE. This refers to GRE tunnel encapsulation as described 467 in [RFC2784]. 468 * 6: GTPv1-U. This refers to GTPv1 user plane mode as described 469 in [TS29281]. 470 o Info Element: This field contains tunnel specific configuration 471 parameters to enable the WTP to setup the alternate tunnel. This 472 specification provides details for this elements for CAPWAP, 473 PMIPv6, and GRE. This specification reserves the tunnel type 474 values for the key tunnel types and defines the most common 475 message elements. It is anticipated that message elements for the 476 other protocols (like L2TPv3, etc.) will be defined in other 477 specifications in the future. 479 3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication 481 The Alternate Tunnel Failure Indication message element is sent by 482 the WTP to inform the AC about the status of the Alternate Tunnel. 483 It MAY be included in the CAPWAP Station Configuration Request 484 message. For the case where WTP establishes data tunnels with 485 multiple ARs (e.g., under VNO scenario), the WTP needs to notify the 486 AC of which AR(s) are unavailable. The message element contains the 487 following fields: 489 0 1 2 3 490 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 491 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 492 | WLAN ID | Status | Reserved | 493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 . Access Router Information Element . 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 497 Figure 8: IEEE 802.11 WTP Alternate Tunnel Failure Indication 499 o Type: for IEEE 802.11 WTP Alternate Tunnel Failure 500 Indication 501 o Length: > 4 502 o WLAN ID: An 8-bit value specifying the WLAN Identifier. The value 503 MUST be between one (1) and 16. 505 o Status: An 8-bit boolean indicating whether the radio failure is 506 being reported or cleared. A value of zero is used to clear the 507 event, while a value of one is used to report the event. 508 o Reserved: MUST be set to a value of 0 and MUST be ignored by the 509 receiver. 510 o Access Router Information Element: IPv4 address or IPv6 address of 511 the Access Router that terminates the alternate tunnel. The 512 Access Router Information Elements allow the WTP to notify the AC 513 of which AR(s) are unavailable. 515 4. Alternate Tunnel Types 517 4.1. CAPWAP based Alternate Tunnel 519 If the CAPWAP encapsulation is selected by the AC and configured by 520 the AC to the WTP, the Info Element field defined in Section 3.2 521 SHOULD contain the following information: 523 o Access Router Information: IPv4 address or IPv6 address of the 524 Access Router for the alternate tunnel. 525 o Tunnel DTLS Policy: The CAPWAP protocol allows optional protection 526 of data packets using DTLS. Use of data packet protection on a 527 WTP is not mandatory but determined by the associated AC policy 528 (This is consistent with the WTP behavior described in [RFC5415]). 529 o IEEE 802.11 Tagging Mode Policy: It is used to specify how the 530 CAPWAP data channel packet are to be tagged for QoS purposes (see 531 [RFC5416] for more details). 532 o CAPWAP Transport Protocol: The CAPWAP protocol supports both UDP 533 and UDP-Lite (see [RFC3828]). When run over IPv4, UDP is used for 534 the CAPWAP data channels. When run over IPv6, the CAPWAP data 535 channel may use either UDP or UDP-lite. 537 The message element structure for CAPWAP encapsulation is shown in 538 Figure 9: 540 0 1 2 3 541 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | Tunnel-Type=0 | Info Element Length | 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 . Access Router Information Element . 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 . Tunnel DTLS Policy Element . 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 549 . IEEE 802.11 Tagging Mode Policy Element . 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 . CAPWAP Transport Protocol Element . 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 554 Figure 9: Alternate Tunnel Encapsulation - CAPWAP 556 4.2. PMIPv6 based Alternate Tunnel 558 Proxy Mobile IPv6 (PMIPv6) (defined in [RFC5213]) based user plane 559 can also be used as alternate tunnel encapsulation between the WTP 560 and the AR. In this scenario, a WTP acts as the Mobile Access 561 Gateway (MAG) function that manages the mobility-related signaling 562 for a station that is attached to the WTP IEEE 802.11 radio access. 563 The Local Mobility Anchor (LMA) function is at the AR. If PMIPv6 UDP 564 encapsulation is selected by the AC and configured by the AC to a 565 WTP, the Info Element field defined in Section 3.2 SHOULD contain the 566 following information: 568 o Access Router (acts as LMA) Information: IPv4 or IPv6 address for 569 the alternate tunnel endpoint. 571 The message element structure for PMIPv6 encapsulation is shown in 572 Figure 10: 574 0 1 2 3 575 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 577 | Tunnel-Type=4 | Info Element Length | 578 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 579 . Access Router (LMA) Information Element . 580 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 582 Figure 10: Alternate Tunnel Encapsulation - PMIPv6 584 4.3. GRE based Alternate Tunnel 586 Generic Routing Encapsulation (defined in [RFC2784]) mode based user 587 plane can also be used as alternate tunnel encapsulation between the 588 WTP and the AR. In this scenario, a WTP and the access routers 589 represent the two end points of the GRE tunnel. If GRE encapsulation 590 is selected by the AC and configured by the AC to a WTP, the Info 591 Element field defined in Section 3.2 SHOULD contain the following 592 information: 594 o Access Router Information: IPv4 or IPv6 address for the alternate 595 tunnel endpoint. 596 o GRE Key Information: The Key field is intended to be used for 597 identifying an individual traffic flow within a tunnel [RFC2890]. 599 The message element structure for GRE encapsulation is shown in 600 Figure 11: 602 0 1 2 3 603 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 604 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 605 | Tunnel-Type=5 | Info Element Length | 606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 . Access Router Information Element . 608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 . GRE Key Element . 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 Figure 11: Alternate Tunnel Encapsulation - GRE 614 5. Alternate Tunnel Information Elements 616 This section defines the various elements described in Section 4.1, 617 Section 4.2, and Section 4.3. 619 These information elements can only be inluded in the Alternate 620 Tunnel Encapsulations Type message element, and the IEEE 802.11 WTP 621 Alternate Tunnel Failure Indication message element as their sub- 622 elements. 624 5.1. Access Router Information Elements 626 The Access Router Information Elements allow the AC to notify a WTP 627 of which AR(s) are available for establishing a data tunnel. The AR 628 information may be IPv4 address, or IPv6 address.This information 629 element SHOULD be contained whatever the tunnel type is. 631 The following are the Access Router Information Elements defined in 632 this specification. The AC can use one of them to notify the 633 destination information of the data tunnel to the WTP. The Elements 634 containing the AR IPv4 address MUST NOT be used if an IPv6 data 635 channel with IPv6 transport is used. 637 5.1.1. AR IPv4 List Element 639 This Element (see Figure 12) is used by the AC to configure a WTP 640 with the AR IPv4 address available for the WTP to establish the data 641 tunnel for user traffic. 643 0 1 2 3 644 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 645 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 646 | AR IPv4 Element Type | Length | 647 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 648 . AR IPv4 Address-1 . 649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 650 . AR IPv4 Address-2 . 651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 652 . AR IPv4 Address-N . 653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 Figure 12: AR IPv4 List Element 657 Type: 0 659 Length: This refers to the total length in octets of the element 660 excluding the Type and Length fields. 662 AR IPv4 Address: IPv4 address of the AR. At least one IPv4 address 663 SHALL be present. Multiple addresses may be provided for load 664 balancing or redundancy. 666 5.1.2. AR IPv6 List Element 668 This Element (see Figure 13) is used by the AC to configure a WTP 669 with the AR IPv6 address available for the WTP to establish the data 670 tunnel for user traffic. 672 0 1 2 3 673 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 | AR IPv6 Element Type | Length | 676 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 677 . AR IPv6 Address-1 . 678 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 679 . AR IPv6 Address-2 . 680 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 681 . AR IPv6 Address-N . 682 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 Figure 13: AR IPv6 List Element 686 Type: 1 688 Length: This refers to the total length in octets of the element 689 excluding the Type and Length fields. 691 AR IPv6 Address: IPv6 address of the AR. At least one IPv6 address 692 SHALL be present. Multiple addresses may be provided for load 693 balancing or redundancy. 695 5.2. Tunnel DTLS Policy Element 697 The AC distributes its DTLS usage policy for the CAPWAP data tunnel 698 between a WTP and the AR. There are multiple supported options, 699 represented by the bit field below as defined in AC Descriptor 700 message elements. The WTP MUST abide by one of the options for 701 tunneling user traffic with AR. The Tunnel DTLS Policy Element obeys 702 the definition in [RFC5415]. If there are more than one ARs 703 information provided by the AC for reliability reasons, the same 704 Tunnel DTLS Policy (see Figure 14) is generally applied for all 705 tunnels associated with the ARs. Otherwise, Tunnel DTLS Policy MUST 706 be bonding together with each of the ARs, then WTP will enforce the 707 independent tunnel DTLS policy for each tunnel with a specific AR. 709 0 1 2 3 710 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 712 |Tunnel DTLS Policy Element Type| Length | 713 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 714 | Reserved |A|D|C|R| 715 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 716 . AR Information (optional) . 717 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 719 Figure 14: Tunnel DTLS Policy Element 721 Type: 2 723 Length: This refers to the total length in octets of the element 724 excluding the Type and Length fields. 726 Reserved: A set of reserved bits for future use. All implementations 727 complying with this protocol MUST set to zero any bits that are 728 reserved in the version of the protocol supported by that 729 implementation. Receivers MUST ignore all bits not defined for the 730 version of the protocol they support. 732 A: If A bit is set, there is an AR information associated with the 733 DTLS policy. There may be an array of pairs binding DTLS policy 734 information and AR information contained in the Tunnel DTLS Policy 735 Element. Otherwise, the same Tunnel DTLS Policy (see Figure 14) is 736 generally applied for all tunnels associated with the ARs configured 737 by the AC. 739 D: DTLS-Enabled Data Channel Supported (see [RFC5415]). 741 C: Clear Text Data Channel Supported (see [RFC5415]). 743 R: A reserved bit for future use (see [RFC5415]). 745 5.3. IEEE 802.11 Tagging Mode Policy Element 747 In 802.11 networks, IEEE 802.11 Tagging Mode Policy Element is used 748 to specify how the WTP apply the QoS tagging policy when receiving 749 the packets from stations on a particular radio. When the WTP sends 750 out the packet to data channel to the AR(s), the packets have to be 751 tagged for QoS purposes (see [RFC5416]). 753 The IEEE 802.11 Tagging Mode Policy abides the IEEE 802.11 WTP 754 Quality of Service defined in Section 6.22 of [RFC5416]. 756 If there are more than one ARs information provided by the AC for 757 reliability reasons, the same IEEE 802.11 Tagging Mode Policy (see 758 Figure 15) is generally applied for all tunnels associated with the 759 ARs. Otherwise, IEEE 802.11 Tagging Mode Policy MUST be bonding 760 together with each of the ARs, then WTP will enforce the independent 761 tunnel IEEE 802.11 Tagging Mode Policy for each tunnel with a 762 specific AR. 764 0 1 2 3 765 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 766 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 767 | Tagging Mode Policy Ele. Type | Length | 768 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 769 | Reserved |A|P|Q|D|O|I| 770 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 771 . AR Information (optional) . 772 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 774 Figure 15: IEEE 802.11 Tagging Mode Policy Element 776 Type: 3 778 Length: This refers to the total length in octets of the element 779 excluding the Type and Length fields. 781 Reserved: A set of reserved bits for future use. 783 A: If A bit is set, there is an AR information associated with the 784 Tagging Mode policy. There may be an array of pairs binding Tagging 785 Mode policy information and AR information contained in the Tagging 786 Mode Policy Element. Otherwise, the same Tagging Mode Policy (see 787 Figure 15) is generally applied for all tunnels associated with the 788 ARs configured by the AC. 790 P: When set, the WTP is to employ the 802.1p QoS mechanism (see 791 [RFC5416]). 793 Q: When the 'P' bit is set, the 'Q' bit is used by the AC to 794 communicate to the WTP how 802.1p QoS is to be enforced. (see 795 [RFC5416]). 797 D: When set, the WTP is to employ the DSCP QoS mechanism (see 798 [RFC5416]). 800 O: When the 'D' bit is set, the 'O' bit is used by the AC to 801 communicate to the WTP how DSCP QoS is to be enforced on the outer 802 (tunneled) header (see [RFC5416]). 804 I: When the 'D' bit is set, the 'I' bit is used by the AC to 805 communicate to the WTP how DSCP QoS is to be enforced on the 806 station's packet (inner) header (see [RFC5416]). 808 5.4. CAPWAP Transport Protocol Element 810 The CAPWAP data tunnel supports both UDP and UDP-Lite (see 811 [RFC3828]). When run over IPv4, UDP is used for the CAPWAP data 812 channels. When run over IPv6, the CAPWAP data channel may use either 813 UDP or UDP-lite. The AC specifies and configure the WTP for which 814 transport protocol is to be used for the CAPWAP data tunnel. 816 The CAPWAP Transport Protocol Element abides the definition in 817 Section 4.6.14 of [RFC5415]. 819 0 1 2 3 820 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 821 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 822 | Type=4 | Length | 823 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 824 | Transport | 825 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 827 Figure 16: CAPWAP Transport Protocol Element 829 Type: 4 831 Length: 1 833 Transport: The transport to use for the CAPWAP Data channel. The 834 following enumerated values are supported: 836 1 - UDP-Lite: The UDP-Lite transport protocol is to be used for the 837 CAPWAP Data channel. Note that this option MUST NOT be used if the 838 CAPWAP Control channel is being used over IPv4 and AR address is IPv4 839 contained in the AR Information Element. 841 2 - UDP: The UDP transport protocol is to be used for the CAPWAP Data 842 channel. 844 5.5. GRE Key Element 846 If a WTP receives the GRE Key Element in the Alternate Tunnel 847 Encapsulation message element for GRE selection, the WTP MUST insert 848 the GRE Key to the encapsulation packet (see [RFC2890]). An AR 849 acting as decapsulating tunnel endpoint identifies packets belonging 850 to a traffic flow based on the Key value. 852 The GRE Key Element field contains a four octet number defined in 853 [RFC2890]. 855 0 1 2 3 856 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 857 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 858 | GRE Key Element Type | Length | 859 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 860 | GRE Key | 861 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 Figure 17: GRE Key Element 865 Type: 5 867 Length: This refers to the total length in octets of the element 868 excluding the Type and Length fields. 870 GRE Key: The Key field contains a four octet number which is inserted 871 by the WTP according to [RFC2890]. 873 5.6. IPv6 MTU Element 875 If AC has chosen a tunneling mechanism based on IPv6, it SHOULD 876 support the minimum IPv6 MTU requirements [RFC2460]. This issue is 877 described in [I-D.ietf-intarea-tunnels]. AC SHOULD inform the WTP 878 about the IPv6 MTU information in the "Tunnel Info Element" field. 880 0 1 2 3 881 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 883 | IPv6 MTU Element Type | Length | 884 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 885 | Minimum IPv6 MTU | Reserved | 886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 Figure 18: IPv6 MTU Element 890 Type: 6 892 Length: This refers to the total length in octets of the element 893 excluding the Type and Length fields. 895 Minimum IPv6 MTU: The field contains a two octet number indicate the 896 minimum IPv6 MTU in the tunnel. 898 6. IANA Considerations 900 This document requires the following IANA considerations. 902 o . This specification defines the Supported Alternate 903 Tunnel Encapsulations Type message element in Section 3.1. This 904 elements needs to be registered in the existing CAPWAP Message 905 Element Type registry, defined in [RFC5415]. The Type value for 906 this element needs to be between 1 and 1023 (see Section 15.7 in 907 [RFC5415]). 908 o . This specification defines the Alternate Tunnel 909 Encapsulations Type message element in Section 3.2. This element 910 needs to be registered in the existing CAPWAP Message Element Type 911 registry, defined in [RFC5415]. The Type value for this element 912 needs to be between 1 and 1023. 913 o . This specification defines the IEEE 802.11 WTP 914 Alternate Tunnel Failure Indication message element in 915 Section 3.3. This element needs to be registered in the existing 916 CAPWAP Message Element Type registry, defined in [RFC5415]. The 917 Type value for this element needs to be between 1024 and 2047. 918 o Alternate Tunnel-Types Registry: This specification defines the 919 Alternate Tunnel Encapsulations Type message element. This 920 element contains a field Tunnel-Type. The namespace for the field 921 is 16 bits (0-65535). This specification defines values, zero (0) 922 through six (6) and can be found in Section 3.2. Future 923 allocations of values in this name space are to be assigned by 924 IANA using the "Specification Required" policy. IANA needs to 925 create a registry called CAPWAP Alternate Tunnel-Types. The 926 registry format is given below. 928 Tunnel-Type Type Value Reference 929 CAPWAP 0 [RFC5415],[RFC5416] 930 L2TP 1 [RFC2661] 931 L2TPv3 2 [RFC3931] 932 IP-IP 3 [RFC2003] 933 PMIPv6-UDP 4 [RFC5844] 934 GRE 5 [RFC2784] 935 GTPv1-U 6 [3GPP TS 29.281] 937 o Alternate Tunnel Sub-elements Registry: This specification defines 938 the Alternate Tunnel Sub-elements. Currently, these information 939 elements can only be inluded in the Alternate Tunnel 940 Encapsulations Type message element, and the IEEE 802.11 WTP 941 Alternate Tunnel Failure Indication message element as their sub- 942 elements. These information elements contains a Type field. The 943 namespace for the field is 16 bits (0-65535). This specification 944 defines values, zero (0) through six (6) in Section 5. This 945 namespace is managed by IANA and assignments require an Expert 946 Review. 948 Type Type Value 949 AR IPv4 List 0 950 AR IPv6 List 1 951 Tunnel DTLS Policy 2 952 IEEE 802.11 Tagging Mode Policy 3 953 CAPWAP Transport Protocol 4 954 GRE Key 5 955 IPv6 MTU 6 957 7. Security Considerations 959 This document introduces three new CAPWAP WTP message elements. 960 These elements are transported within CAPWAP Control messages as the 961 existing message elements. Therefore, this document does not 962 introduce any new security risks to the control plane compared to 963 [RFC5415] and [RFC5416]. In the data plane, if the encapsulation 964 type selected itself is not secured, it is suggested to protect the 965 tunnel by using known secure methods, such as IPSec. 967 8. Contributors 969 The authors would like to thank Andreas Schultz, Hong Liu, Yifan 970 Chen, Chunju Shao, Li Xue, Jianjie You, Jin Li, Joe Touch, Alexey 971 Melnikov, Kathleen Moriarty, Mirja Kuehlewind, Catherine Meadows, and 972 Paul Kyzivat for their valuable comments. 974 9. References 976 9.1. Normative References 978 [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, 979 DOI 10.17487/RFC2003, October 1996, 980 . 982 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 983 Requirement Levels", BCP 14, RFC 2119, 984 DOI 10.17487/RFC2119, March 1997, 985 . 987 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 988 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 989 December 1998, . 991 [RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, 992 G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"", 993 RFC 2661, DOI 10.17487/RFC2661, August 1999, 994 . 996 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 997 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 998 DOI 10.17487/RFC2784, March 2000, 999 . 1001 [RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE", 1002 RFC 2890, DOI 10.17487/RFC2890, September 2000, 1003 . 1005 [RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., Ed., 1006 and G. Fairhurst, Ed., "The Lightweight User Datagram 1007 Protocol (UDP-Lite)", RFC 3828, DOI 10.17487/RFC3828, July 1008 2004, . 1010 [RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed., 1011 "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", 1012 RFC 3931, DOI 10.17487/RFC3931, March 2005, 1013 . 1015 [RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, 1016 Ed., "Control And Provisioning of Wireless Access Points 1017 (CAPWAP) Protocol Specification", RFC 5415, 1018 DOI 10.17487/RFC5415, March 2009, 1019 . 1021 [RFC5416] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, 1022 Ed., "Control and Provisioning of Wireless Access Points 1023 (CAPWAP) Protocol Binding for IEEE 802.11", RFC 5416, 1024 DOI 10.17487/RFC5416, March 2009, 1025 . 1027 9.2. Informative References 1029 [I-D.ietf-intarea-tunnels] 1030 Touch, J. and M. Townsley, "IP Tunnels in the Internet 1031 Architecture", draft-ietf-intarea-tunnels-05 (work in 1032 progress), March 2017. 1034 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1035 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1036 RFC 5213, DOI 10.17487/RFC5213, August 2008, 1037 . 1039 [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy 1040 Mobile IPv6", RFC 5844, DOI 10.17487/RFC5844, May 2010, 1041 . 1043 [TS29281] "3rd Generation Partnership Project; Technical 1044 Specification Group Core Network and Terminals; General 1045 Packet Radio System (GPRS) Tunnelling Protocol User Plane 1046 (GTPv1-U)", 2016. 1048 Authors' Addresses 1050 Rong Zhang 1051 China Telecom 1052 No.109 Zhongshandadao avenue 1053 Guangzhou 510630 1054 China 1056 Email: zhangr@gsta.com 1058 Rajesh S. Pazhyannur 1059 Cisco 1060 170 West Tasman Drive 1061 San Jose, CA 95134 1062 USA 1064 Email: rpazhyan@cisco.com 1066 Sri Gundavelli 1067 Cisco 1068 170 West Tasman Drive 1069 San Jose, CA 95134 1070 USA 1072 Email: sgundave@cisco.com 1074 Zhen Cao 1075 Huawei 1076 Xinxi Rd. 3 1077 Beijing 100085 1078 China 1080 Email: zhencao.ietf@gmail.com 1081 Hui Deng 1082 Huawei 1083 Xinxi Rd. 3 1084 Beijing 100085 1085 China 1087 Email: denghui02@gmail.com 1089 Zongpeng Du 1090 Huawei 1091 No.156 Beiqing Rd. Z-park, HaiDian District 1092 Beijing 100095 1093 China 1095 Email: duzongpeng@huawei.com