idnits 2.17.1 draft-ietf-l2tpext-pwe3-atm-04.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 18. -- Found old boilerplate from RFC 3978, Section 5.5 on line 1182. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1159. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1166. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1172. ** This document has an original RFC 3978 Section 5.4 Copyright Line, instead of the newer IETF Trust Copyright according to RFC 4748. ** This document has an original RFC 3978 Section 5.5 Disclaimer, instead of the newer disclaimer which includes the IETF Trust according to RFC 4748. 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 : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC2119]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: The "ATM Maximum Cells Concatenated AVP", Attribute type 86, indicates that the egress LCCE node can process a single PDU with concatenated cells upto a specified number of cells. An LCCE node transmitting concatenated cells on this PW MUST not exceed the maximum number of cells as specified in this AVP. This AVP is applicable only to ATM Cell-Relay PW Types (VCC, VPC, Port Cell-Relay). This Attribute value may not be same in both directions of the specific PW. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 2006) is 6674 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) == Outdated reference: A later version (-11) exists of draft-ietf-pwe3-atm-encap-10 -- Obsolete informational reference (is this intentional?): RFC 2434 (Obsoleted by RFC 5226) Summary: 4 errors (**), 0 flaws (~~), 3 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Sanjeev Singh 3 Internet-Draft W. Mark Townsley 4 Category: Standards Track Carlos Pignataro 5 Expiration Date: July 2006 Cisco Systems 7 January 2006 9 ATM over L2TPv3 11 draft-ietf-l2tpext-pwe3-atm-04.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as Internet- 23 Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/1id-abstracts.html 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html 36 Abstract 38 The Layer 2 Tunneling Protocol, Version 3, (L2TPv3) defines an 39 extensible tunneling protocol to transport layer 2 services over IP 40 network. This document describes the specifics of how to use the L2TP 41 control plane for Asynchronous Transfer Mode (ATM) Pseudowires and 42 provides guidelines for transporting various ATM services over an IP 43 network. 45 Contents 47 Status of this Memo.......................................... 1 49 1. Introduction.............................................. 3 50 1.1 Abbreviations......................................... 3 52 2. Control Connection Establishment.......................... 4 54 3. Session Establishment and ATM Circuit Status Notification. 4 55 3.1 L2TPv3 Session Establishment.......................... 4 56 3.2 L2TPv3 Session Teardown............................... 6 57 3.3 L2TPv3 Session Maintenance............................ 6 59 4. Encapsulation............................................. 7 60 4.1 ATM-Specific Sublayer................................. 7 61 4.2 Sequencing............................................ 9 63 5. ATM Transport............................................. 9 64 5.1 ATM AAL5-SDU Mode..................................... 10 65 5.2 ATM Cell Mode......................................... 10 66 5.2.1 ATM VCC Cell-Relay Service....................... 11 67 5.2.2 ATM VPC Cell-Relay Service....................... 12 68 5.2.3 ATM Port Cell-Relay Service...................... 12 69 5.3 OAM Cell Support...................................... 12 70 5.3.1 VCC switching.................................... 12 71 5.3.1 VPC switching.................................... 13 73 6. ATM Maximum Concatenated Cells AVP........................ 13 75 7. OAM Emulation Required AVP................................ 13 77 8. ATM defects mapping and status notification............... 14 78 8.1 ATM Alarm Status AVP.................................. 14 80 9. Applicability Statement................................... 15 81 9.1 ATM AAL5-SDU Mode..................................... 16 82 9.2 ATM Cell-Relay Mode................................... 18 84 10. Congestion Control....................................... 19 86 11. Security Considerations.................................. 20 88 12. IANA Considerations...................................... 21 89 12.1 L2-Specific Sublayer Type............................ 21 90 12.2 Control Message Attribute Value Pairs (AVPs)......... 21 91 12.3 Result Code AVP Values............................... 21 92 12.4 ATM Alarm Status AVP Values.......................... 22 93 12.5 ATM-Specific Sublayer bits........................... 22 95 13. Acknowledgments.......................................... 23 97 14. References............................................... 23 98 14.1 Normative References................................. 23 99 14.2 Informative References............................... 23 101 15. Authors' Addresses....................................... 25 103 Specification of Requirements 105 In this document, several words are used to signify the requirements 106 of the specification. These words are often capitalized. The key 107 words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", 108 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document 109 are to be interpreted as described in [RFC2119]. 111 1. Introduction 113 This document describes the specifics of how to use the L2TP for ATM 114 Pseudowires, including encapsulation, carrying various ATM services, 115 such as, AAL5 SDU, ATM VCC/VPC/Port cell-relay over L2TP, and mapping 116 ATM defects to L2TP Set Link Info (SLI) message to notify the peer 117 LCCE. 119 Any ATM specific AVPs or other L2TP constructs for ATM Pseudowire 120 (ATMPW) support are defined here as well. Support for ATM Switched 121 Virtual Path/Connection (SVP/SVC) and Soft Permanent Virtual 122 Path/Connection (SPVP/SPVC) are outside the scope of this document. 124 The reader is expected to be very familiar with the terminology and 125 protocol constructs defined in [RFC3931]. 127 1.1 Abbreviations 129 AIS Alarm Indication Signal 130 ATMPW ATM Pseudowire 131 AVP Attribute Value Pair 132 CC Continuity Check OAM Cell 133 CE Customer Edge 134 HEC Header Error Control 135 LAC L2TP Access Concentrator (See [RFC3931]) 136 LCCE L2TP control connection endpoint (See [RFC3931]) 137 MSB Most Significant Byte 138 OAM Operation, Administration, and Management 139 PE Provider Edge 140 PSN Packet Service Network 141 PWE3 Pseudowire Edge-to-edge emulation 142 RDI Remote Defect Indicator 143 SDU Service Data Unit 144 SLI Set Link Info, an L2TP control message 145 SVC Switched Virtual Connection 146 SVP Switched Virtual Path 147 SPVC Soft Permanent Virtual Connection 148 SPVP Soft Permanent Virtual Path 149 VC Virtual Circuit 150 VCC Virtual Channel Connection 151 VCI Virtual Channel Identifier 152 VPC Virtual Path Connection 153 VPI Virtual Path Identifier 155 2. Control Connection Establishment 157 To emulate, ATM Pseudowires using L2TP, an L2TP Control Connection as 158 described in Section 3.3 of [RFC3931] MUST be established. 160 The SCCRQ and corresponding SCCRP MUST include the supported ATM 161 Pseudowire Types (See Section 3.1), in the Pseudowire Capabilities 162 List as defined in Section 5.4.3 of [RFC3931]. This identifies the 163 control connection as able to establish L2TP sessions in support of 164 the ATM Pseudowires. 166 An LCCE MUST be able to uniquely identify itself in the SCCRQ and 167 SCCRP messages via a globally unique value. By default, this is 168 advertised via the structured Router ID AVP [RFC3931], though the 169 unstructured Hostname AVP [RFC3931] MAY be used to identify LCCEs via 170 this value. 172 3. Session Establishment and ATM Circuit Status Notification 174 This section describes how L2TP ATMPWs or sessions are established 175 between two LCCEs. This includes what will happen when an ATM Circuit 176 (e.g. AAL5 PVC) is created, deleted or changes state when circuit 177 state is in alarm. 179 3.1 L2TPv3 Session Establishment 181 ATM Circuit (e.g. an AAL5 PVC) creation triggers establishment of a 182 L2TP session using three-way handshake described in Section 3.4.1 of 183 [RFC3931]. An LCCE MAY initiate the session immediately upon ATM 184 circuit creation, or wait until the Circuit state transitions to 185 ACTIVE before attempting to establish a session for the ATM circuit. 186 It MAY be preferred to wait until Circuit status transitions to 187 ACTIVE in order to avoid wasting L2TP resources. 189 The Circuit Status AVP (see Section 8) MUST be present in the ICRQ 190 and ICRP messages, and MAY be present in the SLI message for ATMPWs. 192 The following figure shows how L2TP messages are exchanged to setup 193 an ATMPWs after ATM Circuit (e.g. an AAL5 PVC) becomes ACTIVE. 195 LCCE (LAC) A LCCE (LAC) B 196 ------------------ -------------------- 198 ATM Ckt Provisioned 199 ATM Ckt Provisioned 200 ATM Ckt ACTIVE 201 ICRQ (status = 0x03) ----> 202 ATM Ckt ACTIVE 203 <----- ICRP (status = 0x03) 204 L2TP session established 205 OK to send data into PW 207 ICCN -----> 208 L2TP session established 209 OK to send data into PW 211 The following signaling elements are required for the ATMPW 212 establishment. 214 a. Pseudowire Type: One of the supported ATM related PW Types should 215 be present in the Pseudowire Type AVP of [RFC3931]. 217 0x0002 ATM AAL5 SDU VCC transport 218 0x0003 ATM Cell transport Port Mode 219 0x0009 ATM Cell transport VCC Mode 220 0x000A ATM Cell transport VPC Mode 222 The above Cell-Relay modes can also signal the ATM Cell Concatenation 223 AVP as described in Section 6. 225 b. Remote End ID: Each PW is associated with a Remote End ID 226 akin to the VC-ID in [PWE3ATM]. Two LCCEs of a PW would have the 227 same Remote End ID and its format is described in Section 5.4.4 228 of [RFC3931]. 230 This Remote End ID AVP MUST be present in the ICRQ in order for 231 the remote LCCE to associate the session to the ATM Circuit. The 232 Remote End Identifier AVP defined in [RFC3931] is of opaque form, 233 though ATMPW implementations MAY simply use a four-octet value 234 that is known to both LCCEs (either by direct configuration, or 235 some other means). The exact method of how this value is 236 configured, retrieved, discovered, or otherwise determined at 237 each LCCE is outside the scope of this document. 239 As with the ICRQ, the ICRP is sent only after the ATM Circuit 240 transitions to ACTIVE. If LCCE B had not been provisioned yet for the 241 ATM Circuit identified in the ICRQ, a CDN would have been immediately 242 returned indicating that the circuit was either not provisioned or is 243 not available at this LCCE. LCCE A should then exhibit a periodic 244 retry mechanism. The period and maximum number of retries MUST be 245 configurable. 247 An Implementation MAY send an ICRQ or ICRP before a PVC is ACTIVE, as 248 long as the Circuit Status AVP reflects that the ATM Circuit is 249 INACTIVE and an SLI is sent when the ATM Circuit becomes ACTIVE (see 250 Section 8). 252 The ICCN is the final stage in the session establishment. It confirms 253 the receipt of the ICRP with acceptable parameters to allow 254 bidirectional traffic. 256 3.2 L2TPv3 Session Teardown 258 When an ATM Circuit is unprovisioned (deleted) at either LCCE, the 259 associated L2TP session MUST be torn down via the CDN message defined 260 in Section 3.4.3 of [RFC3931]. 262 3.3 L2TPv3 Session Maintenance 264 All sessions established by a given control connection utilize the 265 L2TP Hello facility defined in Section 4.4 of [RFC3931] for session 266 keepalive. This gives all sessions basic dead peer and path detection 267 between LCCEs. 269 If the control channel utilizing the Hello message is not in-band 270 with data traffic over PSN, then other method MAY be used to detect 271 the Session failure and it is left for further study. 273 ATMPWs over L2TP use the Set Link Info (SLI) control message as 274 defined in [RFC3931] to signal ATM Circuit Status between LCCEs after 275 initial session establishment. This includes ACTIVE or INACTIVE 276 notifications of the ATM Circuit, or any other parameters that may 277 need to be shared between the LCCEs in order to provide proper PW 278 emulation. 280 The SLI message MUST be sent whenever there is a status change which 281 may be reported by any values identified in the Circuit Status AVP. 282 The only exception to this are the initial ICRQ, ICRP and CDN 283 messages which establish and teardown the L2TP session itself when 284 ATM circuit is created or deleted. The SLI message may be sent from 285 either LCCE at any time after the first ICRQ is sent (and perhaps 286 before an ICRP is received, requiring the peer to perform a reverse 287 Session ID lookup). 289 The other application of the SLI message is to map the ATM OAM or 290 physical layer alarms into Circuit Status AVP as described in Section 291 8. 293 4. Encapsulation 295 This section describes the general encapsulation format for ATM 296 services over L2TP. 298 Figure 1: General format for ATM encapsulation over L2TPv3 over IP 300 0 1 2 3 301 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 1 302 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 303 | PSN Transport Header | 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 | Session Header | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 | ATM-Specific Sublayer | 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 | | 310 | ATM Service Payload | 311 | | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 314 The PSN Transport header is specific to IP and its underlying 315 transport header. This header is used to transport the encapsulated 316 ATM payload through the IP network. 318 The Session Header is a non-zero 32-bit session ID with optional 319 cookies up to 64-bits. This Session ID is exchanged during session 320 setup. 322 The ATM Specific Sublayer is REQUIRED for AAL5 SDU mode and OPTIONAL 323 for ATM Cell mode. Please refer to Section 4.1 for more details. 325 4.1 ATM-Specific Sublayer 327 This section defines a new ATM-specific sublayer as, an alternative 328 to default L2-Specific Sublayer as mentioned in Section 4.6 of 329 [RFC3931]. Four new flag bits (T,G,C,U) are defined which concur 330 with Section 8.2 of [PWE3ATM]. 332 Figure 2: ATM-Specific Sublayer Format 333 0 1 2 3 334 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 1 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 |x|S|B|E|T|G|C|U| Sequence Number | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 Definition of these four bits are as per Section 8.2 of [PWE3ATM] and 340 also included here for reference. 342 * S bit 344 Definition of this bit is as per Section 4.6 of [RFC3931]. 346 * B and E bits 348 Definition of these bits as per Section 5.5 of [L2TPFRAG] 350 These bits are reserved and MUST be set to 0 upon transmission 351 and ignored upon reception, unless otherwise, these bits are 352 used as per [L2TPFRAG]. 354 * T (Transport type) bit 356 Bit (T) of the control word indicates whether the packet 357 contains an ATM admin cell or an AAL5 payload. If T = 1, the 358 packet contains an ATM admin cell, encapsulated according to 359 the VCC cell relay encapsulation of Section 5.2. 360 If not set, the PDU contains an AAL5 payload. The ability to 361 transport an ATM cell in the AAL5 SDU mode is intended to 362 provide a means of enabling administrative functionality over 363 the AAL5 VCC (though it does not endeavor to preserve user-cell 364 and admin-cell arrival/transport ordering). 366 * G (EFCI) Bit 368 The ingress LCCE device SHOULD set this bit to 1 if the EFCI bit 369 of the final cell of the incoming AAL5 payload is set to 1, or 370 if the EFCI bit of the single ATM cell to be transported in 371 the packet is set to 1. Otherwise this bit SHOULD be set to 372 0. The egress LCCE device SHOULD set the EFCI bit of all the 373 outgoing cells that transport the AAL5 payload to the value 374 contained in this field. 376 * C (CLP) Bit 378 The ingress LCCE device SHOULD set this bit to 1 if the CLP bit 379 of any of the incoming ATM cells of the AAL5 payload are set 380 to 1, or if the CLP bit of the single ATM cell that is to be 381 transported in the packet is set to 1. Otherwise this bit 382 SHOULD be set to 0. The egress LCCE device SHOULD set the CLP 383 bit of all outgoing cells that transport the AAL5 CPCS-PDU to 384 the value contained in this field. 386 * U (Command/Response) Bit 388 When FRF.8.1 Frame Relay / ATM PVC Service Interworking (see 389 [FRF8.1]) traffic is being transported, the CPCS-UU Least 390 Significant Bit (LSB) of the AAL5 CPCS-PDU may contain the 391 Frame Relay C/R bit. 392 The ingress LCCE device SHOULD copy this bit to the U bit of 393 the control word. The egress LCCE device SHOULD copy the 394 U bit to the CPCS-UU Least Significant Bit (LSB) of the AAL5 395 payload. 397 The Sequence Number fields are described in Section 4.3 399 In case of a reassembly timeout, the encapsulating LCCE should 400 discard all component cells of the AAL5 frame. 402 An additional enumeration is added to the L2-Specific Sublayer AVP 403 to identify the ATM-Specific Sublayer: 405 0 - There is no L2-Specific Sublayer present. 406 1 - The Default L2-Specific Sublayer (defined in Section 4.6 407 of [RFC3931]) is used. 408 2 - The ATM-Specific Sublayer is used. 410 The first two values are already defined in the L2TPv3 base 411 specification [RFC3931]. 413 4.2 Sequencing 415 Data Packet Sequencing MAY be enabled for ATMPWs. The sequencing 416 mechanisms described in [RFC3931] MUST be used to signal sequencing 417 support. ATMPWs over L2TPv3 MUST request the presence of the ATM- 418 Specific Sublayer when sequencing is enabled, and MAY request its 419 presence at all times. 421 5. ATM Transport 423 There are two encapsulations supported for ATM transport as described 424 below. 426 ATM Specific Sublayer is prepended to AAL5-SDU. The other Cell-mode 427 encapsulation consists of the OPTIONAL ATM-Specific Sublayer and 4- 428 byte ATM Cell Header and 48-byte ATM Cell-payload. 430 5.1 ATM AAL5-SDU Mode 432 In this mode each AAL5 VC is mapped to an L2TP session. Ingress LCCE 433 reassembles AAL5 CPCS-SDU without AAL5 trailer and any padding bytes. 434 Incoming EFCI, CLP and C/R (if present) are carried in ATM Specific 435 sublayer across ATMPWs to egress LCCE. The processing of these bits 436 on ingress and egress LCCEs is defined in Section 4.1. 438 0 1 2 3 439 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 1 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 441 |x|S|x|x|T|G|C|U| Sequence Number | 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 | | 444 | | 445 | AAL5 CPCS-SDU | 446 | | 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 449 If ingress LCCE determines that an encapsulated AAL5 SDU exceeds the 450 MTU size of the L2TPv3 session, then AAL5 SDU may be fragmented as 451 per [L2TPFRAG] or underneath Transport layer (IP, etc). F5 OAM cells 452 that arrive during the reassembly of an AAL5 SDU are sent immediately 453 on the PW followed by the AAL5 SDU payload. In this case OAM cell's 454 relative order with respect to user data cells is not maintained. 456 Performance Monitoring OAM, as specified in ITU-T 610 [I610-1], 457 [I610-2], [I610-3] and security OAM cells as specified in [ATMSEC], 458 should not be used in combination with AAL5 SDU mode. These cells MAY 459 be dropped at ingress LCCE because cell sequence integrity is not 460 maintained. 462 The Pseudowire Type AVP defined in Section 5.4.4 of [RFC3931], 463 Attribute Type 68, MUST be present in the ICRQ messages and MUST 464 include the ATM AAL5 SDU VCC transport PW Type of 0x0002. 466 5.2 ATM Cell Mode 468 In this mode, ATM cells skip the reassembly process at ingress LCCE. 469 These cells are transported over an L2TP session, either as a single 470 Cell or as concatenated cells, into a single packet. Each ATM Cell 471 consists of 4 byte ATM cell header and 48-byte ATM Cell-payload, HEC 472 is not included. 474 In ATM Cell Mode encapsulation, ATM-Specific Sublayer is OPTIONAL. 475 It can be included, if sequencing support is required. It is left to 476 the implementation to choose to signal Default L2-Specific Sublayer 477 or ATM-Specific Sublayer. 479 0 1 2 3 480 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 1 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 482 |x|S|x|x|x|x|x|x| Sequence Number (Optional) | 483 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 484 | VPI | VCI |PTI |C| 485 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 486 | | 487 | ATM Cell Payload (48-bytes) | 488 | | 489 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 490 " 491 " 492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 493 | VPI | VCI |PTI |C| 494 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 495 | | 496 | ATM Cell Payload (48-bytes) | 497 | | 498 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 In the simplest case, this encapsulation can be used to transmit 501 a single ATM cell per Pseudowire PDU. However, in order to 502 provide better Pseudowire bandwidth efficiency, several ATM cells 503 may be optionally encapsulated into single Pseudowire PDU. 505 The maximum number of concatenated cells in a packet is limited by 506 the MTU size of the session and also by the ability of egress 507 LCCE to process them. For more details about ATM Maximum 508 Concatenated cells, please refer to Section 6. 510 5.2.1 ATM VCC Cell-Relay Service 512 A VCC cell relay service may be provided by mapping an ATM Virtual 513 Channel Connection to a single Pseudowire using cell mode 514 encapsulation as defined in Section 5.2. 516 An LCCE may map one or more VCCs to a single PW. However, a service 517 provider may wish to provision a single VCC to a PW in order to 518 satify QOS or restoration requirement. 520 The Pseudowire Type AVP defined in Section 5.4.4 of [RFC3931], 521 Attribute Type 68, MUST be present in the ICRQ messages and MUST 522 include the ATM Cell transport VCC mode PW Type of 0x0009. 524 5.2.2 ATM VPC Cell-Relay Service 526 A Virtual Path Connection cell relay service may be provided by 527 mapping an ATM Virtual Path Connection to single Pseudowire using 528 cell mode encapsulation as defined in Section 5.2. 530 An LCCE may map one or more VPCs to a single Pseudowire. 532 The Pseudowire Type AVP defined in Section 5.4.4 of [RFC3931], 533 Attribute Type 68, MUST be present in the ICRQ messages and MUST 534 include the ATM Cell transport VPC mode PW Type of 0x000A. 536 5.2.3 ATM Port Cell-Relay Service 538 ATM port cell relay service allows an ATM port to be connected to 539 only another ATM port. All ATM cells that are received at the 540 ingress ATM port on the LCCE, are encapsulated as per Section 5.2, 541 into Pseudowire PDU and sent to peer LCCE. 543 Each LCCE MUST discard any idle/unassigned cells received on an ATM 544 port associated with ATMPWs. 546 The Pseudowire Type AVP defined in Section 5.4.4 of [RFC3931], 547 Attribute Type 68, MUST be present in the ICRQ messages and MUST 548 include the ATM Cell transport Port mode PW Type of 0x0003. 550 5.3 OAM Cell Support 552 The OAM cells are defined in [I610-1], [I610-2], [I610-3] and 553 [ATMSEC] can be categorized as: 555 a. Fault Management 556 b. Performance monitoring and reporting 557 c. Activation/deactivation 558 d. System Management (e.g. security OAM cells). 560 OAM Cells are always encapsulated using cell mode encapsulation, 561 regardless of the encapsulation format used for user data. 563 5.3.1 VCC switching 565 The LCCEs SHOULD be able to pass the F5 segment and end-to-end Fault 566 Management, Resource Management (RM cells), Performance Management, 567 Activation/deactivation and System Management OAM cells. 569 F4 OAM cells are inserted or extracted at the VP link termination. 570 These OAM cells are not seen at the VC link termination and are 571 therefore not sent across the PW. 573 5.3.1 VPC switching 575 The LCCEs MUST be able to pass the F4 segment and end-to-end Fault 576 Management, Resource Management (RM cells), Performance Management, 577 Activation/deactivation and System Management OAM cells transparently 578 according to [I610-1]. 580 F5 OAM cells are not inserted or extracted at the VP cross-connect. 581 The LCCEs MUST be able to pass the F5 OAM cells transparently across 582 the PW. 584 6. ATM Maximum Concatenated Cells AVP 586 The "ATM Maximum Cells Concatenated AVP", Attribute type 86, 587 indicates that the egress LCCE node can process a single PDU with 588 concatenated cells upto a specified number of cells. An LCCE 589 node transmitting concatenated cells on this PW MUST not exceed 590 the maximum number of cells as specified in this AVP. This AVP 591 is applicable only to ATM Cell-Relay PW Types (VCC, VPC, Port 592 Cell-Relay). This Attribute value may not be same in both 593 directions of the specific PW. 595 The Attribute Value field for this AVP has the following format: 597 0 1 598 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 | ATM Maximum Concatenated Cells| 601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 603 This AVP MAY be hidden (the H bit MAY be 0 or 1). The M bit for this 604 AVP MAY be set to 0, but MAY vary (see Section 5.2 of [RFC3931]). 605 The length (before hiding) of this AVP is 8. 607 This AVP is sent in an ICRQ, ICRP during session negotiation or via 608 SLI control messages when LCCE changes the maximum number of 609 Concatenated Cells configuration for a given ATM cell-relay Circuit. 611 This AVP is OPTIONAL. If egress LCCE is configured with maximum 612 number of cells to be concatenated by ingress LCEE, it should signal 613 to ingress LCCE. 615 7. OAM Emulation Required AVP 617 An "OAM Emulation Required AVP", Attribute type 87, MAY be needed to 618 signal OAM Emulation in AAL5 SDU mode, if LCCE can not support 619 transport of OAM cells across L2TP session. If OAM Cell Emulation is 620 configured or detected via some other means on one side, the other 621 LCCE MUST support OAM Cell Emulation as well. 623 This AVP is exchanged during session negotiation (in ICRQ, ICRP) or 624 during life of the session via SLI control message. If the other LCCE 625 can not support the OAM Cell Emulation, the associated L2TP session 626 MUST be torn down via CDN message with result code 22. 628 OAM Emulation AVP is a boolean AVP, having no Attribute Value. Its 629 absence is FALSE and its presence is TRUE. This AVP MAY be hidden 630 (the H bit MAY be 0 or 1). The M bit for this AVP SHOULD be set to 0, 631 but MAY vary (see Section 5.2 of [RFC3931]). The Length (before 632 hiding) of this AVP is 6. 634 8. ATM defects mapping and status notification 636 ATM OAM alarms or circuit status is indicated via Circuit Status AVP 637 as defined in Section 5.4.5 of [RFC3931]. For reference, usage of 638 this AVP is shown below. 640 0 1 641 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | Reserved |N|A| 644 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 646 The Value is a 16 bit mask with the two least significant bits 647 defined and the remaining bits are reserved for future use. Reserved 648 bits MUST be set to 0 when sending, and ignored upon receipt. 650 The A (Active) bit indicates whether the ATM Circuit is ACTIVE (1) or 651 INACTIVE (0). 653 The N (New) bit indicates whether the ATM circuit status indication 654 is for a new Circuit (1) or an existing ATM Circuit (0). 656 8.1 ATM Alarm Status AVP 658 An "ATM Alarm Status AVP", Attribute type 88, indicates the reason 659 for the ATM circuit status and specific alarm type, if any, to its 660 peer LCCE node. This OPTIONAL AVP MAY be present in SLI message with 661 Circuit Status AVP. 663 The Attribute Value field for this AVP has the following format: 665 0 1 2 3 666 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 1 667 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 668 | Circuit Status Reason | Alarm | 669 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 671 The Circuit status reason is a 2-octets unsigned integer and Alarm 672 Type is also a 2-octets unsigned integer. 674 This AVP MAY be hidden (the H bit MAY be 0 or 1). The M bit for this 675 AVP SHOULD be set to 0, but MAY vary (see Section 5.2 of [RFC3931]). 676 The Length (before hiding) of this AVP is 10 octets. 678 This AVP is sent in SLI message to indicate the additional 679 information about the ATM circuit status. 681 Circuit Status Reason values for the SLI message are as follows: 683 0 - Reserved 684 1 - No alarm or alarm cleared (default for Active Status) 685 2 - Unspecified or unknown Alarm Received (default for 686 Inactive Status) 687 3 - ATM Circuit received F1 Alarm on ingress LCCE 688 4 - ATM Circuit received F2 Alarm on ingress LCCE 689 5 - ATM Circuit received F3 Alarm on ingress LCCE 690 6 - ATM Circuit received F4 Alarm on ingress LCCE 691 7 - ATM Circuit received F5 Alarm on ingress LCCE 692 8 - ATM Circuit down due to ATM Port shutdown on Peer LCCE 693 9 - ATM Circuit down due to loop-back timeout on ingress LCCE 695 The general ATM Alarm failures are encoded as below: 697 0 - Reserved 698 1 - No Alarm type specified (default) 699 2 - Alarm Indication Signal (AIS) 700 3 - Remote Defect Indicator (RDI) 701 4 - Loss of Signal (LOS) 702 5 - Loss of pointer (LOP) 703 6 - Loss of framer (LOF) 704 7 - loopback cells (LB) 705 8 - Continuity Check (CC) 707 9. Applicability Statement 709 The ATM Pseudowire emulation described in this document allows for 710 carrying various ATM services across an IP packet switched network 711 (PSN). These ATM services can be PVC-based, PVP-based or Port-based. 712 In all cases, ATMPWs operate in a point-to-point deployment model. 714 ATMPWs support two modes of encapsulation: ATM AAL5-SDU Mode and ATM 715 Cell-Relay Mode. The following sections list their respective 716 characteristics in relationship to the native service. 718 9.1 ATM AAL5-SDU Mode 720 ATMPWs operating in AAL5-SDU Mode only support the transport of PVC- 721 based services. In this mode, the AAL5 CPCS-PDU from a single VCC is 722 reassembled at the ingress LCCE, and the AAL5 CPCS-SDU (i.e., the 723 AAL5 CPCS-PDU without CPCS-PDU Trailer or PAD octets, also referred 724 to as AAL5 CPCS-PDU Payload) is transported over the Pseudowire. 725 Therefore, Segmentation and Reassembly (SAR) functions are required 726 at the LCCEs. There is a one-to-one mapping between an ATM PVC and 727 an ATMPW operating in AAL5-SDU Mode, supporting bi-directional 728 transport of variable length frames. With the exception of optionally 729 transporting OAM cells, only ATM Adaptation Layer (AAL) type 5 frames 730 are carried in this mode, including Multiprotocol over AAL5 packets 731 [RFC2684]. 733 The following considerations stem from ATM AAL5-SDU Mode Pseudowires 734 not transporting the ATM cell headers and AAL5 CPCS-PDU Trailer (see 735 Section 5.1): 737 o An ATMPW operating in AAL5-SDU Mode conveys EFCI and CLP 738 information using the G and C bits in the ATM-Specific Sublayer. 739 In consequence, the EFCI and CLP value of individual ATM cells 740 that consititute the AAL5 frame may be lost across the ATMPW, 741 and CLP and EFCI transparency may not be maintained. The AAL5- 742 SDU Mode does not preserve EFCI and CLP value for every ATM cell 743 within the AAL5 PDU. The processing of these bits on ingress and 744 egress is defined in Section 4.1. 746 o Only the Least Significant Bit (LSB) from the CPCS-UU (User-to- 747 User indication) field in the CPCS-PDU Trailer is transported 748 using the ATM-Specific Sublayer (see Section 4.1). This bit 749 contains the Frame Relay C/R bit when FRF.8.1 Frame Relay / ATM 750 PVC Service Interworking [FRF8.1] is used. The CPCS-UU field is 751 not used in Multiprotocol Over AAL5 [RFC2684]. However, 752 applications that transfer user to user information using the 753 CPCS-UU octet would fail to operate. 755 o The CPI (Common Part Indicator) field in the CPCS-PDU Trailer is 756 also not transported across the ATMPW. This does not affect 757 Multiprotocol Over AAL5 applications since the field is used for 758 alignment and MUST be coded as 0x00 [RFC2684]. 760 o The trailing CRC field in the CPCS-PDU is stripped at the 761 ingress LCCE and not transported over the ATMPW operating in 762 AAL5-SDU Mode. It is in turn regenerated at the egress LCCE. 763 Since the CRC has end-to-end significance, this means that 764 errors introduced in the ATMPW payload during encapsulation or 765 transit across the packet switched network may not be detected. 766 To allow for payload integrity checking transparency on ATMPWs 767 operating in AAL5-SDU Mode using L2TP over IP or L2TP over 768 UDP/IP, the L2TPv3 session can utilize IPSec as specified in 769 Section 4.1.3 of [RFC3931]. 771 Some additional characteristics of the AAL5-SDU Mode are: 773 o The status of the ATM PVC is signaled between LCCEs using the 774 Circuit Status AVP. More granular cause values for the ATM 775 circuit status and specific ATM alarm types are signaled using 776 the ATM Alarm Status AVP (see Section 8.1). Additionally, loss 777 of connectivity between LCCEs can be detected by the L2TPv3 778 keepalive mechanism (see Section 4.4 in [RFC3931]). 780 o F5 OAM cell's relative order with respect to user data cells may 781 not be maintained. F5 OAM cells that arrive during the 782 reassembly of an AAL5 SDU are sent immediately over the PW and 783 before the AAL5 SDU payload. At egress, these OAM cells are sent 784 before the cells that comprise the AAL5-SDU. Therefore, 785 applications that rely on cell sequence integrity between OAM 786 and user data cells may not work. This includes Performance 787 Monitoring and Security OAM cells (see Section 5.1). In 788 addition, the AAL5-SDU service allows for OAM Emulation in which 789 OAM cells are not transported over the ATMPW (see Section 7). 790 This is advantageous for AAL5-SDU mode ATMPW implementations 791 that do not support cell transport using the T-bit. 793 o Fragmentation and Reassembly procedures may be used, both as 794 specified in Section 5 of [L2TPFRAG] or in the underlying PSN 795 (i.e., IP, etc) between tunnel endpoints as discussed in Section 796 4.1.4 of [RFC3931]. The procedures described in [L2TPFRAG] can 797 be used to support the maximum size of an AAL5 SDU, 2 ^ 16 - 1 798 (65535) octets. However, relying on fragmentation on the 799 L2TP/IPv4 packet between tunnel endpoints limits the maximum 800 size of the AAL5 SDU that can be transported, because the 801 maximum total length of an IPv4 datagram is already 65535 802 octets. In this case, the maximum AAL5 SDU that can be 803 transported is limited to 65535 minus the encapsulating headers, 804 24-36 octets for L2TP-over-IPv4 or 36-48 octets for L2TP-over- 805 UDP/IPv4. 806 When the AAL5 payload is IPv4, an additional option is to 807 fragment IP packets before tunnel encapsulation with L2TP/IP 808 (see Section 4.1.4 of [RFC3931]). 810 o Sequencing may be enabled on the ATMPW using the ATM-Specific 811 Sublayer Sequence Number field, to detect lost, duplicate, or 812 out-of-order frames on a per-session basis (see Section 4.2). 814 o Quality of Service characteristics such as throughput (cell 815 rates), burst sizes and delay variation can be provided by 816 leveraging Quality of Service features of the LCCEs and the 817 underlying PSN, increasing the faithfulness of ATMPWs. This 818 includes mapping ATM service categories to a compatible PSN 819 class of service. 821 9.2 ATM Cell-Relay Mode 823 In this mode, no reassembly takes place at the ingress LCCE. There 824 are no SAR requirements for LCCEs. Instead, ATM-Layer cells are 825 transported over the ATMPW. Consequently, all AAL types can be 826 transported over ATMPWs operating in Cell-Relay Mode. ATM Cell-Relay 827 Pseudowires can operate in three different modes (see Section 5.2): 828 ATM VCC, ATM VPC and ATM Port Cell-Relay Services. The following are 829 some of their characteristics: 831 o The ATM cells transported over Cell-Relay Mode ATMPWs consist of 832 a 4 byte ATM cell header and a 48-byte ATM Cell-payload (see 833 Section 5.2). The ATM Service Payload of a Cell-Relay Mode 834 ATMPW is a multiple of 52 bytes. The Header Error Checksum 835 (HEC) in the ATM cell header containing a CRC (Cyclic Redundancy 836 Check) calculated over the first 4 bytes of the ATM cell header 837 is not transported. Accordingly, the HEC field may not 838 accurately reflect errors on an end-to-end basis; errors or 839 corruption in the 4-byte ATM cell header introduced in the ATMPW 840 payload during encapsulation or transit across the PSN may not 841 be detected. To allow for payload integrity checking 842 transparency on ATMPWs operating in Cell-Relay Mode using L2TP 843 over IP or L2TP over UDP/IP, the L2TPv3 session can utilize 844 IPSec as specified in Section 4.1.3 of [RFC3931]. 846 o ATM PWs operating in Cell-Relay mode can transport a single ATM 847 cell or multiple concatenated cells (see Section 6). Cell 848 concatenation improves the bandwidth efficiency of the ATMPW (by 849 decreasing the overhead) but introduces latency and delay 850 variation. 852 o The status of the ATM PVC is signaled between LCCEs using the 853 Circuit Status AVP. More granular cause values for the ATM 854 circuit status and specific ATM alarm types are signaled using 855 the ATM Alarm Status AVP (see Section 8.1). Additionally, loss 856 of connectivity between LCCEs can be detected by the L2TPv3 857 keepalive mechanism (see Section 4.4 in [RFC3931]). 859 o ATM OAM cells are transported in the same fashion as user cells, 860 and in the same order as they are received. Therefore, 861 applications that rely on cell sequence integrity between OAM 862 and user data cells are not adversely affected. This includes 863 performance management and security applications that utilize 864 OAM cells (see Section 5.3). 866 o The maximum number of concatenated cells is limited by the MTU 867 size of the session (see Section 5.2 and Section 6). Therefore, 868 Fragmentation and Reassembly procedures are not used for Cell- 869 Relay ATMPWs. Concatenating cells to then fragment the resulting 870 packet defeats the purpose of cell concatenation. Concatenation 871 of cells and fragmentation act as inverse functions, with 872 additional processing but null net effect, and should not be 873 used together. 875 o Sequencing may be enabled on the ATMPW to detect lost, 876 duplicate, or out-of-order packets on a per-session basis (see 877 Section 4.2). 879 o Quality of Service characteristics such as throughput (cell 880 rates), burst sizes and delay variation can be provided by 881 leveraging Quality of Service features of the LCCEs and the 882 underlying PSN, increasing the faithfulness of ATMPWs. This 883 includes mapping ATM service categories to a compatible PSN 884 class of service, and mapping CLP and EFCI bits to PSN classes 885 of service. For example, mapping a CBR PVC to a class of 886 service with tight loss and delay characteristics, such as an EF 887 PHB if the PSN is an IP DiffServ-enabled domain. The following 888 characteristics of ATMPWs operating in Cell-Relay mode include 889 additional QoS considerations: 891 - ATM Cell transport VCC Pseudowires allow for mapping 892 multiple ATM VCCs to a single ATMPW. However a user may 893 wish to map a single ATM VCC per ATMPW to satisfy QoS 894 requirements (see Section 5.2.1). 896 - Cell-Relay ATMPWs allow for concatenating multiple cells in 897 a single Pseudowire PDU to improve bandwidth efficiency, 898 but may introduce latency and delay variation. 900 10. Congestion Control 902 As explained in [RFC3985], the PSN carrying the PW may be subject to 903 congestion, with congestion characteristics depending on PSN type, 904 network architecture, configuration, and loading. During congestion 905 the PSN may exhibit packet loss and PDV that will impact the timing 906 and data integrity of the ATMPW. During intervals of acute 907 congestion, some Cell-Relay ATMPWs may not be able to maintain 908 service. The inelastic nature of some ATM services reduces the risk 909 of congestion because the rates will not expand to consume all 910 available bandwidth, but on the other hand those ATM services cannot 911 arbitrarily reduce its load on the network to eliminate congestion 912 when it occurs. 914 Whenever possible, Cell-Relay ATMPWs should be run over traffic- 915 engineered PSNs providing bandwidth allocation and admission control 916 mechanisms. IntServ-enabled domains providing the Guaranteed Service 917 (GS) or DiffServ-enabled domains using Expedited Forwarding (EF) are 918 examples of traffic-engineered PSNs. Such PSNs will minimize loss and 919 delay while providing some degree of isolation of the Cell-Relay 920 ATMPW's effects from neighboring streams. 922 If the PSN is providing a best-effort service, then the following 923 best-effort service congestion avoidance considerations apply: Those 924 ATMPWs that carry constant bit rate (CBR) and VBR-rt (Variable Bit 925 Rate-real time) services across the PSN will most probably not behave 926 in a TCP-friendly manner prescribed by [RFC2914]. In the presence of 927 services that reduce transmission rate, ATMPWs carrying CBR and VBR- 928 rt traffic SHOULD be halted when acute congestion is detected, in 929 order to allow for other traffic or the network infrastructure itself 930 to continue. ATMPWs carrying UBR (Unspecified Bit Rate) traffic, 931 which are equivalent to best-effort IP service, need not be halted 932 during acute congestion and MAY have cells delayed or dropped by the 933 ingress PE if necessary. ATMPWs carrying VBR-nrt (Variable Bit 934 Rate-non real time) services may or may not behave in a TCP-friendly 935 manner, depending on the end user application, but are most likely 936 safe to continue operating, since the end-user application is 937 expected to be delay-insensitive and may also be somewhat loss- 938 insensitive. 940 LCCEs SHOULD monitor for congestion (for example by measuring packet 941 loss or as specified in Section 6.5 of [RFC3985]) in order to ensure 942 that the ATM service may be maintained. When severe congestion is 943 detected (for example when enabling Sequencing and detecting that the 944 packet loss is higher than a threshold) the ATM service SHOULD be 945 terminated by tearing down the L2TP session via a CDN message. The 946 PW may be restarted by manual intervention, or by automatic means 947 after an appropriate waiting time. 949 11. Security Considerations 951 ATM over L2TPv3 is subject to the security considerations defined in 952 [RFC3931]. There are no additional considerations specific to 953 carrying ATM that are not present carrying other data link types. 955 12. IANA Considerations 957 The signaling mechanisms defined in this document rely upon the 958 allocation of following ATM Pseudowire Types (see Pseudowire 959 Capabilities List as defined in 5.4.3 of [RFC3931] and L2TPv3 960 Pseudowire Types in 10.6 of [RFC3931]) by the IANA (number space 961 created as part of publication of [RFC3931]): 963 Pseudowire Types 964 ---------------- 966 0x0002 ATM AAL5 SDU VCC transport 967 0x0003 ATM Cell transparent Port Mode 968 0x0009 ATM Cell transport VCC Mode 969 0x000A ATM Cell transport VPC Mode 971 12.1 L2-Specific Sublayer Type 973 This number space is created and maintained per [RFC3931]. 975 L2-Specific Sublayer Type 976 ------------------------- 978 2 - ATM L2-Specific Sublayer present 980 12.2 Control Message Attribute Value Pairs (AVPs) 982 This number space is managed by IANA as per [BCP0068]. 984 A summary of the three new AVPs follows: 986 Control Message Attribute Value Pairs 988 Attribute 989 Type Description 990 --------- ---------------------------------- 991 86 ATM Maximum Concatenated Cells AVP 992 87 OAM Emulation Required AVP 993 88 ATM Alarm Status AVP 995 12.3 Result Code AVP Values 997 This number space is managed by IANA as per [BCP0068]. 999 New Result Code value for the CDN message is defined in Section 7. 1000 Following is a summary: 1002 Result Code AVP (Attribute Type 1) Values 1003 ----------------------------------------- 1005 General Error Codes 1007 22 - Session not established due to other LCCE 1008 can not support the OAM Cell Emulation, 1010 12.4 ATM Alarm Status AVP Values 1012 This is a new registry for IANA to maintain. 1014 New Attribute values for the SLI message is defined in Section 8. 1015 Following is a summary: 1017 ATM Alarm Status AVP (Attribute Type 88) Values 1018 ----------------------------------------------- 1020 Circuit Status Reason values for the SLI message are as follows: 1022 0 - Reserved 1023 1 - No alarm or alarm cleared (default for Active Status) 1024 2 - Unspecified or unknown Alarm Received (default for 1025 Inactive Status) 1026 3 - ATM Circuit received F1 Alarm on ingress LCCE 1027 4 - ATM Circuit received F2 Alarm on ingress LCCE 1028 5 - ATM Circuit received F3 Alarm on ingress LCCE 1029 6 - ATM Circuit received F4 Alarm on ingress LCCE 1030 7 - ATM Circuit received F5 Alarm on ingress LCCE 1031 8 - ATM Circuit down due to ATM Port shutdown on Peer LCCE 1032 9 - ATM Circuit down due to loop-back timeout on ingress LCCE 1034 The general ATM Alarm failures are encoded as below: 1036 0 - Reserved 1037 1 - No Alarm type specified (default) 1038 2 - Alarm Indication Signal (AIS) 1039 3 - Remote Defect Indicator (RDI) 1040 4 - Loss of Signal (LOS) 1041 5 - Loss of pointer (LOP) 1042 6 - Loss of framer (LOF) 1043 7 - loopback cells (LB) 1044 8 - Continuity Check (CC) 1046 12.5 ATM-Specific Sublayer bits 1048 This is a new registry for IANA to maintain. 1050 The ATM-Specific Sublayer contains 8 bits in the low-order portion of 1051 the header. Reserved bits may be assigned by IETF Consensus 1052 [RFC2434]. 1054 Bit 0 - Reserved 1055 Bit 1 - S (Sequence) bit 1056 Bit 2 - B (Fragmentation) bit 1057 Bit 3 - E (Fragmentation) bit 1058 Bit 4 - T (Transport type) bit 1059 Bit 5 - G (EFCI) bit 1060 Bit 6 - C (CLP) bit 1061 Bit 7 - U (Command/Response) bit 1063 13. Acknowledgments 1065 Thanks for the contribution from Jed Lau, Pony Zhu, Prasad Yaditi, 1066 Durai and Jaya Kumar. 1068 Many Thanks to Srinivas Kotamraju for editorial review. 1070 Thanks to Shoou Yiu and Fred Shu for their valuable time to review 1071 this document. 1073 14. References 1075 14.1 Normative References 1077 [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling 1078 Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. 1080 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1081 Requirement Levels", BCP 14, RFC 2119, March 1997. 1083 14.2 Informative References 1085 [PWE3ATM] Martini, L., "Encapsulation Methods for Transport of ATM 1086 Over MPLS Networks", draft-ietf-pwe3-atm-encap-10 (work in 1087 progress), September 2005. 1089 [L2TPFRAG] Malis, A. and M. Townsley, "PWE3 Fragmentation and 1090 Reassembly", draft-ietf-pwe3-fragmentation-10 (work in 1091 progress), November 2005. 1093 [FRF8.1] "Frame Relay / ATM PVC Service Interworking 1094 Implementation Agreement (FRF 8.1)", Frame Relay 1095 Forum 2000. 1097 [BCP0068] Townsley, W., "Layer Two Tunneling Protocol (L2TP) 1098 Internet Assigned Numbers Authority (IANA) Considerations 1099 Update", BCP 68, RFC 3438, December 2002. 1101 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1102 IANA Considerations Section in RFCs", BCP 26, RFC 2434, 1103 October 1998. 1105 [I610-1] ITU-T Recommendation I.610 (1999): B-ISDN operation and 1106 maintenance principles and functions 1108 [I610-2] ITU-T Recommendation I.610, Corrigendum 1 (2000): 1109 B-ISDN operation and maintenance principles and 1110 functions (corrigendum 1) 1112 [I610-3] ITU-T Recommendation I.610, Amendment 1 (2000): B-ISDN 1113 operation and maintenance principles and functions 1114 (Amendment 1) 1116 [ATMSEC] ATM Forum Specification, af-sec-0100.002 (2001): ATM 1117 Security Specification version 1.1 1119 [RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol Encapsulation 1120 over ATM Adaptation Layer 5", RFC 2684, September 1999. 1122 [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to- 1123 Edge (PWE3) Architecture", RFC 3985, March 2005. 1125 [RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, 1126 RFC 2914, September 2000. 1128 15. Authors' Addresses 1130 Sanjeev Singh 1131 Cisco Systems 1132 170 W. Tasman Drive 1133 San Jose, CA 95134 1134 sanjeevs@cisco.com 1136 W. Mark Townsley 1137 Cisco Systems 1138 7025 Kit Creek Road 1139 PO Box 14987 1140 Research Triangle Park, NC 27709 1141 mark@townsley.net 1143 Carlos Pignataro 1144 Cisco Systems 1145 7025 Kit Creek Road 1146 PO Box 14987 1147 Research Triangle Park, NC 27709 1148 cpignata@cisco.com 1150 Intellectual Property Statement 1152 The IETF takes no position regarding the validity or scope of any 1153 Intellectual Property Rights or other rights that might be claimed to 1154 pertain to the implementation or use of the technology described in 1155 this document or the extent to which any license under such rights 1156 might or might not be available; nor does it represent that it has 1157 made any independent effort to identify any such rights. Information 1158 on the procedures with respect to rights in RFC documents can be 1159 found in BCP 78 and BCP 79. 1161 Copies of IPR disclosures made to the IETF Secretariat and any 1162 assurances of licenses to be made available, or the result of an 1163 attempt made to obtain a general license or permission for the use of 1164 such proprietary rights by implementers or users of this 1165 specification can be obtained from the IETF on-line IPR repository at 1166 http://www.ietf.org/ipr. 1168 The IETF invites any interested party to bring to its attention any 1169 copyrights, patents or patent applications, or other proprietary 1170 rights that may cover technology that may be required to implement 1171 this standard. Please address the information to the IETF at 1172 ietf-ipr@ietf.org. 1174 Disclaimer of Validity 1176 This document and the information contained herein are provided on 1177 an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE 1178 REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE 1179 INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR 1180 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 1181 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1182 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1184 Copyright Statement 1186 Copyright (C) The Internet Society (2006). 1188 This document is subject to the rights, licenses and restrictions 1189 contained in BCP 78, and except as set forth therein, the authors 1190 retain all their rights. 1192 Acknowledgment 1194 Funding for the RFC Editor function is currently provided by the 1195 Internet Society.