idnits 2.17.1 draft-ietf-tsvwg-addip-sctp-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. ** There is 1 instance of too long lines in the document, the longest one being 1 character in excess of 72. ** The abstract seems to contain references ([RFC2960]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. == There are 4 instances of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. == There are 3 instances of lines with private range IPv4 addresses in the document. If these are generic example addresses, they should be changed to use any of the ranges defined in RFC 6890 (or successor): 192.0.2.x, 198.51.100.x or 203.0.113.x. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == Line 981 has weird spacing: '...er will treat...' == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). == 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 'SHOULD not' in this paragraph: R6) An ASCONF-ACK SHOULD not be larger than the path MTU. In some circumstances an ASCONF-ACK may exceed the path MTU and in such a case IP fragmentation should be used to transmit the chunk. -- 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 (February 26, 2003) is 7724 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) -- Looks like a reference, but probably isn't: 'RFC2960' on line 50 == Unused Reference: '1' is defined on line 1159, but no explicit reference was found in the text ** Obsolete normative reference: RFC 2402 (ref. '3') (Obsoleted by RFC 4302, RFC 4305) ** Obsolete normative reference: RFC 2434 (ref. '4') (Obsoleted by RFC 5226) ** Obsolete normative reference: RFC 2960 (ref. '5') (Obsoleted by RFC 4960) Summary: 7 errors (**), 0 flaws (~~), 8 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Stewart 3 Internet-Draft M. Ramalho 4 Expires: August 27, 2003 Cisco Systems, Inc. 5 Q. Xie 6 Motorola, Inc. 7 M. Tuexen 9 I. Rytina 10 M. Belinchon 11 Ericsson 12 P. Conrad 13 Temple University 14 February 26, 2003 16 Stream Control Transmission Protocol (SCTP) Dynamic Address 17 Reconfiguration 18 draft-ietf-tsvwg-addip-sctp-07.txt 20 Status of this Memo 22 This document is an Internet-Draft and is in full conformance with 23 all provisions of Section 10 of RFC2026. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF), its areas, and its working groups. Note that 27 other groups may also distribute working documents as 28 Internet-Drafts. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 The list of current Internet-Drafts can be accessed at http:// 36 www.ietf.org/ietf/1id-abstracts.txt. 38 The list of Internet-Draft Shadow Directories can be accessed at 39 http://www.ietf.org/shadow.html. 41 This Internet-Draft will expire on August 27, 2003. 43 Copyright Notice 45 Copyright (C) The Internet Society (2003). All Rights Reserved. 47 Abstract 49 This document describes extensions to the Stream Control Transmission 50 Protocol (SCTP) [RFC2960] that provides a method to reconfigure IP 51 address information on an existing association. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 56 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4 57 3. Additional Chunks and Parameters . . . . . . . . . . . . . . 5 58 3.1 New Chunk Types . . . . . . . . . . . . . . . . . . . . . . 5 59 3.1.1 Address Configuration Change Chunk (ASCONF) . . . . . . . . 5 60 3.1.2 Address Configuration Acknowledgment Chunk (ASCONF-ACK) . . 6 61 3.2 New Parameter Types . . . . . . . . . . . . . . . . . . . . 7 62 3.2.1 Add IP Address . . . . . . . . . . . . . . . . . . . . . . . 8 63 3.2.2 Delete IP Address . . . . . . . . . . . . . . . . . . . . . 9 64 3.2.3 Error Cause Indication . . . . . . . . . . . . . . . . . . . 10 65 3.2.4 Set Primary IP Address . . . . . . . . . . . . . . . . . . . 11 66 3.2.5 Success Indication . . . . . . . . . . . . . . . . . . . . . 12 67 3.2.6 Adaptation Layer Indication . . . . . . . . . . . . . . . . 12 68 3.3 New Error Causes . . . . . . . . . . . . . . . . . . . . . . 13 69 3.3.1 Error Cause: Request to Delete Last Remaining IP Address . . 13 70 3.3.2 Error Cause: Operation Refused Due to Resource Shortage . . 14 71 3.3.3 Error Cause: Request to Delete Source IP Address . . . . . . 15 72 3.3.4 Error Cause: Association Aborted due to illegal 73 ASCONF-ACK . . . . . . . . . . . . . . . . . . . . . . . . . 16 74 3.3.5 Error Cause: Request refused - no authorization. . . . . . . 16 75 4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 17 76 4.1 ASCONF Chunk Procedures . . . . . . . . . . . . . . . . . . 17 77 4.1.1 Congestion Control of ASCONF Chunks . . . . . . . . . . . . 18 78 4.2 Upon reception of an ASCONF Chunk. . . . . . . . . . . . . . 19 79 4.3 General rules for address manipulation . . . . . . . . . . . 21 80 4.3.1 A special case for OOTB ABORT chunks . . . . . . . . . . . . 25 81 4.3.2 A special case for changing an address. . . . . . . . . . . 25 82 4.4 Setting of the primary address . . . . . . . . . . . . . . . 26 83 5. Security Considerations . . . . . . . . . . . . . . . . . . 27 84 6. IANA considerations . . . . . . . . . . . . . . . . . . . . 28 85 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 29 86 References . . . . . . . . . . . . . . . . . . . . . . . . . 30 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 30 88 A. Abstract Address Handling . . . . . . . . . . . . . . . . . 32 89 A.1 General remarks . . . . . . . . . . . . . . . . . . . . . . 32 90 A.2 Generalized endpoints . . . . . . . . . . . . . . . . . . . 32 91 A.3 Associations . . . . . . . . . . . . . . . . . . . . . . . . 33 92 A.4 Relationship with RFC 2960 . . . . . . . . . . . . . . . . . 34 93 A.5 Rules for address manipulation . . . . . . . . . . . . . . . 34 94 Intellectual Property and Copyright Statements . . . . . . . 35 96 1. Introduction 98 To extend the utility and application scenarios of SCTP, this 99 document introduces optional extensions that provide SCTP with the 100 ability to: 102 1. reconfigure IP address information on an existing association. 104 2. set the remote primary path. 106 3. exchange adaptation layer information during association setup. 108 These extensions enable SCTP to be utilized in the following 109 applications: 111 1. For computational or networking platforms that allow addition/ 112 removal of physical interface cards this feature can provide a 113 graceful method to add to the interfaces of an existing 114 association. For IPv6 this feature allows renumbering of 115 existing associations. 117 2. This provides a method for an endpoint to request that its peer 118 set its primary destination address. This can be useful when an 119 address is about to be deleted, or when an endpoint has some 120 predetermined knowledge about which is the preferred address to 121 receive SCTP packets upon. 123 3. This feature can be used to extend the usability of SCTP without 124 modifying it by allowing endpoints to exchange some information 125 during association setup. 127 2. Conventions 129 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, 130 SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when 131 they appear in this document, are to be interpreted as described in 132 RFC2119 [2]. 134 3. Additional Chunks and Parameters 136 This section describes the addition of two new chunks and, six new 137 parameters to allow: 139 o Dynamic addition of IP Addresses to an association. 141 o Dynamic deletion of IP Addresses from an association. 143 o A request to set the primary address the peer will use when 144 sending to an endpoint. 146 Additionally, this section describes three new error causes that 147 support these new chunks and parameters. 149 3.1 New Chunk Types 151 This section defines two new chunk types that will be used to 152 transfer the control information reliably. Table 1 illustrates the 153 two new chunk types. 155 Chunk Type Chunk Name 156 -------------------------------------------------------------- 157 0xC1 Address Configuration Change Chunk (ASCONF) 158 0x80 Address Configuration Acknowledgment (ASCONF-ACK) 160 Table 1: Address Configuration Chunks 162 It should be noted that the ASCONF Chunk format requires the receiver 163 to report to the sender if it does not understand the ASCONF Chunk. 164 This is accomplished by setting the upper bits in the chunk type as 165 described in RFC2960 [5] section 3.2. Note that the upper two bits 166 in the ASCONF Chunk are set to one. As defined in RFC2960 [5] 167 section 3.2, setting these upper bits in this manner will cause the 168 receiver that does not understand this chunk to skip the chunk and 169 continue processing, but report in an Operation Error Chunk using the 170 'Unrecognized Chunk Type' cause of error. 172 3.1.1 Address Configuration Change Chunk (ASCONF) 174 This chunk is used to communicate to the remote endpoint one of the 175 configuration change requests that MUST be acknowledged. The 176 information carried in the ASCONF Chunk uses the form of a 177 Type-Length-Value (TLV), as described in "3.2.1 Optional/ 178 Variable-length Parameter Format" in RFC2960 [5], forall variable 179 parameters. 181 0 1 2 3 182 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 1 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 | Type = 0xC1 | Chunk Flags | Chunk Length | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 186 | Serial Number | 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 | Address Parameter | 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 190 | ASCONF Parameter #1 | 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 \ \ 193 / .... / 194 \ \ 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | ASCONF Parameter #N | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 Serial Number : 32 bits (unsigned integer) 201 This value represents a Serial Number for the ASCONF Chunk. The 202 valid range of Serial Number is from 0 to 4294967295 (2**32 - 1). 203 Serial Numbers wrap back to 0 after reaching 4294967295. 205 Address Parameter : 8 or 20 bytes (depending on type) 207 This field contains an address parameter, either IPv6 or IPv4, from 208 RFC2960 [5]. The address is an address of the sender of the ASCONF 209 chunk, the address MUST be considered part of the association by the 210 peer endpoint (the receiver of the ASCONF chunk). This field may be 211 used by the receiver of the ASCONF to help in finding the 212 association. This parameter MUST be present in every ASCONF message 213 i.e. it is a mandatory TLV parameter. 215 Note the host name address parameter is NOT allowed and MUST be 216 ignored if received in any ASCONF message. 218 ASCONF Parameter: TLV format 220 Each Address configuration change is represented by a TLV parameter 221 as defined in Section 3.2. One or more requests may be present in an 222 ASCONF Chunk. 224 3.1.2 Address Configuration Acknowledgment Chunk (ASCONF-ACK) 226 This chunk is used by the receiver of an ASCONF Chunk to acknowledge 227 the reception. It carries zero or more results for any ASCONF 228 Parameters that were processed by the receiver. 230 0 1 2 3 231 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 1 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 | Type = 0x80 | Chunk Flags | Chunk Length | 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 | Serial Number | 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 237 | ASCONF Parameter Response#1 | 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 \ \ 240 / .... / 241 \ \ 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | ASCONF Parameter Response#N | 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 Serial Number : 32 bits (unsigned integer) 248 This value represents the Serial Number for the received ASCONF Chunk 249 that is acknowledged by this chunk. This value is copied from the 250 received ASCONF Chunk. 252 ASCONF Parameter Response : TLV format 254 The ASCONF Parameter Response is used in the ASCONF-ACK to report 255 status of ASCONF processing. By default, if a responding endpoint 256 does not include any Error Cause, a success is indicated. Thus a 257 sender of an ASCONF-ACK MAY indicate complete success of all TLVs in 258 an ASCONF by returning only the Chunk Type, Chunk Flags, Chunk Length 259 (set to 8) and the Serial Number. 261 3.2 New Parameter Types 263 The six new parameters added follow the format defined in section 264 3.2.1 of RFC2960 [5]. Table 2 and 3 describes the parameters. 266 Address Configuration Parameters Parameter Type 267 ------------------------------------------------- 268 Add IP Address 0xC001 269 Delete IP Address 0xC002 270 Set Primary Address 0xC004 271 Adaption Layer Indication 0xC006 273 Table 2: Parameters used in ASCONF Parameter 275 Address Configuration Parameters Parameter Type 276 ------------------------------------------------- 277 Error Cause Indication 0xC003 278 Success Indication 0xC005 280 Table 3: Parameters used in ASCONF Parameter Response 282 3.2.1 Add IP Address 284 0 1 2 3 285 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 1 286 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 287 | Type = 0xC001 | Length = Variable | 288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 289 | ASCONF-Request Correlation ID | 290 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 291 | Address Parameter | 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 ASCONF-Request Correlation ID: 32 bits 296 This is an opaque integer assigned by the sender to identify each 297 request parameter. It is in host byte order and is only meaningful 298 to the sender. The receiver of the ASCONF Chunk will copy this 32 299 bit value into the ASCONF Response Correlation ID field of the 300 ASCONF-ACK response parameter. The sender of the ASCONF can use this 301 same value in the ASCONF-ACK to find which request the response is 302 for. 304 Address Parameter: TLV 306 This field contains an IPv4 or IPv6 address parameter as described in 307 3.3.2.1 of RFC2960 [5]. The complete TLV is wrapped within this 308 parameter. It informs the receiver that the address specified is to 309 be added to the existing association. 311 An example TLV requesting that the IPv4 address 10.1.1.1 be added to 312 the association would look as follows: 314 +--------------------------------+ 315 | Type=0xC001 | Length = 16 | 316 +--------------------------------+ 317 | C-ID = 0x01023474 | 318 +--------------------------------+ 319 | Type=5 | Length = 8 | 320 +----------------+---------------+ 321 | Value=0x0a010101 | 322 +----------------+---------------+ 324 Valid Chunk Appearance 326 The Add IP Address parameter may only appear in the ASCONF Chunk 327 type. 329 3.2.2 Delete IP Address 331 0 1 2 3 332 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 1 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 | Type =0xC002 | Length = Variable | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | ASCONF-Request Correlation ID | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 338 | Address Parameter | 339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 341 ASCONF-Request Correlation ID: 32 bits 343 This is an opaque integer assigned by the sender to identify each 344 request parameter. It is in host byte order and is only meaningful 345 to the sender. The receiver of the ASCONF Chunk will copy this 32 346 bit value into the ASCONF Response Correlation ID field of the 347 ASCONF-ACK response parameter. The sender of the ASCONF can use this 348 same value in the ASCONF-ACK to find which request the response is 349 for. 351 Address Parameter: TLV 353 This field contains an IPv4 or IPv6 address parameter as described in 354 3.3.2.1 of RFC2960 [5]. The complete TLV is wrapped within this 355 parameter. It informs the receiver that the address specified is to 356 be removed from the existing association. 358 An example TLV deleting the IPv4 address 10.1.1.1 from an existing 359 association would look as follows: 361 +--------------------------------+ 362 | Type=0xC002 | Length = 16 | 363 +--------------------------------+ 364 | C-ID = 0x01023476 | 365 +--------------------------------+ 366 | Type=5 | Length = 8 | 367 +----------------+---------------+ 368 | Value=0x0a010101 | 369 +----------------+---------------+ 371 Valid Chunk Appearance 373 The Delete IP Address parameter may only appear in the ASCONF Chunk 374 type. 376 3.2.3 Error Cause Indication 378 0 1 2 3 379 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 1 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 381 | Type = 0xC003 | Length = Variable | 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 | ASCONF-Response Correlation ID | 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | Error Cause(s) or Return Info on Success | 386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 ASCONF-Response Correlation ID: 32 bits 390 This is an opaque integer assigned by the sender to identify each 391 request parameter. The receiver of the ASCONF Chunk will copy this 392 32 bit value from the ASCONF-Request Correlation ID into the ASCONF 393 Response Correlation ID field so the peer can easily correlate the 394 request to this response. 396 Error Cause(s): TLV(s) 398 When reporting an error this response parameter is used to wrap one 399 or more standard error causes normally found within an SCTP 400 Operational Error or SCTP Abort (as defined in RFC2960 [5]). The 401 Error Cause(s) follow the format defined in section 3.3.10 of RFC2960 402 [5]. 404 Valid Chunk Appearance 406 The Error Cause Indication parameter may only appear in the 407 ASCONF-ACK chunk type. 409 3.2.4 Set Primary IP Address 411 0 1 2 3 412 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 1 413 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 414 | Type =0xC004 | Length = Variable | 415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 416 | ASCONF-Request Correlation ID | 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 | Address Parameter | 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 ASCONF-Request Correlation ID: 32 bits 423 This is an opaque integer assigned by the sender to identify each 424 request parameter. It is in host byte order and is only meaningful 425 to the sender. The receiver of the ASCONF Chunk will copy this 32 426 bit value into the ASCONF Response Correlation ID field of the 427 ASCONF-ACK response parameter. The sender of the ASCONF can use this 428 same value in the ASCONF-ACK to find which request the response is 429 for. 431 Address Parameter: TLV 433 This field contains an IPv4 or IPv6 address parameter as described in 434 3.3.2.1 of RFC2960 [5]. The complete TLV is wrapped within this 435 parameter. It requests the receiver to mark the specified address as 436 the primary address to send data to (see section 5.1.2 of RFC2960 437 [5]). The receiver MAY mark this as its primary upon receiving this 438 request. 440 An example TLV requesting that the IPv4 address 10.1.1.1 be made the 441 primary destination address would look as follows: 443 +--------------------------------+ 444 | Type=0xC004 | Length = 16 | 445 +--------------------------------+ 446 | C-ID = 0x01023479 | 447 +--------------------------------+ 448 | Type=5 | Length = 8 | 449 +----------------+---------------+ 450 | Value=0x0a010101 | 451 +----------------+---------------+ 453 Valid Chunk Appearance 455 The Set Primary IP Address parameter may appear in the ASCONF Chunk, 456 the INIT, or the INIT-ACK chunk type. The inclusion of this 457 parameter in the INIT or INIT-ACK can be used to indicate an initial 458 preference of primary address. 460 3.2.5 Success Indication 462 0 1 2 3 463 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 1 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 | Type = 0xC005 | Length = 8 | 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 | ASCONF-Response Correlation ID | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 470 By default if a responding endpoint does not report an error for any 471 requested TLV, a success is implicitly indicated. Thus a sender of a 472 ASCONF-ACK MAY indicate complete success of all TLVs in an ASCONF by 473 returning only the Chunk Type, Chunk Flags, Chunk Length (set to 8) 474 and the Serial Number. 476 The responding endpoint MAY also choose to explicitly report a 477 success for a requested TLV, by returning a success report ASCONF 478 Parameter Response. 480 ASCONF-Response Correlation ID: 32 bits 482 This is an opaque integer assigned by the sender to identify each 483 request parameter. The receiver of the ASCONF Chunk will copy this 484 32 bit value from the ASCONF-Request Correlation ID into the ASCONF 485 Response Correlation ID field so the peer can easily correlate the 486 request to this response. 488 Valid Chunk Appearance 490 The Success Indication parameter may only appear in the ASCONF-ACK 491 chunk type. 493 3.2.6 Adaptation Layer Indication 495 0 1 2 3 496 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 1 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 | Type =0xC006 | Length = Variable | 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Adaption Code point | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 This parameter is specified for the communication of peer upper layer 504 protocols. It is envisioned to be used for flow control and other 505 adaptation layers that require an indication to be carried in the 506 INIT and INIT-ACK. Each adaptation layer that is defined that wishes 507 to use this parameter MUST specify a an adaption code point in an 508 appropriate RFC defining its use and meaning. This parameter SHOULD 509 NOT be examined by the receiving SCTP implementation and should be 510 passed opaquely to the upper layer protocol. 512 Valid Chunk Appearance 514 The Adaptation Layer Indication parameter may appear in INIT or 515 INIT-ACK chunk and SHOULD be passed to the receivers upper layer 516 protocol. 518 3.3 New Error Causes 520 Four new Error Causes are added to the SCTP Operational Errors, 521 primarily for use in the ASCONF-ACK chunk. 523 Cause Code 524 Value Cause Code 525 --------- ---------------- 526 0x0100 Request to Delete Last Remaining IP Address. 527 0x0101 Operation Refused Due to Resource Shortage. 528 0x0102 Request to Delete Source IP Address. 529 0x0103 Association Aborted due to illegal ASCONF-ACK 530 0x0104 Request refused - no authorization. 532 Table 4: New Error Causes 534 3.3.1 Error Cause: Request to Delete Last Remaining IP Address 536 Cause of error 538 Request to Delete Last Remaining IP address: The receiver of this 539 error sent a request to delete the last IP address from its 540 association with its peer. This error indicates that the request is 541 rejected. 543 0 1 2 3 544 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 1 545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 546 | Cause Code=0x0100 | Cause Length=Variable | 547 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 548 \ TLV-Copied-From-ASCONF / 549 / \ 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 552 An example of a failed delete in an Error Cause TLV would look as 553 follows in the response ASCONF-ACK message: 555 +--------------------------------+ 556 | Type = 0xC003 | Length = 24 | 557 +--------------------------------+ 558 | Cause=0x0100 | Length = 20 | 559 +----------------+---------------+ 560 | Type= 0xC002 | Length = 16 | 561 +----------------+---------------+ 562 | C-ID = 0x01023476 | 563 +--------------------------------+ 564 | Type=0x0005 | Length = 8 | 565 +----------------+---------------+ 566 | Value=0x0A010101 | 567 +----------------+---------------+ 569 3.3.2 Error Cause: Operation Refused Due to Resource Shortage 571 Cause of error 573 This error cause is used to report a failure by the receiver to 574 perform the requested operation due to a lack of resources. The 575 entire TLV that is refused is copied from the ASCONF into the error 576 cause. 578 0 1 2 3 579 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 1 580 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 581 | Cause Code=0x0101 | Cause Length=Variable | 582 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 \ TLV-Copied-From-ASCONF / 584 / \ 585 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 587 An example of a failed addition in an Error Cause TLV would look as 588 follows in the response ASCONF-ACK message: 590 +--------------------------------+ 591 | Type = 0xC003 | Length = 24 | 592 +--------------------------------+ 593 | Cause=0x0101 | Length = 20 | 594 +----------------+---------------+ 595 | Type=0xC001 | Length = 16 | 596 +--------------------------------+ 597 | C-ID = 0x01023474 | 598 +--------------------------------+ 599 | Type=0x0005 | Length = 8 | 600 +----------------+---------------+ 601 | Value=0x0A010101 | 602 +----------------+---------------+ 604 3.3.3 Error Cause: Request to Delete Source IP Address 606 Cause of error 608 Request to Delete Source IP Address: The receiver of this error sent 609 a request to delete the source IP address of the ASCONF message. 610 This error indicates that the request is rejected. 612 0 1 2 3 613 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 1 614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 615 | Cause Code=0x0102 | Cause Length=Variable | 616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 617 \ TLV-Copied-From-ASCONF / 618 / \ 619 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 An example of a failed delete in an Error Cause TLV would look as 622 follows in the response ASCONF-ACK message: 624 +--------------------------------+ 625 | Type = 0xC003 | Length = 24 | 626 +--------------------------------+ 627 | Cause=0x0102 | Length = 20 | 628 +----------------+---------------+ 629 | Type=0xC002 | Length = 16 | 630 +----------------+---------------+ 631 | C-ID = 0x01023476 | 632 +--------------------------------+ 633 | Type=0x0005 | Length = 8 | 634 +----------------+---------------+ 635 | Value=0x0A010101 | 636 +----------------+---------------+ 638 IMPLEMENTATION NOTE: It is unlikely that an endpoint would source a 639 packet from the address being deleted, unless the endpoint does not 640 do proper source address selection. 642 3.3.4 Error Cause: Association Aborted due to illegal ASCONF-ACK 644 This error is to be included in an ABORT that is generated due to the 645 reception of an ASCONF-ACK that was not expected but is larger than 646 the current sequence number (see Section 4.3 Rule D0 ). Note that a 647 sequence number is larger than the last acked sequence number if it 648 is either the next sequence or no more than 2^^31 greater than the 649 current sequence number. 651 0 1 2 3 652 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 1 653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 654 | Cause Code=0x0103 | Cause Length=4 | 655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 657 3.3.5 Error Cause: Request refused - no authorization. 659 Cause of error 661 This error cause may be included to reject a request based on local 662 security policies. 664 0 1 2 3 665 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 1 666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 | Cause Code=0x0104 | Cause Length=Variable | 668 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 \ TLV-Copied-From-ASCONF / 670 / \ 671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 673 4. Procedures 675 This section will lay out the specific procedures for address 676 configuration change chunk type and its processing. 678 4.1 ASCONF Chunk Procedures 680 When an endpoint has an ASCONF signaled change to be sent to the 681 remote endpoint it should do the following: 683 A1) Create an ASCONF Chunk as defined in Section 3.1.1. The chunk 684 should contain all of the TLV(s) of information necessary to be 685 sent to the remote endpoint, and unique correlation identities for 686 each request. 688 A2) A serial number should be assigned to the Chunk. The serial 689 number should be a monotonically increasing number. The serial 690 number SHOULD be initialized at the start of the association to 691 the same value as the Initial TSN and every time a new ASCONF 692 chunk is created it is incremented by one after assigning the 693 serial number to the newly created chunk . 695 A3) If no ASCONF Chunk is outstanding (un-acknowledged) with the 696 remote peer, send the chunk. 698 A4) Start a T-4 RTO timer, using the RTO value of the selected 699 destination address (normally the primary path; see RFC2960 [5] 700 section 6.4 for details). 702 A5) When the ASCONF-ACK that acknowledges the serial number last sent 703 arrives, stop the T-4 RTO timer, and clear the appropriate 704 association and destination error counters as defined in RFC2960 705 [5] section 8.1 and 8.2. 707 A6) Process all of the TLVs within the ASCONF-ACK to find out 708 particular status information returned to the various requests 709 that were sent. Use the Correlation IDs to correlate the request 710 and the responses. 712 A7) If an error response is received for a TLV parameter, all TLVs 713 with no response before the failed TLV are considered successful 714 if not reported. All TLVs after the failed response are 715 considered unsuccessful unless a specific success indication is 716 present for the parameter. 718 A8) If there is no response(s) to specific TLV parameter(s), and no 719 failures are indicated, then all request(s) are considered 720 successful. 722 A9) If the peer responds to an ASCONF with an ERROR chunk reporting 723 that it did not recognized the ASCONF chunk type, the sender of 724 the ASCONF MUST NOT send any further ASCONF chunks and MUST stop 725 its T-4 timer. 727 If the T-4 RTO timer expires the endpoint should do the following: 729 B1) Increment the error counters and perform path failure detection 730 on the appropriate destination address as defined in RFC2960 [5] 731 section 8.1 and 8.2. 733 B2) Increment the association error counters and perform endpoint 734 failure detection on the association as defined in RFC2960 [5] 735 section 8.1 and 8.2. 737 B3) Back-off the destination address RTO value to which the ASCONF 738 chunk was sent by doubling the RTO timer value. 740 Note: The RTO value is used in the setting of all timer types for 741 SCTP. Each destination address has a single RTO estimate. 743 B4) Re-transmit the ASCONF Chunk last sent and if possible choose an 744 alternate destination address (please refer to RFC2960 [5] section 745 6.4.1). An endpoint MUST NOT add new parameters to this chunk, it 746 MUST be the same (including its serial number) as the last ASCONF 747 sent. 749 B5) Restart the T-4 RTO timer. Note that if a different destination 750 is selected, then the RTO used will be that of the new destination 751 address. 753 Note: the total number of re-transmissions is limited by B2 above. 754 If the maximum is reached, the association will fail and enter into 755 the CLOSED state (see RFC2960 [5] section 6.4.1 for details). 757 4.1.1 Congestion Control of ASCONF Chunks 759 In defining the ASCONF Chunk transfer procedures, it is essential 760 that these transfers MUST NOT cause congestion within the network. 761 To achieve this, we place these restrictions on the transfer of 762 ASCONF Chunks: 764 R1) One and only one ASCONF Chunk MAY be in transit and 765 unacknowledged at any one time. If a sender, after sending an 766 ASCONF chunk, decides it needs to transfer another ASCONF Chunk, 767 it MUST wait until the ASCONF-ACK Chunk returns from the previous 768 ASCONF Chunk before sending a subsequent ASCONF. Note this 769 restriction binds each side, so at any time two ASCONF may be 770 in-transit on any given association (one sent from each endpoint). 772 R2) An ASCONF may be bundled with any other chunk type (except other 773 ASCONF Chunks). 775 R3) An ASCONF-ACK may be bundled with any other chunk type except 776 other ASCONF-ACKs. 778 R4) Both ASCONF and ASCONF-ACK chunks MUST NOT be sent in any SCTP 779 state except ESTABLISHED. 781 R5) An ASCONF MUST NOT be larger than the path MTU of the 782 destination. 784 R6) An ASCONF-ACK SHOULD not be larger than the path MTU. In some 785 circumstances an ASCONF-ACK may exceed the path MTU and in such a 786 case IP fragmentation should be used to transmit the chunk. 788 If the sender of an ASCONF Chunk receives an Operational Error 789 indicating that the ASCONF chunk type is not understood, then the 790 sender MUST NOT send subsequent ASCONF Chunks to the peer. The 791 endpoint should also inform the upper layer application that the peer 792 endpoint does not support any of the extensions detailed in this 793 document. 795 4.2 Upon reception of an ASCONF Chunk. 797 When an endpoint receives an ASCONF Chunk from the remote peer 798 special procedures MAY be needed to identify the association the 799 ASCONF Chunk is associated with. To properly find the association 800 the following procedures should be followed: 802 L1) Use the source address and port number of the sender to attempt 803 to identify the association (i.e. use the same method defined in 804 RFC2960 [5] used for all other SCTP chunks). If found proceed to 805 rule L4. 807 L2) If the association is not found, use the address found in the 808 Address Parameter TLV combined with the port number found in the 809 SCTP common header. If found proceed to rule L4. 811 L3) If neither L1 or L2 locates the association, treat the chunk as 812 an Out Of The Blue chunk as defined in RFC2960 [5]. 814 L4) Follow the normal rules to validate the SCTP verification tag 815 found in RFC2960 [5]. 817 After identification and verification of the association, the 818 following should be performed to properly process the ASCONF Chunk: 820 C1) Compare the value of the serial number to the value the endpoint 821 stored in a new association variable 'Peer-Serial-Number'. This 822 value MUST be initialized to the Initial TSN value minus 1. 824 C2) If the value found in the serial number is equal to the 825 ('Peer-Serial-Number' + 1), the endpoint MUST: 827 V1) Process the TLVs contained within the Chunk performing the 828 appropriate actions as indicated by each TLV type. The TLVs 829 MUST be processed in order within the Chunk. For example, if 830 the sender puts 3 TLVs in one chunk, the first TLV (the one 831 closest to the Chunk Header) in the Chunk MUST be processed 832 first. The next TLV in the chunk (the middle one) MUST be 833 processed second and finally the last TLV in the Chunk MUST be 834 processed last. 836 V2) In processing the chunk, the receiver should build a response 837 message with the appropriate error TLVs, as specified in the 838 Parameter type bits for any ASCONF Parameter it does not 839 understand. To indicate an unrecognized parameter, cause type 840 8 as defined in the ERROR in 3.3.10.8 of RFC2960 [5] should be 841 used. The endpoint may also use the response to carry 842 rejections for other reasons such as resource shortages etc, 843 using the Error Cause TLV and an appropriate error condition. 845 Note: a positive response is implied if no error is indicated 846 by the sender. 848 V3) All responses MUST copy the ASCONF-Request Correlation ID 849 field received in the ASCONF parameter, from the TLV being 850 responded to, into the ASCONF-Request Correlation ID field in 851 the response parameter. 853 V4) After processing the entire Chunk, the receiver of the ASCONF 854 MUST send all TLVs for both unrecognized parameters and any 855 other status TLVs inside the ASCONF-ACK chunk that acknowledges 856 the arrival and processing of the ASCONF Chunk. 858 V5) Update the 'Peer-Serial-Number' to the value found in the 859 serial number field. 861 C3) If the value found in the serial number is equal to the value 862 stored in the 'Peer-Serial-Number', the endpoint should: 864 X1) Parse the ASCONF Chunk TLVs but the endpoint MUST NOT take any 865 action on the TLVs parsed (since it has already performed these 866 actions). 868 X2) Build a response message with the appropriate response TLVs as 869 specified in the ASCONF Parameter type bits, for any parameter 870 it does not understand or could not process. 872 X3) After parsing the entire Chunk, it MUST send any response TLV 873 errors and status with an ASCONF-ACK chunk acknowledging the 874 arrival and processing of the ASCONF Chunk. 876 X4) The endpoint MUST NOT update its 'Peer-Serial-Number'. 878 Note: the response to the retransmitted ASCONF MUST be the same as 879 the original response. This MAY mean an implementation must keep 880 state in order to respond with the same exact answer (including 881 resource considerations that may have made the implementation 882 refuse a request). 884 IMPLEMENTATION NOTE: As an optimization a receiver may wish to 885 save the last ASCONF-ACK for some predetermined period of time and 886 instead of re-processing the ASCONF (with the same serial number) 887 it may just re-transmit the ASCONF-ACK. It may wish to use the 888 arrival of a new serial number to discard the previously saved 889 ASCONF-ACK or any other means it may choose to expire the saved 890 ASCONF-ACK. 892 C4) Otherwise, the ASCONF Chunk is discarded since it must be either 893 a stale packet or from an attacker. A receiver of such a packet 894 MAY log the event for security purposes. 896 C5) In both cases C2 and C3 the ASCONF-ACK MUST be sent back to the 897 source address contained in the IP header of the ASCONF being 898 responded to. 900 4.3 General rules for address manipulation 902 When building TLV parameters for the ASCONF Chunk that will add or 903 delete IP addresses the following rules should be applied: 905 D0) If an endpoint receives an ASCONF-ACK that is greater than or 906 equal to the next sequence number to be used but no ASCONF chunk 907 is outstanding the endpoint MUST ABORT the association. Note that 908 a sequence number is greater than if it is no more than 2^^31-1 909 larger than the current sequence number (using serial arithmetic). 911 D1) When adding an IP address to an association, the IP address is 912 NOT considered fully added to the association until the ASCONF-ACK 913 arrives. This means that until such time as the ASCONF containing 914 the add is acknowledged the sender MUST NOT use the new IP address 915 as a source for ANY SCTP packet except on carrying an ASCONF 916 chunk. The receiver of the add IP address request may use the 917 address as a destination immediately. 919 D2) After the ASCONF-ACK of an IP address add arrives, the endpoint 920 MAY begin using the added IP address as a source address for any 921 type of SCTP chunk. 923 D3a) If an endpoint receives an Error Cause TLV indicating that the 924 IP address Add or IP address Deletion parameters was not 925 understood, the endpoint MUST consider the operation failed and 926 MUST NOT attempt to send any subsequent Add or Delete requests to 927 the peer. 929 D3b) If an endpoint receives an Error Cause TLV indicating that the 930 IP address Set Primary IP Address parameter was not understood, 931 the endpoint MUST consider the operation failed and MUST NOT 932 attempt to send any subsequent Set Primary IP Address requests to 933 the peer. 935 D4) When deleting an IP address from an association, the IP address 936 MUST be considered a valid destination address for the reception 937 of SCTP packets until the ASCONF-ACK arrives and MUST NOT be used 938 as a source address for any subsequent packets. This means that 939 any datagrams that arrive before the ASCONF-ACK destined to the IP 940 address being deleted MUST be considered part of the current 941 association. One special consideration is that ABORT chunks 942 arriving destined to the IP address being deleted MUST be ignored 943 (see Section 4.3.1 for further details). 945 D5) An endpoint MUST NOT delete its last remaining IP address from an 946 association. In other words if an endpoint is NOT multi-homed it 947 MUST NOT use the delete IP address without an add IP address 948 preceding the delete parameter in the ASCONF chunk. Or if an 949 endpoint sends multiple requests to delete IP addresses it MUST 950 NOT delete all of the IP addresses that the peer has listed for 951 the requester. 953 D6) An endpoint MUST NOT set an IP header source address for an SCTP 954 packet holding the ASCONF Chunk to be the same as an address being 955 deleted by the ASCONF Chunk. 957 D7) If a request is received to delete the last remaining IP address 958 of a peer endpoint, the receiver MUST send an Error Cause TLV with 959 the error cause set to the new error code 'Request to Delete Last 960 Remaining IP Address'. The requested delete MUST NOT be performed 961 or acted upon, other than to send the ASCONF-ACK. 963 D8) If a request is received to delete an IP address which is also 964 the source address of the IP packet which contained the ASCONF 965 chunk, the receiver MUST reject this request. To reject the 966 request the receiver MUST send an Error Cause TLV set to the new 967 error code 'Request to Delete Source IP Address' (unless Rule D5 968 has also been violated, in which case the error code 'Request to 969 Delete Last Remaining IP Address' is sent). 971 D9) If an endpoint receives an ADD IP address request and does not 972 have the local resources to add this new address to the 973 association, it MUST return an Error Cause TLV set to the new 974 error code 'Operation Refused Due to Resource Shortage'. 976 D10) If an endpoint receives an 'Out of Resource' error in response 977 to its request to ADD an IP address to an association, it must 978 either ABORT the association or not consider the address part of 979 the association. In other words if the endpoint does not ABORT 980 the association, it must consider the add attempt failed and NOT 981 use this address since its peer will treat SCTP packets destined 982 to the address as Out Of The Blue packets. 984 D11) When an endpoint receiving an ASCONF to add an IP address sends 985 an 'Out of Resource' in its response, it MUST also fail any 986 subsequent add or delete requests bundled in the ASCONF. The 987 receiver MUST NOT reject an ADD and then accept a subsequent 988 DELETE of an IP address in the same ASCONF Chunk. In other words, 989 once a receiver begins failing any ADD or DELETE request, it must 990 fail all subsequent ADD or DELETE requests contained in that 991 single ASCONF. 993 D12) When an endpoint receives a request to delete an IP address that 994 is the current primary address, it is an implementation decision 995 as to how that endpoint chooses the new primary address. 997 D13) When an endpoint receives a valid request to DELETE an IP 998 address the endpoint MUST consider the address no longer as part 999 of the association. It MUST NOT send SCTP packets for the 1000 association to that address and it MUST treat subsequent packets 1001 received from that address as Out Of The Blue. 1003 During the time interval between sending out the ASCONF and 1004 receiving the ASCONF-ACK it MAY be possible to receive DATA chunks 1005 out of order. The following examples illustrate these problems: 1007 Endpoint-A Endpoint-Z 1008 ---------- ---------- 1009 ASCONF[Add-IP:X]------------------------------> 1010 /--ASCONF-ACK 1011 / 1012 /--------/---New DATA: 1013 / / Destination 1014 <-------------------/ / IP:X 1015 / 1016 <--------------------------/ 1018 In the above example we see a new IP address (X) being added to the 1019 Endpoint-A. However due to packet re-ordering in the network a new 1020 DATA chunk is sent and arrives at Endpoint-A before the ASCONF-ACK 1021 confirming the add of the address to the association. 1023 A similar problem exists with the deletion of an IP address as 1024 follows: 1026 Endpoint-A Endpoint-Z 1027 ---------- ---------- 1028 /------------New DATA: 1029 / Destination 1030 / IP:X 1031 ASCONF [DEL-IP:X]---------/----------------> 1032 <-----------------/------------------ASCONF-ACK 1033 / 1034 / 1035 <-------------/ 1037 In this example we see a DATA chunk destined to the IP:X (which is 1038 about to be deleted) arriving after the deletion is complete. For 1039 the ADD case an endpoint SHOULD consider the newly adding IP address 1040 valid for the association to receive data from during the interval 1041 when awaiting the ASCONF-ACK. The endpoint MUST NOT source data from 1042 this new address until the ASCONF-ACK arrives but it may receive out 1043 of order data as illustrated and MUST NOT treat this data as an OOTB 1044 datagram (please see RFC2960 [5] section 8.4). It MAY drop the data 1045 silently or it MAY consider it part of the association but it MUST 1046 NOT respond with an ABORT. 1048 For the DELETE case, an endpoint MAY respond to the late arriving 1049 DATA packet as an OOTB datagram or it MAY hold the deleting IP 1050 address for a small period of time as still valid. If it treats the 1051 DATA packet as an OOTB the peer will silently discard the ABORT 1052 (since by the time the ABORT is sent the peer will have removed the 1053 IP address from this association). If the endpoint elects to hold 1054 the IP address valid for a period of time, it MUST NOT hold it valid 1055 longer than 2 RTO intervals for the destination being removed. 1057 4.3.1 A special case for OOTB ABORT chunks 1059 Another case worth mentioning is illustrated below: 1061 Endpoint-A Endpoint-Z 1062 ---------- ---------- 1064 New DATA:------------\ 1065 Source IP:X \ 1066 \ 1067 ASCONF-REQ[DEL-IP:X]----\------------------> 1068 \ /---------ASCONF-ACK 1069 \ / 1070 \----/-----------> OOTB 1071 (Ignored <---------------------/-------------ABORT 1072 by rule D4) / 1073 <---------------------/ 1075 For this case, during the deletion of an IP address, an Abort MUST be 1076 ignored if the destination address of the Abort message is that of a 1077 destination being deleted. 1079 4.3.2 A special case for changing an address. 1081 In some instances the sender may only have one IP address in an 1082 association that is being renumbered. When this occurs, the sender 1083 may not be able to send to the peer the appropriate ADD/DELETE pair 1084 and use the old address as a source in the IP header. For this 1085 reason the sender MUST fill in the Address Parameter field with an 1086 address that is part of the association (in this case the one being 1087 deleted). This will allow the receiver to locate the association 1088 without using the source address found in the IP header. 1090 The receiver of such a chunk MUST always first use the source address 1091 found in the IP header in looking up the association. The receiver 1092 should attempt to use the address found in the Address Bytes field 1093 only if the lookup fails using the source address from the IP header. 1094 The receiver MUST reply to the source address of the packet in this 1095 case which is the new address that was added by the ASCONF (since the 1096 old address is no longer a part of the association after processing). 1098 4.4 Setting of the primary address 1100 A sender of this option may elect to send this combined with a 1101 deletion or addition of an address. A sender SHOULD only send a set 1102 primary request to an address that is already considered part of the 1103 association. In other words if a sender combines a set primary with 1104 an add of a new IP address the set primary will be discarded unless 1105 the add request is to be processed BEFORE the set primary (i.e. it 1106 precedes the set primary). 1108 A request to set primary MAY also appear in an INIT or INIT-ACK 1109 chunk. This can give advice to the peer endpoint as to which of its 1110 addresses the sender of the INIT or INIT-ACK would prefer to be used 1111 as the primary address. 1113 The request to set an address as the primary path is an option the 1114 receiver SHOULD perform. It is considered advice to the receiver of 1115 the best destination address to use in sending SCTP packets (in the 1116 requesters view). If a request arrives that asks the receiver to set 1117 an address as primary that does not exist, the receiver should NOT 1118 honor the request, leaving its existing primary address unchanged. 1120 5. Security Considerations 1122 The ADD/DELETE of an IP address to an existing association does 1123 provide an additional mechanism by which existing associations can be 1124 hijacked. Where the attacker is able to intercept and or alter the 1125 packets sent and received in an association, the use of this feature 1126 MAY increase the ease with which an association may be overtaken. 1127 This threat SHOULD be considered when deploying a version of SCTP 1128 that makes use of this feature. The IP Authentication Header RFC2402 1129 [3] SHOULD be used when the threat environment requires stronger 1130 integrity protections, but does not require confidentiality. It 1131 should be noted that in the base SCTP specification RFC2960 [5], if 1132 an attacker is able to intercept and or alter packets, even without 1133 this feature it is possible to hijack an existing association; please 1134 refer to Section 11 of RFC2960 [5]. 1136 6. IANA considerations 1138 This document defines the following new SCTP parameters, chunks and 1139 errors: 1141 o Two new chunk types, 1143 o Six parameter types, and 1145 o Three new SCTP error causes. 1147 This document also defines a Adaption code point. The adaption code 1148 point is a 32 bit interger that is assigned by IANA through an IETF 1149 Consensus action as defined in RFC2434 [4]. 1151 7. Acknowledgments 1153 The authors wish to thank Jon Berger, Greg Kendall, Peter Lei, John 1154 Loughney, Ivan Arias Rodriguez, Renee Revis, Marshall Rose, and Chip 1155 Sharp for their invaluable comments. 1157 References 1159 [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 1160 9, RFC 2026, October 1996. 1162 [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement 1163 Levels", BCP 14, RFC 2119, March 1997. 1165 [3] Kent, S. and R. Atkinson, "IP Authentication Header", RFC 2402, 1166 November 1998. 1168 [4] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA 1169 Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. 1171 [5] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, 1172 H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson, 1173 "Stream Control Transmission Protocol", RFC 2960, October 2000. 1175 Authors' Addresses 1177 Randall R. Stewart 1178 Cisco Systems, Inc. 1179 8725 West Higgins Road 1180 Suite 300 1181 Chicago, IL 60631 1182 USA 1184 Phone: +1-815-477-2127 1185 EMail: rrs@cisco.com 1187 Michael A. Ramalho 1188 Cisco Systems, Inc. 1189 1802 Rue de la Porte 1190 Wall Township, NJ 07719-3784 1191 USA 1193 Phone: +1.732.449.5762 1194 EMail: mramalho@cisco.com 1195 Qiaobing Xie 1196 Motorola, Inc. 1197 1501 W. Shure Drive, #2309 1198 Arlington Heights, IL 60004 1199 USA 1201 Phone: +1-847-632-3028 1202 EMail: qxie1@email.mot.com 1204 Michael Tuexen 1206 Germany 1208 Phone: 1209 EMail: tuexen@fr-muenster.de 1211 Ian Rytina 1212 Ericsson 1213 37/360 Elizabeth Street 1214 Melbourne Victoria 1215 Australia 1217 Phone: +61-3-9301-6164 1218 EMail: ian.rytina@ericsson.com 1220 Maria-Carmen Belinchon 1221 Ericsson 1223 Spain 1225 Phone: 1226 EMail: emecbv@madrid.es.eu.ericsson.se 1228 Phillip T. Conrad 1229 Temple University 1230 CIS Department 1231 Room 303, Computer Building (038-24) 1232 1805 N. Broad St. 1233 Philadelphia, PA 19122 1234 US 1236 Phone: +1 215 204 7910 1237 EMail: conrad@acm.org 1238 URI: http://www.cis.temple.edu/~conrad 1240 Appendix A. Abstract Address Handling 1242 A.1 General remarks 1244 The following text provides a working definition of the endpoint 1245 notion to discuss address reconfiguration. It is not intended to 1246 restrict implementations in any way, its goal is to provide as set of 1247 definitions only. Using these definitions should make a discussion 1248 about address issues easier. 1250 A.2 Generalized endpoints 1252 A generalized endpoint is a pair of a set of IP addresses and a port 1253 number at any given point of time. The precise definition is as 1254 follows: 1256 A generalized endpoint gE at time t is given by 1258 gE(t) = ({IP1, ..., IPn}, Port) 1260 where {IP1, ..., IPn} is a non empty set of IP addresses. 1262 Please note that the dynamic addition and deletion of IP-addresses 1263 described in this document allows the set of IP-addresses of a 1264 generalized endpoint to be changed at some point of time. The port 1265 number can never be changed. 1267 The set of IP addresses of a generalized endpoint gE at a time t is 1268 defined as 1270 Addr(gE)(t) = {IP1, ..., IPn} 1272 if gE(t) = ({IP1, ..., IPn}, Port) holds at time t. 1274 The port number of a generalized endpoint gE is defined as 1276 Port(gE) = Port 1278 if gE(t) = ({IP1, ..., IPn}, Port) holds at time t. 1280 There is one fundamental rule which restricts all generalized 1281 endpoints: 1283 For two different generalized endpoints gE' and gE'' with the same 1284 port number Port(gE') = Port(gE'') the address sets Addr(gE')(t) and 1285 Addr(gE'')(t) must be disjoint at every point of time. 1287 A.3 Associations 1289 Associations consists of two generalized endpoints and the two 1290 address sets known by the peer at any time. The precise definition 1291 is as follows: 1293 An association A between to different generalized endpoints gE' and 1294 gE'' is given by 1296 A = (gE', S', gE'', S'') 1298 where S'(t) and S''(t) are set of addresses at any time t such that 1299 S'(t) is a non-empty subset of Addr(gE')(t) and S''(t) is a non-empty 1300 subset of Addr(gE'')(t). 1302 If A = (gE', S', gE'', S'') is an association between the generalized 1303 endpoints gE' and gE'' the following notion is used: 1305 Addr(A, gE') = S' and Addr(A, gE'') = S''. 1307 If the dependency on time is important the notion Addr(A, gE')(t) = 1308 S'(t) will be used. 1310 If A is an association between gE' and gE'' then Addr(A, gE') is the 1311 subset of IP addresses of gE' which is known by gE'' and used by gE'. 1313 Association establishment between gE' and gE'' can be seen as: 1315 1. gE' and gE'' do exist before the association. 1317 2. If an INIT has to be send from gE' to gE'' address scoping rules 1318 and other limitations are applied to calculate the subset S' from 1319 Addr(gE'). The addresses of S' are included in the INIT chunk. 1321 3. If an INIT-ACK has to be send from gE'' to gE' address scoping 1322 rules and other limitations are applied to calculate the subset 1323 S'' from Addr(gE''). The addresses of S'' are included in the 1324 INIT-ACK chunk. 1326 4. After the handshake the association A = (gE', S', gE'', S'') has 1327 been established. 1329 5. Right after the association establishment Addr(A, gE') and 1330 Addr(A, gE'') are the addresses which have been seen on the wire 1331 during the handshake. 1333 A.4 Relationship with RFC 2960 1335 RFC2960 [5] defines the notion of an endpoint. This subsection will 1336 show that these endpoints are also (special) generalized endpoints. 1338 RFC2960 [5] has no notion of address scoping or other address 1339 handling limitations and provides no mechanism to change the 1340 addresses of an endpoint. 1342 This means that an endpoint is simply a generalized endpoint which 1343 does not depend on the time. Neither the Port nor the address list 1344 changes. 1346 During association setup no address scoping rules or other 1347 limitations will be applied. This means that for an association A 1348 between two endpoints gE' and gE'' the following is true: 1350 Addr(A, gE') = Addr(gE') and Addr(A, gE'') = Addr(gE''). 1352 A.5 Rules for address manipulation 1354 The rules for address manipulation can now be stated in a simple way: 1356 1. An address can be added to a generalized endpoint gE only if this 1357 address is not an address of a different generalized endpoint 1358 with the same port number. 1360 2. An address can be added to an association A with generalized 1361 endpoint gE if it has been added to the generalized endpoint gE 1362 first. This means that the address must be an element of 1363 Addr(gE) first and then it can become an element of Addr(A, gE). 1364 But this is not necessary. If the association does not allow the 1365 reconfiguration of the addresses only Addr(gE) can be modified. 1367 3. An address can be deleted from an association A with generalized 1368 endpoint gE as long as Addr(A, gE) stays non-empty. 1370 4. An address can be deleted from an generalized endpoint gE only if 1371 it has been removed from all associations having gE as a 1372 generalized endpoint. 1374 These rules simply make sure that the rules for the endpoints and 1375 associations given above are always fulfilled. 1377 Intellectual Property Statement 1379 The IETF takes no position regarding the validity or scope of any 1380 intellectual property or other rights that might be claimed to 1381 pertain to the implementation or use of the technology described in 1382 this document or the extent to which any license under such rights 1383 might or might not be available; neither does it represent that it 1384 has made any effort to identify any such rights. Information on the 1385 IETF's procedures with respect to rights in standards-track and 1386 standards-related documentation can be found in BCP-11. Copies of 1387 claims of rights made available for publication and any assurances of 1388 licenses to be made available, or the result of an attempt made to 1389 obtain a general license or permission for the use of such 1390 proprietary rights by implementors or users of this specification can 1391 be obtained from the IETF Secretariat. 1393 The IETF invites any interested party to bring to its attention any 1394 copyrights, patents or patent applications, or other proprietary 1395 rights which may cover technology that may be required to practice 1396 this standard. Please address the information to the IETF Executive 1397 Director. 1399 Full Copyright Statement 1401 Copyright (C) The Internet Society (2003). All Rights Reserved. 1403 This document and translations of it may be copied and furnished to 1404 others, and derivative works that comment on or otherwise explain it 1405 or assist in its implementation may be prepared, copied, published 1406 and distributed, in whole or in part, without restriction of any 1407 kind, provided that the above copyright notice and this paragraph are 1408 included on all such copies and derivative works. However, this 1409 document itself may not be modified in any way, such as by removing 1410 the copyright notice or references to the Internet Society or other 1411 Internet organizations, except as needed for the purpose of 1412 developing Internet standards in which case the procedures for 1413 copyrights defined in the Internet Standards process must be 1414 followed, or as required to translate it into languages other than 1415 English. 1417 The limited permissions granted above are perpetual and will not be 1418 revoked by the Internet Society or its successors or assignees. 1420 This document and the information contained herein is provided on an 1421 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 1422 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 1423 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 1424 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 1425 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1427 Acknowledgement 1429 Funding for the RFC Editor function is currently provided by the 1430 Internet Society.