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'2' -- Obsolete informational reference (is this intentional?): RFC 2960 (ref. '4') (Obsoleted by RFC 4960) -- Obsolete informational reference (is this intentional?): RFC 2401 (ref. '7') (Obsoleted by RFC 4301) -- Obsolete informational reference (is this intentional?): RFC 2434 (ref. '9') (Obsoleted by RFC 5226) -- Obsolete informational reference (is this intentional?): RFC 3309 (ref. '10') (Obsoleted by RFC 4960) Summary: 7 errors (**), 0 flaws (~~), 8 warnings (==), 19 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group K. Morneault 2 Internet Draft Cisco Systems 3 Category: Standards Track S. Rengasami 4 Document: draft-ietf-sigtran-rfc3057bis-02.txt M. Kalla 5 Obsoletes RFC 3057 Telcordia Technologies 6 G. Sidebottom 7 Signatus Technologies 8 Expires August 2005 February 2005 10 ISDN Q.921-User Adaptation Layer 11 draft-ietf-sigtran-rfc3057bis-02.txt 13 Status of this Memo 15 This document is an Internet-Draft and is subject to all provisions 16 of Section 3 of RFC 3667. By submitting this Internet-Draft, each 17 author represents that any applicable patent or other IPR claims of 18 which he or she is aware have been or will be disclosed, and any of 19 which he or she become aware will be disclosed, in accordance with 20 RFC 3668. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as 25 Internet-Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt. 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html. 38 This Internet-Draft will expire August 2005. 40 Copyright Notice 42 Copyright (C) The Internet Society (2005). All Rights Reserved. 44 Abstract 46 This document defines a protocol for backhauling of ISDN Q.921 User 47 messages over IP using the Stream Control Transmission Protocol 48 (SCTP). This protocol would be used between a Signaling Gateway (SG) 49 and Media Gateway Controller (MGC). It is assumed that the SG 50 receives ISDN signaling over a standard ISDN interface. 52 This document obsoletes RFC 3057. 54 Table of Contents 56 1. Introduction................................................. 2 57 1.1 Scope..................................................... 2 58 1.2 Terminology............................................... 3 59 1.3 IUA Overview.............................................. 4 60 1.4 Services Provided by the IUA Layer........................ 9 61 1.5 Functions Implemented by the IUA Layer.................... 12 62 1.6 Definition of IUA Boundaries.............................. 14 63 2. Conventions.................................................. 16 64 3. Protocol Elements............................................ 17 65 3.1 Common Message Header..................................... 17 66 3.2 IUA Message Header........................................ 20 67 3.3 Description of Messages................................... 22 68 4. Procedures................................................... 45 69 4.1 Procedures to Support Service in Section 1.4.1............ 45 70 4.2 Procedures to Support Service in Section 1.4.2............ 46 71 4.3 Procedures to Support Service in Section 1.4.3............ 47 72 5. Examples...................................................... 53 73 5.1 Establishment of associations between SG and MGC examples.. 53 74 5.2 ASP Traffic Fail-over Examples............................. 55 75 5.3 Q.921/Q.931 primitives backhaul Examples................... 56 76 5.4 Layer Management Communication Examples.................... 58 77 6. Security..................................................... 58 78 7. IANA Considerations.......................................... 58 79 7.1 SCTP Payload Protocol Identifier........................... 58 80 7.2 IUA Protocol Extensions.................................... 58 81 8. Timer Values................................................. 60 82 9. Acknowledgements............................................. 60 83 10. References.................................................. 60 84 11. Change Log................................................... 61 85 12. Authors' Addresses........................................... 62 86 Appendix A....................................................... 63 88 1. Introduction 90 In this document, the term Q.921-User refers to an upper layer which 91 uses the services of Q.921, not the user side of ISDN interface [1]. 92 Examples of the upper layer would be Q.931 and QSIG. 94 This section describes the need for ISDN Q.921-User Adaptation (IUA) 95 layer protocol as well as how this protocol shall be implemented. 97 1.1 Scope 99 There is a need for Switched Circuit Network (SCN) signaling protocol 100 delivery from an ISDN Signaling Gateway (SG) to a Media Gateway 101 Controller (MGC) as described in the Framework Architecture for 102 Signaling Transport [5]. The delivery mechanism SHOULD meet the 103 following criteria: 105 * Support for transport of the Q.921 / Q.931 boundary primitives 106 * Support for communication between Layer Management modules on SG 107 and MGC 108 * Support for management of SCTP active associations between SG 109 and MGC 111 This document supports both ISDN Primary Rate Access (PRA) as well as 112 Basic Rate Access (BRA) including the support for both point-to-point 113 and point-to-multipoint modes of communication. This support 114 includes Facility Associated Signaling (FAS), Non-Facility Associated 115 Signaling (NFAS) and NFAS with backup D channel. QSIG adaptation 116 layer requirements do not differ from Q.931 adaptation layer, hence; 117 the procedures described in this document are also applicable for a 118 QSIG adaptation layer. For simplicity, only Q.931 will be mentioned 119 in the rest of this document. 121 1.2 Terminology 123 Application Server (AS) - A logical entity serving a specific 124 application instance. An example of an Application Server is a MGC 125 handling the Q.931 and call processing for D channels terminated by 126 the Signaling Gateways. Practically speaking, an AS is modeled at 127 the SG as an ordered list of one or more related Application Server 128 Processes (e.g., primary, secondary, tertiary). 130 Application Server Process (ASP) - A process instance of an 131 Application Server. Examples of Application Server Processes are 132 primary or backup MGC instances. 134 Association - An association refers to a SCTP association. The 135 association will provide the transport for the delivery of Q.921-User 136 protocol data units and IUA adaptation layer peer messages. 138 Backhaul - A SG terminates the lower layers of an SCN protocol and 139 backhauls the upper layer(s) to MGC for call processing. For the 140 purposes of this document the SG terminates Q.921 and backhauls Q.931 141 to MGC. 143 Fail-over - The capability to re-route signaling traffic as required 144 between related ASPs in the event of failure or unavailability of the 145 currently used ASP (e.g., from primary MGC to back-up MGC). Fail- 146 over also applies upon the return to service of a previously 147 unavailable process. 149 Host - The computing platform that the ASP process is running on. 151 Interface - For the purposes of this document an interface supports 152 the relevant ISDN signaling channel. This signaling channel MAY be a 153 16 kbps D channel for an ISDN BRA as well as 64 kbps primary or 154 backup D channel for an ISDN PRA. For QSIG, the signaling channel is 155 a Qc channel. 157 Interface Identifier - The Interface Identifier identifies the 158 physical interface at the SG for which the signaling messages are 159 sent/received. The format of the Interface Identifier parameter can 160 be text or integer, the values of which are assigned according to 161 network operator policy. The values used are of local significance 162 only, coordinated between the SG and ASP. Significance is not 163 implied across SGs served by an AS. 165 Layer Management - Layer Management is a nodal function that handles 166 the inputs and outputs between the IUA layer and a local management 167 entity. 169 Network Byte Order - Most significant byte first, a.k.a Big Endian. 171 Stream - A stream refers to an SCTP stream; a uni-directional logical 172 channel established from one SCTP endpoint to another associated SCTP 173 endpoint, within which all user messages are delivered in-sequence 174 except for those submitted to the un-ordered delivery service. 176 Q.921-User - Any protocol normally using the services of the ISDN 177 Q.921 (e.g., Q.931, QSIG, etc.). 179 1.3 IUA Overview 181 The architecture that has been defined [5] for SCN signaling 182 transport over IP uses multiple components, including an IP transport 183 protocol, a signaling common transport protocol and an adaptation 184 module to support the services expected by a particular SCN signaling 185 protocol from its underlying protocol layer. 187 This document defines an adaptation module that is suitable for the 188 transport of ISDN Q.921-User (e.g., Q.931) messages. 190 1.3.1 Example - SG to MGC 192 In a Signaling Gateway, it is expected that the ISDN signaling is 193 received over a standard ISDN network termination. The SG then 194 provides interworking of transport functions with IP Signaling 195 Transport, in order to transport the Q.931 signaling messages to the 196 MGC where the peer Q.931 protocol layer exists, as shown below: 198 ****** ISDN ****** IP ******* 199 * EP *---------------* SG *--------------* MGC * 200 ****** ****** ******* 202 +-----+ +-----+ 203 |Q.931| (NIF) |Q.931| 204 +-----+ +----------+ +-----+ 205 | | | | IUA| | IUA | 206 | | | +----+ +-----+ 207 |Q.921| |Q.921|SCTP| |SCTP | 208 | | | +----+ +-----+ 209 | | | | IP | | IP | 210 +-----+ +-----+----+ +-----+ 212 NIF - Nodal Interworking Function 213 EP - ISDN End Point 214 SCTP - Stream Control Transmission Protocol (Refer to [4,10]) 215 IUA - ISDN User Adaptation Layer Protocol 217 Figure 1 IUA in the SG to MGC Application 219 It is recommended that the IUA use the services of the Stream Control 220 Transmission Protocol (SCTP) as the underlying reliable common 221 signaling transport protocol. The use of SCTP provides the following 222 features: 224 - explicit packet-oriented delivery (not stream-oriented) 225 - sequenced delivery of user messages within multiple streams, 226 with an option for order-of-arrival delivery of individual user 227 messages, 228 - optional multiplexing of user messages into SCTP datagrams, 229 - network-level fault tolerance through support of multi-homing 230 at either or both ends of an association, 231 - resistance to flooding and masquerade attacks, and 232 - data segmentation to conform to discovered path MTU size 234 There are scenarios without redundancy requirements and scenarios in 235 which redundancy is supported below the transport layer. In these 236 cases, the SCTP functions above MAY be determined to not be required 237 and TCP MAY be used as the underlying common transport protocol. 239 1.3.2 Support for the management of SCTP associations between the SG 240 and ASPs 242 The IUA layer at the SG maintains the availability state of all 243 dynamically registered remote ASPs, in order to manage the SCTP 244 Associations and the traffic between the SG and ASPs. As well, the 245 active/inactive state of remote ASP(s) are also maintained. Active 246 ASPs are those currently receiving traffic from the SG. 248 The IUA layer MAY be instructed by local management to establish an 249 SCTP association to a peer IUA node. This can be achieved using the 250 M-SCTP ESTABLISH primitive to request, indicate and confirm the 251 establishment of an SCTP association with a peer IUA node. 253 The IUA layer MAY also need to inform local management of the status 254 of the underlying SCTP associations using the M-SCTP STATUS request 255 and indication primitive. For example, the IUA MAY inform local 256 management of the reason for the release of an SCTP association, 257 determined either locally within the IUA layer or by a primitive from 258 the SCTP. 260 1.3.3 ASP Fail-over Model and Terminology 262 The IUA layer supports ASP fail-over functions in order to support a 263 high availability of call processing capability. All Q.921-User 264 messages incoming to an SG are assigned to a unique Application 265 Server, based on the Interface Identifier of the message. 267 The Application Server is, in practical terms, a list of all ASPs 268 configured to process Q.921-User messages from certain Interface 269 Identifiers. One or more ASPs in the list are normally active (i.e., 270 handling traffic) while any others MAY be unavailable or inactive, to 271 be possibly used in the event of failure or unavailability of the 272 active ASP(s). 274 The IUA layer supports a n+k redundancy model (active-standby, load 275 sharing, broadcast) where n is the minimum number of redundant ASPs 276 required to handle traffic and k ASPs are available to take over for 277 a failed or unavailable ASP. Note that 1+1 active/standby redundancy 278 is a subset of this model. A simplex 1+0 model is also supported as 279 a subset, with no ASP redundancy. 281 1.3.4 Client/Server Model 283 It is recommended that the SG and ASP be able to support both client 284 and server operation. The peer endpoints using IUA SHOULD be 285 configured so that one always takes on the role of client and the 286 other the role of server for initiating SCTP associations. The 287 default orientation would be for the SG to take on the role of server 288 while the ASP is the client. In this case, ASPs SHOULD initiate the 289 SCTP association to the SG. 291 The SCTP and TCP Registered User Port Number Assignment for IUA is 292 9900. 294 1.4 Services Provided by the IUA Layer 296 1.4.1 Support for transport of Q.921/Q.931 boundary primitives 298 In the backhaul scenario, the Q.921/Q.931 boundary primitives are 299 exposed. IUA layer needs to support all of the primitives of this 300 boundary to successfully backhaul Q.931. 302 This includes the following primitives [1]: 304 DL-ESTABLISH 306 The DL-ESTABLISH primitives are used to request, indicate and confirm 307 the outcome of the procedures for establishing multiple frame 308 operation. 310 DL-RELEASE 312 DL-RELEASE primitives are used to request, indicate, and confirm the 313 outcome of the procedures for terminating a previously established 314 multiple frame operation, or for reporting an unsuccessful 315 establishment attempt. 317 DL-DATA 319 The DL-DATA primitives are used to request and indicate layer 3 320 (Q.931) messages which are to be transmitted, or have been received, 321 by the Q.921 layer using the acknowledged information transfer 322 service. 324 DL-UNIT DATA 326 The DL-UNIT DATA primitives are used to request and indicate layer 3 327 (Q.931) messages which are to be transmitted, by the Q.921 layer 328 using the unacknowledged information transfer service. 330 1.4.2 Support for communication between Layer Management modules on SG 331 and MGC 333 It is envisioned that the IUA layer needs to provide some services 334 that will facilitate communication between Layer Management modules 335 on the SG and MGC. These primitives are shown below: 337 M-TEI STATUS 339 The M-TEI STATUS primitives are used to request, confirm and indicate 340 the status (assigned/unassigned) of an ISDN Terminal Endpoint 341 Identifier (TEI). 343 M-ERROR 345 The M-ERROR primitive is used to indicate an error with a received 346 IUA message (e.g., interface identifier value is not known to the 347 SG). 349 1.4.3 Support for management of active associations between SG and MGC 351 A set of primitives between the IUA layer and the Layer Management 352 is defined below to help the Layer Management manage the SCTP 353 association(s) between the SG and MGC. The IUA layer can be 354 instructed by the Layer Management to establish an SCTP association 355 to a peer IUA node. This procedure can be achieved using the M-SCTP 356 ESTABLISH primitive. 358 M-SCTP ESTABLISH 360 The M-SCTP ESTABLISH primitives are used to request, indicate, and 361 confirm the establishment of an SCTP association to a peer IUA node. 363 M-SCTP RELEASE 365 The M-SCTP RELEASE primitives are used to request, indicate, and 366 confirm the release of an SCTP association to a peer IUA node. 368 The IUA layer MAY also need to inform the status of the SCTP 369 associations to the Layer Management. This can be achieved using the 370 M-SCTP STATUS primitive. 372 M-SCTP STATUS 374 The M-SCTP STATUS primitives are used to request and indicate the 375 status of the underlying SCTP association(s). 377 The Layer Management MAY need to inform the IUA layer of an AS/ASP 378 status (i.e., failure, active, etc.), so that messages can be 379 exchanged between IUA layer peers to stop traffic to the local IUA 380 user. This can be achieved using the M-ASP STATUS primitive. 382 M-ASP STATUS 384 The ASP status is stored inside IUA layer on both the SG and MGC 385 sides. The M-ASP STATUS primitive can be used by Layer Management to 386 request the status of the Application Server Process from the IUA 387 layer. This primitive can also be used to indicate the status of the 388 Application Server Process. 390 M-ASP-UP 392 The M-ASP-UP primitive can be used by Layer Management to send a ASP 393 Up message for the Application Server Process. It can also be used 394 to generate an ASP Up Acknowledgement. 396 M-ASP-DOWN 398 The M-ASP-DOWN primitive can be used by Layer Management to send a 399 ASP Down message for the Application Server Process. It can also be 400 used to generate an ASP Down Acknowledgement. 402 M-ASP-ACTIVE 404 The M-ASP-UP primitive can be used by Layer Management to send a ASP 405 Active message for the Application Server Process. It can also be 406 used to generate an ASP Active Acknowledgement. 408 M-ASP-INACTIVE 410 The M-ASP-UP primitive can be used by Layer Management to send a ASP 411 Inactive message for the Application Server Process. It can also be 412 used to generate an ASP Inactive Acknowledgement. 414 M-AS STATUS 416 The M-AS STATUS primitive can be used by Layer Management to request 417 the status of the Application Server. This primitive can also be 418 used to indicate the status of the Application Server. 420 1.5 Functions Implemented by the IUA Layer 422 1.5.1 Mapping 424 The IUA layer MUST maintain a map of the Interface Identifier to a 425 physical interface on the Signaling Gateway. A physical interface 426 would be a T1 line, E1 line, etc., and could include the TDM 427 timeslot. In addition, for a given interface the SG MUST be able to 428 identify the associated signaling channel. IUA layers on both SG and 429 MGC MAY maintain the status of ISDN TEIs (Terminal Endpoint Identifier) 430 and SAPIs (Service Access Point Identifier). 432 The SG maps an Interface Identifier to an SCTP association/stream 433 only when an ASP sends an ASP Active message for a particular 434 Interface Identifier. It MUST be noted, however, that this mapping 435 is dynamic and could change at any time due to a change of ASP state. 436 This mapping could even temporarily be invalid, for example during 437 failover of one ASP to another. Therefore, the SG MUST maintain the 438 states of AS/ASP and reference them during the routing of an messages 439 to an AS/ASP. 441 One example of the logical view of relationship between D channel, 442 Interface Identifier, AS and ASP in the SG is shown below: 444 /---------------------------------------------------+ 445 / /------------------------------------------------|--+ 446 / / v | 447 / / +----+ act+-----+ +-------+ -+--+-|+--+- 448 D chan1-------->|IID |-+ +-->| ASP |--->| Assoc | v 449 / +----+ | +----+ | +-----+ +-------+ -+--+--+--+- 450 / +->| AS |--+ Streams 451 / +----+ | +----+ stb+-----+ 452 D chan2-------->|IID |-+ | ASP | 453 +----+ +-----+ 455 where IID = Interface Identifier 457 Note that an ASP can be in more than one AS. 459 1.5.2 Status of ASPs 461 The IUA layer on the SG MUST maintain the state of the ASPs it is 462 supporting. The state of an ASP changes because of reception of 463 peer-to-peer messages (ASPM messages as described in Section 3.3.2) 464 or reception of indications from the local SCTP association. ASP 465 state transition procedures are described in Section 4.3.1. 467 At a SG, an Application Server list MAY contain active and inactive 468 ASPs to support ASP load-sharing and fail-over procedures. When, for 469 example, both a primary and a back-up ASP are available, IUA peer 470 protocol is required to control which ASP is currently active. The 471 ordered list of ASPs within a logical Application Server is kept 472 updated in the SG to reflect the active Application Server 473 Process(es). 475 Also the IUA layer MAY need to inform the local management of the 476 change in status of an ASP or AS. This can be achieved using the M- 477 ASP STATUS or M-AS STATUS primitives. 479 1.5.3 SCTP Stream Management 481 SCTP allows a user specified number of streams to be opened during 482 the initialization. It is the responsibility of the IUA layer to 483 ensure proper management of these streams. Because of the 484 unidirectional nature of streams, an IUA layer is not aware of the 485 stream number to Interface Identifier mapping of its peer IUA layer. 486 Instead, the Interface Identifier is in the IUA message header. 488 The use of SCTP streams within IUA is recommended in order to 489 minimize transmission and buffering delay, therefore improving the 490 overall performance and reliability of the signaling elements. It is 491 recommended that a separate SCTP stream is used for each D channel. 493 1.5.4 Seamless Network Management Interworking 495 The IUA layer on the SG SHOULD pass an indication of unavailability 496 of the IUA-User (Q.931) to the local Layer Management, if the 497 currently active ASP moves from the ACTIVE state. The Layer 498 Management could instruct Q.921 to take some action, if it deems 499 appropriate. 501 Likewise, if an SCTP association fails, the IUA layer on both the SG 502 and ASP sides MAY generate Release primitives to take the data links 503 out-of-service. 505 1.5.5 Congestion Management 507 If the IUA layer becomes congested (implementation dependent), it MAY 508 stop reading from the SCTP association to flow control from the peer 509 IUA. 511 1.6 Definition of IUA Boundaries 513 1.6.1 Definition of IUA/Q.921 boundary 515 DL-ESTABLISH 516 DL-RELEASE 517 DL-DATA 518 DL-UNIT DATA 520 1.6.2 Definition of IUA/Q.931 boundary 522 DL-ESTABLISH 523 DL-RELEASE 524 DL-DATA 525 DL-UNIT DATA 527 1.6.3 Definition of SCTP/IUA Boundary 529 An example of the upper layer primitives provided by SCTP are 530 available in Reference [4] section 10. 532 1.6.4 Definition of IUA/Layer-Management Boundary 534 M-SCTP ESTABLISH request 535 Direction: LM -> IUA 536 Purpose: LM requests ASP to establish an SCTP association with an SG. 538 M-STCP ESTABLISH confirm 539 Direction: IUA -> LM 540 Purpose: ASP confirms to LM that it has established an SCTP 541 association with an SG. 543 M-SCTP ESTABLISH indication 544 Direction: IUA -> LM 545 Purpose: SG informs LM that an ASP has established an SCTP 546 association. 548 M-SCTP RELEASE request 549 Direction: LM -> IUA 550 Purpose: LM requests ASP to release an SCTP association with SG. 552 M-SCTP RELEASE confirm 553 Direction: IUA -> LM 554 Purpose: ASP confirms to LM that it has released SCTP association 555 with SG. 557 M-SCTP RELEASE indication 558 Direction: IUA -> LM 559 Purpose: SG informs LM that ASP has released an SCTP association. 561 M-SCTP STATUS request 562 Direction: LM -> IUA 563 Purpose: LM requests IUA to report status of SCTP association. 565 M-SCTP STATUS indication 566 Direction: IUA -> LM 567 Purpose: IUA reports status of SCTP association. 569 M-ASP STATUS request 570 Direction: LM -> IUA 571 Purpose: LM requests SG to report status of remote ASP. 573 M-ASP STATUS indication 574 Direction: IUA -> LM 575 Purpose: SG reports status of remote ASP. 577 M-AS-STATUS request 578 Direction: LM -> IUA 579 Purpose: LM requests SG to report status of AS. 581 M-AS-STATUS indication 582 Direction: IUA -> LM 583 Purpose: SG reports status of AS. 585 M-NOTIFY indication 586 Direction: IUA -> LM 587 Purpose: ASP reports that it has received a NOTIFY message 588 from its peer. 590 M-ERROR indication 591 Direction: IUA -> LM 592 Purpose: ASP or SG reports that it has received an ERROR 593 message from its peer. 595 M-ASP-UP request 596 Direction: LM -> IUA 597 Purpose: LM requests ASP to start its operation and send an ASP UP 598 message to the SG. 600 M-ASP-UP confirm 601 Direction: IUA -> LM 602 Purpose: ASP reports that is has received an ASP UP Acknowledgement 603 message from the SG. 605 M-ASP-DOWN request 606 Direction: LM -> IUA 607 Purpose: LM requests ASP to stop its operation and send an ASP DOWN 608 message to the SG. 610 M-ASP-DOWN confirm 611 Direction: IUA -> LM 612 Purpose: ASP reports that is has received an ASP DOWN 613 Acknowledgement message from the SG. 615 M-ASP-ACTIVE request 616 Direction: LM -> IUA 617 Purpose: LM requests ASP to send an ASP ACTIVE message to the SG. 619 M-ASP-ACTIVE confirm 620 Direction: IUA -> LM 621 Purpose: ASP reports that is has received an ASP ACTIVE 622 Acknowledgement message from the SG. 624 M-ASP-INACTIVE request 625 Direction: LM -> IUA 626 Purpose: LM requests ASP to send an ASP INACTIVE message to the SG. 628 M-ASP-INACTIVE confirm 629 Direction: IUA -> LM 630 Purpose: ASP reports that is has received an ASP INACTIVE 631 Acknowledgement message from the SG. 633 M-TEI STATUS request 634 Direction: LM -> IUA 635 Purpose: LM requests ASP to send a TEI status request to the SG. 637 M-TEI STATUS indication 638 Direction: IUA -> LM 639 Purpose: ASP reports that is has received a TEI status indication 640 from the SG. 642 M-TEI STATUS confirm 643 Direction: IUA -> LM 644 Purpose: ASP reports that is has received a TEI status confirm from the 645 SG. 647 2.0 Conventions 649 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, 650 SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when 651 they appear in this document, are to be interpreted as described in 652 [RFC2119]. 654 3.0 Protocol Elements 656 This section describes the format of various messages used in this 657 protocol. 659 3.1 Common Message Header 661 The protocol messages for Q.921-User Adaptation require a message 662 header which contains the adaptation layer version, the message type, 663 and message length. 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 | Version | Reserved | Message Class | Message Type | 669 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 670 | Message Length | 671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 673 Figure 2 Common Header Format 675 All fields in an IUA message MUST be transmitted in the network byte 676 order, unless otherwise stated. 678 3.1.1 Version 680 The version field contains the version of the IUA adaptation layer. 681 The supported versions are the following: 683 Value Version 684 ----- ------- 685 1 Release 1.0 687 3.1.2 Message Classes and Types 689 The following List contains the valid Message Classes: 691 Message Class: 8 bits (unsigned integer) 693 0 Management (MGMT) Message [IUA/M2UA/M3UA/SUA] 694 1 Transfer Messages [M3UA] 695 2 SS7 Signalling Network Management (SSNM) Messages [M3UA/SUA] 696 3 ASP State Maintenance (ASPSM) Messages [IUA/M2UA/M3UA/SUA] 697 4 ASP Traffic Maintenance (ASPTM) Messages [IUA/M2UA/M3UA/SUA] 698 5 Q.921/Q.931 Boundary Primitives Transport (QPTM) 699 Messages [IUA] 700 6 MTP2 User Adaptation (MAUP) Messages [M2UA] 701 7 Connectionless Messages [SUA] 702 8 Connection-Oriented Messages [SUA] 703 9 to 127 Reserved by the IETF 704 128 to 255 Reserved for IETF-Defined Message Class extensions 706 The following list contains the message names for the defined 707 messages. 709 Q.921/Q.931 Boundary Primitives Transport (QPTM) Messages 711 0 Reserved 712 1 Data Request Message 713 2 Data Indication Message 714 3 Unit Data Request Message 715 4 Unit Data Indication Message 716 5 Establish Request 717 6 Establish Confirm 718 7 Establish Indication 719 8 Release Request 720 9 Release Confirm 721 10 Release Indication 722 11 to 127 Reserved by the IETF 723 128 to 255 Reserved for IETF-Defined QPTM extensions 725 Application Server Process State Maintenance (ASPSM) messages 727 0 Reserved 728 1 ASP Up (UP) 729 2 ASP Down (DOWN) 730 3 Heartbeat (BEAT) 731 4 ASP Up Ack (UP ACK) 732 5 ASP Down Ack (DOWN ACK) 733 6 Heatbeat Ack (BEAT ACK) 734 7 to 127 Reserved by the IETF 735 128 to 255 Reserved for IETF-Defined ASPSM extensions 737 Application Server Process Traffic Maintenance (ASPTM) messages 739 0 Reserved 740 1 ASP Active (ACTIVE) 741 2 ASP Inactive (INACTIVE) 742 3 ASP Active Ack (ACTIVE ACK) 743 4 ASP Inactive Ack (INACTIVE ACK) 744 5 to 127 Reserved by the IETF 745 128 to 255 Reserved for IETF-Defined ASPTM extensions 746 Management (MGMT) Messages 748 0 Error (ERR) 749 1 Notify (NTFY) 750 2 TEI Status Request 751 3 TEI Status Confirm 752 4 TEI Status Indication 753 5 TEI Query Request 754 6 to 127 Reserved by the IETF 755 128 to 255 Reserved for IETF-Defined MGMT extensions 757 3.1.3 Reserved 759 The Reserved field is 8-bits. It SHOULD be set to all '0's and 760 ignored by the receiver. 762 3.1.4 Message Length 764 The Message Length defines the length of the message in octets, 765 including the Common Header. The Message Length MUST include 766 parameter padding bytes, if any. 768 Note: A receiver SHOULD accept the message whether or not the final 769 parameter padding is included in the message length. 771 3.1.5 Variable-Length Parameter Format 773 IUA messages consist of a Common Header followed by zero or more 774 variable-length parameters, as defined by the message type. The 775 variable-length parameters contained in a message are defined in a 776 Tag-Length-Value format as shown below. 778 0 1 2 3 779 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 1 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | Parameter Tag | Parameter Length | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 \ \ 784 / Parameter Value / 785 \ \ 786 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 788 Mandatory parameters MUST be placed before optional parameters in a 789 message. 791 Parameter Tag: 16 bits (unsigned integer) 793 The Tag field is a 16-bit identifier of the type of parameter. It 794 takes a value of 0 to 65534. Common parameters used by adaptation 795 layers are in the range of 0x00 to 0x3f. The parameter Tags defined 796 are as follows: 798 Common Parameters. These TLV parameters are common across the 799 different adaptation layers: 801 Parameter Name Parameter ID 802 ============== ============ 803 Reserved 0x0000 804 Interface Identifier (integer) 0x0001 805 Not Used in IUA 0x0002 806 Interface Identifier (text) 0x0003 807 INFO String 0x0004 808 DLCI 0x0005 809 Not Used in IUA 0x0006 810 Diagnostic Information 0x0007 811 Interface Identifer Range 0x0008 812 Heartbeat Data 0x0009 813 Not Used in IUA 0x000a 814 Traffic Mode Type 0x000b 815 Error Code 0x000c 816 Status 0x000d 817 Protocol Data 0x000e 818 Release Reason 0x000f 819 TEI Status 0x0010 820 ASP Identifier 0x0011 821 Not Used in IUA 0x0012 - 0x003f 823 The value of 65535 is reserved for IETF-defined extensions. Values 824 other than those defined in specific parameter description are 825 reserved for use by the IETF. 827 Parameter Length: 16 bits (unsigned integer) 829 The Parameter Length field contains the size of the parameter in 830 bytes, including the Parameter Tag, Parameter Length, and Parameter 831 Value fields. The Parameter Length does not include any padding 832 bytes. 834 Parameter Value: variable-length 836 The Parameter Value field contains the actual information to be 837 transferred in the parameter. 839 The total length of a parameter (including Tag, Parameter Length and 840 Value fields) MUST be a multiple of 4 bytes. If the length of the 841 parameter is not a multiple of 4 bytes, the sender pads the Parameter 842 at the end (i.e., after the Parameter Value field) with all zero 843 bytes. The length of the padding is NOT included in the parameter 844 length field. A sender SHOULD NEVER pad with more than 3 bytes. The 845 receiver MUST ignore the padding bytes. 847 3.2 IUA Message Header 849 In addition to the common message header, there will be a specific 850 message header for QPTM and the TEI Status MGMT messages. The IUA 851 message header will immediately follow the Common header in these 852 messages. 854 This message header will contain the Interface Identifier and Data 855 Link Connection Identifier (DLCI). The Interface Identifier 856 identifies the physical interface terminating the signaling channel 857 at the SG for which the signaling messages are sent/received. The 858 format of the Interface Identifier parameter can be text or integer. 859 The Interface Identifiers are assigned according to network operator 860 policy. The integer values used are of local significance only, 861 coordinated between the SG and ASP. 863 The integer formatted Interface Identifier MUST be supported. The 864 text formatted Interface Identifier MAY optionally be supported. 866 0 1 2 3 867 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 1 868 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 869 | Tag (0x1) | Length | 870 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 871 | Interface Identifier (integer) | 872 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 873 | Tag (0x5) | Length=8 | 874 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 875 | DLCI | Spare | 876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 878 Figure 3 IUA Message Header (Integer-based Interface Identifier) 880 The Tag value for the Integer-based Interface Identifier is 0x1. The 881 length is always set to a value of 8. 883 0 1 2 3 884 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 1 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | Tag (0x3) | Length | 887 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 \ / 889 / Interface Identifier (text) \ 890 \ / 891 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 892 | Tag (0x5) | Length=8 | 893 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 894 | DLCI | Spare | 895 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 897 Figure 4 IUA Message Header (Text-based Interface Identifier) 899 The Tag value for the Text-based [2] Interface Identifier is 0x3. 900 The length is variable. 902 The DLCI format is shown below in Figure 5. 903 most least 904 significant significant 905 bit bit 906 +-----+-----+-----+-----+-----+-----+-----+-----+ 907 | SAPI | SPR | 0 | 908 +-----------------------------------------------+ 909 | TEI | 1 | 910 +-----------------------------------------------+ 912 Figure 5 DLCI Format 914 SPR: Spare 2nd bit in octet 1, (1 bit) 915 SAPI: Service Access Point Identifier, (6 bits) 917 TEI: Terminal Endpoint Identifier, (7 bits) 919 As an example SAPI = 0, TEI = 64, SPR = 0 would be encoded as 920 follows: 922 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 923 | Tag (0x5) | Length=8 | 924 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 925 | 0x0 | 0x81 | 0x0 | 926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 928 The DLCI field (including the SAPI and TEI) is coded in accordance 929 with Q.921. 931 3.3 IUA Messages 933 The following section defines the messages and parameter contents. 934 The IUA messages will use the common message header (Figure 2) and 935 the IUA message header (Figure 3 and Figure 4). 937 3.3.1 Q.921/Q.931 Boundary Primitives Transport (QPTM) Messages 939 3.3.1.1 Establish Messages (Request, Confirm, Indication) 941 The Establish Messages are used to establish a data link on the 942 signaling channel or to confirm that a data link on the signaling 943 channel has been established. The MGC controls the state of the D 944 channel. When the MGC desires the D channel to be in-service, it 945 will send the Establish Request message. 947 When the MGC sends an IUA Establish Request message, the MGC MAY 948 start a timer. This timer would be stopped upon receipt of an IUA 949 Establish Confirm or Establish Indication. If the timer expires, the 950 MGC would re-send the IUA Establish Request message and restart the 951 timer. In other words, the MGC MAY continue to request the 952 establishment of the data link on periodic basis until the desired 953 state is achieved or take some other action (notify the Management 954 Layer). 956 When the SG receives an IUA Establish Request from the MGC, the SG 957 shall send the Q.921 Establish Request primitive to the its Q.921 958 entity. In addition, the SG shall map any response received from the 959 Q.921 entity to the appropriate message to the MGC. For example, if 960 the Q.921 entity responds with a Q.921 Establish Confirm primitive, 961 the IUA layer shall map this to an IUA Establish Confirm message. As 962 another example, if the IUA Layer receives a Q.921 Release Confirm or 963 Release Indication as an apparent response to the Q.921 Establish 964 Request primitive, the IUA Layer shall map these to the corresponding 965 IUA Release Confirm or Release Indication messages. 967 The Establish messages contain the common message header followed by 968 IUA message header. It does not contain any additional parameters. 970 3.3.1.2 Release Messages (Request, Indication, Confirmation) 972 The Release Request message is used to release the data link on the 973 signaling channel. The Release Confirm and Indication messages are 974 used to indicate that the data link on the signaling channel has been 975 released. 977 If a response to the Release Request message is not received, the MGC 978 MAY resend the Release Request message. If no response is received, 979 the MGC can consider the data link as being released. In this case, 980 signaling traffic on that D channel is not expected from the SG and 981 signaling traffic will not be sent to the SG for that D channel. 983 The Release messages contain the common message header followed by 984 IUA message header. The Release confirm message is in response to a 985 Release Request message and it does not contain any additional 986 parameters. The Release Request and Indication messages contain the 987 following parameter: 989 Reason 991 The format for Release Message parameters is as follows: 993 0 1 2 3 994 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 1 995 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 996 | Tag (0xf) | Length | 997 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 998 | Reason | 999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1001 The valid values for Reason are shown in the following table. 1003 Define Value Description 1004 RELEASE_MGMT 0x0 Management layer generated release. 1005 RELEASE_PHYS 0x1 Physical layer alarm generated release. 1006 RELEASE_DM 0x2 Specific to a request. Indicates Layer 2 1007 SHOULD release and deny all requests from 1008 far end to establish a data link on the 1009 signaling channel (i.e., if SABME is 1010 received send a DM) 1011 RELEASE_OTHER 0x3 Other reasons 1013 Note: Only RELEASE_MGMT, RELEASE_DM and RELEASE_OTHER are valid 1014 reason codes for a Release Request message. 1016 3.3.1.3 Data Messages (Request, Indication) 1018 The Data message contains an ISDN Q.921-User Protocol Data Unit (PDU) 1019 corresponding to acknowledged information transfer service. 1021 The Data messages contain the common message header followed by IUA 1022 message header. The Data message contains the following parameter: 1024 Protocol Data 1026 The format for Data Message parameters is as follows: 1028 0 1 2 3 1029 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 1030 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 | Tag (0xe) | Length | 1032 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1033 \ \ 1034 / Protocol Data / 1035 \ \ 1036 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1038 The protocol data contains upper layer signaling message e.g. Q.931, 1039 QSIG. 1041 3.3.1.4 Unit Data Messages (Request, Indication) 1043 The Unit Data message contains an ISDN Q.921-User Protocol Data Unit 1044 (PDU) corresponding to unacknowledged information transfer service. 1046 The Unit Data messages contain the common message header followed by 1047 IUA message header. The Unit Data message contains the following 1048 parameter: 1050 Protocol Data 1052 The format for Unit Data Message parameters is as follows: 1054 0 1 2 3 1055 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 1056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1057 | Tag (0xe) | Length | 1058 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1059 \ \ 1060 / Protocol Data / 1061 \ \ 1062 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1064 3.3.2 Application Server Process Maintenance (ASPM) Messages 1066 The ASPM messages will only use the common message header. 1068 3.3.2.1 ASP Up (ASPUP) 1070 The ASP Up (ASPUP) message is sent by an ASP to indicate to an SG 1071 that it is ready to receive traffic or maintenance messages. 1073 The ASPUP message contains the following parameters: 1075 ASP Identifier (Optional) 1076 Info String (Optional) 1078 The format for ASPUP Message parameters is as follows: 1080 0 1 2 3 1081 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 1082 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1083 | Tag = 0x0011 | Length = 8 | 1084 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1085 | ASP Identifier | 1086 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1087 | Tag = 0x0004 | Length | 1088 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1089 \ \ 1090 / INFO String / 1091 \ \ 1092 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1094 ASP Identifier: 32-bit unsigned integer 1096 The optional ASP Identifier parameter contains a unique value that 1097 is locally significant among the ASPs that support an AS. The SG 1098 should save the ASP Identifier to be used, if necessary, with the 1099 Notify message (see Section 3.8.2). 1101 The optional INFO String parameter can carry any meaningful 8-bit 1102 ASCII [2] character string along with the message. Length of the 1103 INFO String parameter is from 0 to 255 characters. No procedures 1104 are presently identified for its use but the INFO String MAY be used 1105 for debugging purposes. 1107 3.3.2.2 ASP Up Ack 1109 The ASP Up Ack message is used to acknowledge an ASP Up message 1110 received from a remote IUA peer. 1112 The ASPUP Ack message contains the following parameters: 1114 INFO String (optional) 1116 The format for ASPUP Ack Message parameters is as follows: 1118 0 1 2 3 1119 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 1120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1121 | Tag = 0x0004 | Length | 1122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1123 \ \ 1124 / INFO String / 1125 \ \ 1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1128 The format and description of the optional INFO String parameter 1129 is the same as for the ASP Up message (See Section 3.3.3.1). 1131 3.3.2.3 ASP Down (ASPDN) 1133 The ASP Down (ASPDN) message is sent by an ASP to indicate to an SG 1134 that it is NOT ready to receive traffic or maintenance messages. 1136 The ASPDN message contains the following parameters: 1138 INFO String (Optional) 1140 The format for the ASPDN message parameters is as follows: 1142 0 1 2 3 1143 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 1144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1145 | Tag = 0x0004 | Length | 1146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1147 \ \ 1148 / INFO String / 1149 \ \ 1150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1152 The format and description of the optional INFO String parameter is 1153 the same as for the ASP Up message (See Section 3.3.2.1). 1155 3.3.2.4 ASP Down Ack 1157 The ASP Down Ack message is used to acknowledge an ASP Down message 1158 received from a remote IUA peer. 1160 The ASP Down Ack message contains the following parameters: 1162 INFO String (Optional) 1164 The format for the ASP Down Ack message parameters is as follows: 1166 0 1 2 3 1167 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 1168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1169 | Tag = 0x0004 | Length | 1170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1171 \ \ 1172 / INFO String / 1173 \ \ 1174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1176 The format and description of the optional Info String parameter is 1177 the same as for the ASP Up message (See Section 3.3.2.1). 1179 3.3.2.5 ASP Active (ASPAC) 1181 The ASPAC message is sent by an ASP to indicate to an SG that it is 1182 Active and ready to be used. 1184 The ASPAC message contains the following parameters 1186 Traffic Mode Type (Mandatory) 1187 Interface Identifiers (Optional) 1188 - Combination of integer and integer ranges, OR 1189 - string (text formatted) 1190 INFO String (Optional) 1192 The format for the ASPAC message using integer formatted Interface 1193 Identifiers is as follows: 1195 0 1 2 3 1196 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 1197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1198 | Tag = 0x000b | Length = 8 | 1199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1200 | Traffic Mode Type | 1201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1202 | Tag (0x1=integer) | Length | 1203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1204 \ \ 1205 / Interface Identifiers / 1206 \ \ 1207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1208 | Tag (0x8=integer range) | Length | 1209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1210 | Interface Identifier Start1* | 1211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1212 | Interface Identifier Stop1* | 1213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1214 | Interface Identifier Start2* | 1215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1216 | Interface Identifier Stop2* | 1217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1218 . . 1219 . . 1220 . . 1221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1222 | Interface Identifier StartN* | 1223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1224 | Interface Identifier StopN* | 1225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1226 \ \ 1227 / Additional Interface Identifier Parameters / 1228 \ of Tag Type 0x1 or 0x8 \ 1229 / / 1230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1231 | Tag (0x4) | Length | 1232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1233 \ \ 1234 / INFO String / 1235 \ \ 1236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1237 The format for the ASPAC message using text formatted (string) 1238 Interface Identifiers is as follows: 1240 0 1 2 3 1241 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 1242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1243 | Tag = 0x000b | Length = 8 | 1244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1245 | Traffic Mode Type | 1246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1247 | Tag (0x3=string) | Length | 1248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1249 \ \ 1250 / Interface Identifiers / 1251 \ \ 1252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1253 \ \ 1254 / Additional Interface Identifier Parameters / 1255 \ of Tag Type 0x3 \ 1256 / / 1257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1258 | Tag (0x4) | Length | 1259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 \ \ 1261 / INFO String / 1262 \ \ 1263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1265 The Traffic Mode Type parameter identifies the traffic mode of 1266 operation of the ASP within an AS. The valid values for Type are 1267 shown in the following table: 1269 Value Description 1270 0x1 Over-ride 1271 0x2 Load-share 1273 Within a particular AS, only one Traffic Mode Type can be used. 1274 The Over-ride value indicates that the ASP is operating 1275 in Over-ride mode, where the ASP takes over all traffic in an 1276 Application Server (i.e., primary/back-up operation), over-riding any 1277 currently active ASPs in the AS. In Load-share mode, the ASP will 1278 share in the traffic distribution with any other currently active 1279 ASPs. 1281 The optional Interface Identifiers parameter contains a list of 1282 Interface Identifier integers (Type 0x1 or Type 0x8) or text strings 1283 (Type 0x3) indexing the Application Server traffic that the sending 1284 ASP is configured/registered to receive. If integer formatted 1285 Interface Identifiers are being used, the ASP can also send ranges of 1286 Interface Identifiers (Type 0x8). Interface Identifier types Integer 1287 (0x1) and Integer Range (0x8) are allowed in the same message. Text 1288 formatted Interface Identifiers (0x3) cannot be used with either 1289 Integer (0x1) or Integer Range (0x8) types. 1291 If no Interface Identifiers are included, the message is for all 1292 provisioned Interface Identifiers within the AS(s) in which the ASP 1293 is provisioned. If only a subset of Interface Identifiers are 1294 included, the ASP is noted as Active for all the Interface 1295 Identifiers provisioned for that AS. 1297 Note: If the optional Interface Identifier parameter is present, the 1298 integer formatted Interface Identifier MUST be supported, while the 1299 text formatted Interface Identifier MAY be supported. 1301 The format and description of the optional Info String parameter is 1302 the same as for the ASP Up message (See Section 3.3.2.1.). 1304 An SG that receives an ASPAC with an incorrect Traffic Mode Type for 1305 a particular Interface Identifier will respond with an Error Message 1306 (Cause: Unsupported Traffic Handling Mode). 1308 3.3.2.6 ASP Active Ack 1310 The ASPAC Ack message is used to acknowledge an ASP-Active message 1311 received from a remote IUA peer. 1313 The ASPAC Ack message contains the following parameters: 1315 Traffic Mode Type (Mandatory) 1316 Interface Identifier (Optional) 1317 - Combination of integer and integer ranges, OR 1318 - string (text formatted) 1319 INFO String (Optional) 1321 The format for the ASPAC Ack message with Integer-formatted Interface 1322 Identifiers is as follows: 1324 0 1 2 3 1325 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 1326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1327 | Tag = 0x000b | Length = 8 | 1328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1329 | Traffic Mode Type | 1330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1331 | Tag (0x1=integer) | Length | 1332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1333 \ \ 1334 / Interface Identifiers / 1335 \ \ 1336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1337 | Tag (0x8=integer range) | Length | 1338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1339 | Interface Identifier Start1* | 1340 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1341 | Interface Identifier Stop1* | 1342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1343 | Interface Identifier Start2* | 1344 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1345 | Interface Identifier Stop2* | 1346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1347 . . 1348 . . 1349 . . 1350 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1351 | Interface Identifier StartN* | 1352 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1353 | Interface Identifier StopN* | 1354 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1355 \ \ 1356 / Additional Interface Identifier Parameters / 1357 \ of Tag Type 0x1 or 0x8 \ 1358 / / 1359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1360 | Tag (0x4) | Length | 1361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1362 \ \ 1363 / INFO String / 1364 \ \ 1365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1366 The format for the ASP Active Ack message using text formatted 1367 (string) Interface Identifiers is as follows: 1369 0 1 2 3 1370 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 1371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1372 | Tag = 0x000b | Length = 8 | 1373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1374 | Traffic Mode Type | 1375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1376 | Tag (0x3=string) | Length | 1377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1378 \ \ 1379 / Interface Identifiers / 1380 \ \ 1381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1382 \ \ 1383 / Additional Interface Identifier Parameters / 1384 \ of Tag Type 0x3 \ 1385 / / 1386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1387 | Tag (0x4) | Length | 1388 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1389 \ \ 1390 / INFO String / 1391 \ \ 1392 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1394 The format of the Traffic Mode Type and Interface Identifier 1395 parameters is the same as for the ASP Active message (See Section 1396 3.3.2.5). 1398 The format and description of the optional Info String parameter is 1399 the same as for the ASP Up message (See Section 3.3.2.1.). 1401 3.3.2.7 ASP Inactive (ASPIA) 1403 The ASPIA message is sent by an ASP to indicate to an SG that it is 1404 no longer an active ASP to be used from within a list of ASPs. The 1405 SG will respond with an ASPIA Ack message and either discard incoming 1406 messages or buffer for a timed period and then discard. 1408 The ASPIA message contains the following parameters 1410 Interface Identifiers (Optional) 1411 - Combination of integer and integer ranges, OR 1412 - string (text formatted) 1414 INFO String (Optional) 1416 The format for the ASP Inactive message parameters using Integer 1417 formatted Interface Identifiers is as follows: 1419 0 1 2 3 1420 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 1421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1422 | Tag (0x1=integer) | Length | 1423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1424 \ \ 1425 / Interface Identifiers / 1426 \ \ 1427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1428 | Tag (0x8=integer range) | Length | 1429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1430 | Interface Identifier Start1* | 1431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1432 | Interface Identifier Stop1* | 1433 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1434 | Interface Identifier Start2* | 1435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1436 | Interface Identifier Stop2* | 1437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1438 . . 1439 . . 1440 . . 1441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1442 | Interface Identifier StartN* | 1443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1444 | Interface Identifier StopN* | 1445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1446 \ \ 1447 / Additional Interface Identifier Parameters / 1448 \ of Tag Type 0x1 or 0x8 \ 1449 / / 1450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1451 | Tag (0x4) | Length | 1452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1453 \ \ 1454 / INFO String / 1455 \ \ 1456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1457 The format for the ASP Inactive message using text formatted (string) 1458 Interface Identifiers is as follows: 1460 0 1 2 3 1461 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 1462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1463 | Tag (0x3=string) | Length | 1464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1465 \ \ 1466 / Interface Identifiers / 1467 \ \ 1468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1469 \ \ 1470 / Additional Interface Identifier Parameters / 1471 \ of Tag Type 0x3 \ 1472 / / 1473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1474 | Tag (0x4) | Length | 1475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1476 \ \ 1477 / INFO String / 1478 \ \ 1479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1481 The optional Interface Identifiers parameter contains a list of 1482 Interface Identifier integers or text strings indexing the 1483 Application Server traffic that the sending ASP is configured/- 1484 registered to receive, but does not want to receive at this time. 1486 The format and description of the optional Interface Identifiers and 1487 INFO String parameters are the same as for the ASP Active message 1488 (See Section 3.3.2.3.). 1490 3.3.2.8 ASP Inactive Ack 1492 The ASP Inactive (ASPIA) Ack message is used to acknowledge an ASP 1493 Inactive message received from a remote IUA peer. 1495 The ASPIA Ack message contains the following parameters: 1497 Interface Identifiers (Optional) 1498 - Combination of integer and integer ranges, OR 1499 - string (text formatted) 1500 INFO String (Optional) 1502 The format for the ASP Inactive Ack message parameters using Integer 1503 formatted Interface Identifiers is as follows: 1505 0 1 2 3 1506 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 1507 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1508 | Tag (0x1=integer) | Length | 1509 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1510 \ \ 1511 / Interface Identifiers / 1512 \ \ 1513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1514 | Tag (0x8=integer range) | Length | 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 | Interface Identifier Start1* | 1517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1518 | Interface Identifier Stop1* | 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | Interface Identifier Start2* | 1521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1522 | Interface Identifier Stop2* | 1523 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1524 . . 1525 . . 1526 . . 1527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1528 | Interface Identifier StartN* | 1529 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1530 | Interface Identifier StopN* | 1531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1532 \ \ 1533 / Additional Interface Identifier Parameters / 1534 \ of Tag Type 0x1 or 0x8 \ 1535 / / 1536 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1537 | Tag (0x4) | Length | 1538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1539 \ \ 1540 / INFO String / 1541 \ \ 1542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1543 The format for the ASP Inactive Ack message using text formatted 1544 (string) Interface Identifiers is as follows: 1546 0 1 2 3 1547 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 1548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1549 | Tag (0x3=string) | Length | 1550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1551 \ \ 1552 / Interface Identifiers / 1553 \ \ 1554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1555 \ \ 1556 / Additional Interface Identifier Parameters / 1557 \ of Tag Type 0x3 \ 1558 / / 1559 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1560 | Tag (0x4) | Length | 1561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1562 \ \ 1563 / INFO String / 1564 \ \ 1565 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1567 The format and description of the optional Interface Identifiers and 1568 INFO String parameters are the same as for the ASP Active message 1569 (See Section 3.3.2.3.). 1571 3.3.2.9 Heartbeat (BEAT) 1573 The Heartbeat message is optionally used to ensure that the IUA peers 1574 are still available to each other. It is recommended for use when 1575 the IUA runs over a transport layer other than the SCTP, which has 1576 its own heartbeat. 1578 The BEAT message contains the following parameters: 1580 Heartbeat Data (Optional) 1582 The format for the BEAT message is as follows: 1584 0 1 2 3 1585 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 1586 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1587 | Tag = 0x0009 | Length | 1588 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1589 \ \ 1590 / Heartbeat Data / 1591 \ \ 1592 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1594 The Heartbeat Data parameter contents are defined by the sending 1595 node. The Heartbeat Data could include, for example, a Heartbeat 1596 Sequence Number and, or Timestamp. The receiver of a Heartbeat 1597 message does not process this field as it is only of significance to 1598 the sender. The receiver MUST respond with a Heartbeat Ack message. 1600 3.3.2.10 Heartbeat Ack (BEAT-Ack) 1602 The Heartbeat Ack message is sent in response to a received Heartbeat 1603 message. It includes all the parameters of the received Heartbeat 1604 message, without any change. 1606 3.3.3 Layer Management (MGMT) Messages 1608 3.3.3.1 Error (ERR) 1610 The Error message is used to notify a peer of an error event 1611 associated with an incoming message. For example, the message type 1612 might be unexpected given the current state, or a parameter value 1613 might be invalid. 1615 The Error message will only have the common message header. The 1616 Error message contains the following parameters: 1618 Error Code 1619 Diagnostic Information (optional) 1621 0 1 2 3 1622 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 1623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1624 | Tag = 0x000c | Length = 8 | 1625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1626 | Error Code | 1627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1628 | Tag = 0x0007 | Length | 1629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1630 \ / 1631 / Diagnostic Information \ 1632 \ / 1633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1635 The Error Code parameter indicates the reason for the Error Message. 1636 The Error parameter value can be one of the following values: 1638 Invalid Version 0x01 1639 Invalid Interface Identifier 0x02 1640 Unsupported Message Class 0x03 1641 Unsupported Message Type 0x04 1642 Unsupported Traffic Handling Mode 0x05 1643 Unexpected Message 0x06 1644 Protocol Error 0x07 1645 Unsupported Interface Identifier Type 0x08 1646 Invalid Stream Identifier 0x09 1647 Unassigned TEI 0x0a 1648 Unrecognized SAPI 0x0b 1649 Invalid TEI, SAPI combination 0x0c 1650 Refused - Management Blocking 0x0d 1651 ASP Identifier Required 0x0e 1652 Invalid ASP Identifier 0x0f 1654 The "Invalid Version" error would be sent if a message was received 1655 with an invalid or unsupported version. The Error message would 1656 contain the supported version in the Common header. The Error 1657 message could optionally provide the supported version in the 1658 Diagnostic Information area. 1660 The "Invalid Interface Identifier" error would be sent by a SG if an 1661 ASP sends a message with an invalid (unconfigured) Interface 1662 Identifier value. For this error, the Diagnostic Information MUST 1663 contain enough of the offending message to identify the invalid 1664 Interface Identifier. For example, in the case of QPTM and TEI 1665 Status management messages, the Common and IUA message headers of 1666 the offending message would be place in the Diagnostic Information 1667 at a minimum. 1669 The "Unsupported Traffic Handling Mode" error would be sent by a SG 1670 if an ASP sends an ASP Active with an unsupported Traffic Handling 1671 Mode. An example would be a case in which the SG did not support 1672 load-sharing. 1674 The "Unexpected Message" error would be sent by an ASP if it received 1675 a QPTM message from an SG while it was in the Inactive state (the ASP 1676 could optionally drop the message and not send an Error). It would 1677 also be sent by an ASP if it received a defined and recognized 1678 message that the SG is not expected to send (e.g., if the MGC 1679 receives an IUA Establish Request message). 1681 The "Protocol Error" error would be sent for any protocol anomaly 1682 (i.e., a bogus message). 1684 The "Invalid Stream Identifier" error would be sent if a message was 1685 received on an unexpected SCTP stream (e.g., a MGMT message was 1686 received on a stream other than "0"). 1688 The "Unsupported Interface Identifier Type" error would be sent by a 1689 SG if an ASP sends a Text formatted Interface Identifier and the SG 1690 only supports Integer formatted Interface Identifiers. When the ASP 1691 receives this error, it will need to resend its message with an 1692 Integer formatted Interface Identifier. 1694 The "Unsupported Message Type" error would be sent if a message with 1695 an unexpected or unsupported Message Type is received. 1697 The "Unsupported Message Class" error would be sent if a message with 1698 an unexpected or unsupported Message Class is received. 1700 The "Unassigned TEI" error may be used when the SG receives an IUA 1701 message that includes a TEI which has not been assigned or recognized 1702 for use on the indicated ISDN D-channel. 1704 The "Unrecognized SAPI" error would handle the case of using a SAPI 1705 that is not recognized by the SG. The "Invalid TEI, SAPI 1706 combination" error identify errors where the TEI is assigned and the 1707 the SAPI is recognized, but the combination is not valid for the 1708 interface (e.g., on a BRI the MGC tries to send Q.921 Management 1709 messages via IUA when Layer Management at the SG SHOULD be performing 1710 this function). 1712 The "Refused - Management Blocking" error is sent when an ASP Up or 1713 ASP Active message is received and the request is refused for 1714 management reasons (e.g., management lockout"). 1716 The "ASP Identifier Required" is sent by a SG in response 1717 to an ASP Up message which does not contain an ASP Identifier 1718 parameter when the SG requires one. The ASP SHOULD resend the 1719 ASP Up message with an ASP Identifier. 1721 The "Invalid ASP Identifier" is send by a SG in response 1722 to an ASP Up message with an invalid (i.e., non-unique) ASP 1723 Identifier. 1725 Diagnostic Information: variable length 1727 When included, the optional Diagnostic information can be any 1728 information germane to the error condition, to assist in 1729 identification of the error condition. The Diagnostic information 1730 SHOULD contain the offending message. 1732 Error messages MUST NOT be generated in response to other Error 1733 messages. 1735 3.3.3.2 Notify (NTFY) 1737 The Notify message used to provide an autonomous indication of IUA 1738 events to an IUA peer. 1740 The Notify message will only use the common message header. The 1741 Notify message contains the following parameters: 1743 Status (Mandatory) 1744 ASP Identifier (Optional) 1745 Interface Identifiers (Optional) 1746 INFO String (Optional) 1748 The format for the Notify message with Integer-formatted Interface 1749 Identifiers is as follows: 1751 0 1 2 3 1752 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 1753 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1754 | Tag = 0x000d | Length = 8 | 1755 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1756 | Status Type | Status Identification | 1757 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1758 | Tag = 0x0011 | Length = 8 | 1759 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1760 | ASP Identifier | 1761 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1762 | Tag (0x1=integer) | Length | 1763 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1764 \ \ 1765 / Interface Identifiers / 1766 \ \ 1767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1768 | Tag (0x8=integer range) | Length | 1769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1770 | Interface Identifier Start1* | 1771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1772 | Interface Identifier Stop1* | 1773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1774 | Interface Identifier Start2* | 1775 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1776 | Interface Identifier Stop2* | 1777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1778 . . 1779 . . 1780 . . 1781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1782 | Interface Identifier StartN* | 1783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1784 | Interface Identifier StopN* | 1785 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1786 \ \ 1787 / Additional Interface Identifier Parameters / 1788 \ of Tag Type 0x1 or 0x8 \ 1789 / / 1790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1791 | Tag = 0x0004 | Length | 1792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1793 \ \ 1794 / INFO String / 1795 \ \ 1796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1797 The format for the Notify message with Text-formatted Interface 1798 Identifiers is as follows: 1800 0 1 2 3 1801 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 1802 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1803 | Tag = 0x000d | Length = 8 | 1804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1805 | Status Type | Status Identification | 1806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1807 | Tag = 0x0011 | Length = 8 | 1808 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1809 | ASP Identifier | 1810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1811 | Tag (0x3=string) | Length | 1812 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1813 \ \ 1814 / Interface Identifiers / 1815 \ \ 1816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1817 \ \ 1818 / Additional Interface Identifier Parameters / 1819 \ of Tag Type 0x3 \ 1820 / / 1821 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1822 | Tag = 0x0004 | Length | 1823 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1824 \ \ 1825 / INFO String / 1826 \ \ 1827 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1829 Status Type: 16-bits (unsigned integer) 1831 The Status Type parameter identifies the type of the Notify 1832 message. The following are the valid Status Type values: 1834 1 Application Server State Change (AS-State_Change) 1835 2 Other 1837 Status Information: 16-bits (unsigned integer) 1839 The Status Information parameter contains more detailed 1840 information for the notification, based on the value of the Status 1841 Type. If the Status Type is AS-State_Change the following Status 1842 Information values are used: 1844 1 reserved 1845 2 Application Server Inactive (AS-INACTIVE) 1846 3 Application Server Active (AS-ACTIVE) 1847 4 Application Server Pending (AS-PENDING) 1849 These notifications are sent from an SG to an ASP upon a change in 1850 status of a particular Application Server. The value reflects the 1851 new state of the Application Server. 1853 If the Status Type is Other, then the following Status Information 1854 values are defined: 1856 Value Description 1857 1 Insufficient ASP resources active in AS 1858 2 Alternate ASP Active 1859 3 ASP Failure 1861 These notifications are not based on the SG reporting the state 1862 change of an ASP or AS. In the Insufficient ASP Resources case, the 1863 SG is indicating to an ASP-INACTIVE ASP(s) in the AS that another ASP 1864 is required in order to handle the load of the AS (Load-sharing 1865 mode). For the Alternate ASP Active case, an ASP is informed when an 1866 alternate ASP transitions to the ASP-ACTIVE state in Over-ride mode. 1867 The ASP Identifier (if available) of the Alternate ASP MUST be placed 1868 in the message. For the ASP Failure case, the SG is indicating to 1869 ASP(s) in the AS that one of the ASPs has transitioned to ASP-DOWN. 1870 The ASP Identifier (if available) of the failed ASP MUST be placed in 1871 the message. 1873 The format and description of the optional ASP Identifier are the 1874 same as for the ASP Up message (See Section 3.3.2.1). The format 1875 and description of the optional Interface Identifiers and INFO 1876 String parameters are the same as for the ASP Active message (See 1877 Section 3.3.2.3.). 1879 3.3.3.3 TEI Status Messages (Request, Confirm and Indication) 1881 The TEI Status messages are exchanged between IUA layer peers to 1882 request, confirm and indicate the status of a particular TEI. 1884 The TEI Status messages contain the common message header followed by 1885 IUA message header. The TEI Status Request message does not contain 1886 any additional parameters. 1888 In the integrated ISDN Layer 2/3 model (e.g., in traditional ISDN 1889 switches), it is assumed that the Layer Management for the Q.921 1890 Layer and the Q.931 layer are co-located. When backhauling ISDN, 1891 this assumption is not necessarily valid. The TEI status messages 1892 allow the two Layer Management entities to communicate the status of 1893 the TEI. In addition, knowing that a TEI is in service allows the 1894 ASP to request the SG to establish the datalink to the terminal (via 1895 the IUA Establish message) for signaling if the ASP wants to be in 1896 control of data link establishment. Another use of the TEI status 1897 procedure is where the Layer Management at the ASP can prepare for 1898 send/receive signaling to/from a given TEI and confirm/verify the 1899 establishment of a datalink to that TEI. For example, if a datalink 1900 is established for a TEI that the ASP did not know was assigned, the 1901 ASP can check to see whether it was assigned or whether there was an 1902 error in the signaling message. Also, knowing that a TEI is out of 1903 service, the ASP need not request the SG to establish a datalink to 1904 that TEI. 1906 The TEI Status Indication, and Confirm messages contain the following 1907 parameter: 1909 STATUS 1911 0 1 2 3 1912 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 1913 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1914 | Tag = 0x0010 | Length = 8 | 1915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1916 | Status | 1917 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1919 The valid values for Status are shown in the following table. 1921 Define Value Description 1922 ASSIGNED 0x0 TEI is considered assigned by Q.921 1923 UNASSIGNED 0x1 TEI is considered unassigned by Q.921 1925 3.3.3.4 TEI Query Message (Request) 1927 The TEI Query message is sent by the ASP to query the TEI(s). 1928 This message consists of the common header and IUA header. 1929 The DLCI in the IUA header MUST be ignored by the SG. The 1930 SG will respond to this message with TEI Status Indication(s). 1932 4.0 Procedures 1934 The IUA layer needs to respond to various primitives it receives from 1935 other layers as well as messages it receives from the peer IUA layer. 1936 This section describes various procedures involved in response to 1937 these events. 1939 4.1 Procedures to support service in section 1.4.1 1941 These procedures achieve the IUA layer's "Transport of Q.921/Q.931 1942 boundary" service. 1944 4.1.1 Q.921 or Q.931 primitives procedures 1946 On receiving these primitives from the local layer, the IUA layer 1947 will send the corresponding QPTM message (Data, Unit Data, Establish, 1948 Release) to its peer. While doing so, the IUA layer needs to fill 1949 various fields of the common and specific headers correctly. In 1950 addition the message needs to be sent on the SCTP stream that 1951 corresponds to the D channel (Interface Identifier). 1953 4.1.2 QPTM message procedures 1955 On receiving QPTM messages from a peer IUA layer, the IUA layer on an 1956 SG or MGC needs to invoke the corresponding layer primitives (DL- 1957 ESTABLISH, DL-DATA, DL-UNIT DATA, DL-RELEASE) to the local Q.921 or 1958 Q.931 layer. 1960 4.2 Procedures to support service in section 1.4.2 1962 These procedures achieve the IUA layer's "Support for Communication 1963 between Layer Managements" service. 1965 4.2.1 Layer Management primitives procedures 1967 On receiving these primitives from the local Layer Management, the 1968 IUA layer will provide the appropriate response primitive across the 1969 internal local Layer Management interface. 1971 An M-SCTP ESTABLISH request from Layer Management will initiate the 1972 establishment of an SCTP association. An M-SCTP ESTABLISH confirm 1973 will be sent to Layer Management when the initiated association set- 1974 up is complete. An M-SCTP ESTABLISH indication is sent to Layer 1975 Management upon successful completion of an incoming SCTP association 1976 set-up from a peer IUA node 1978 An M-SCTP RELEASE request from Layer Management will initiate the 1979 tear-down of an SCTP association. An M-SCTP RELEASE confirm will be 1980 sent by Layer Management when the association teardown is complete. 1981 An M-SCTP RELEASE indication is sent to Layer Management upon 1982 successful tear-down of an SCTP association initiated by a peer IUA. 1984 M-SCTP STATUS request and indication support a Layer Management query 1985 of the local status of a particular SCTP association. 1987 M-NOTIFY indication and M-ERROR indication indicate to Layer 1988 Management the notification or error information contained in a 1989 received IUA Notify or Error message respectively. These indications 1990 can also be generated based on local IUA events. 1992 M-ASP STATUS request/indication and M-AS-STATUS request/indication 1993 support a Layer Management query of the local status of a particular 1994 ASP or AS. No IUA peer protocol is invoked. 1996 M-ASP-UP request, M-ASP-DOWN request, M-ASP-INACTIVE request and M- 1997 ASP-ACTIVE request allow Layer Management at an ASP to initiate state 1998 changes. These requests result in outgoing IUA ASP UP, ASP DOWN, ASP 1999 INACTIVE and ASP ACTIVE messages. 2001 M-ASP-UP confirmation, M-ASP-DOWN confirmation, M-ASP-INACTIVE 2002 confirmation and M-ASP-ACTIVE confirmation indicate to Layer 2003 Management that the previous request has been confirmed. 2005 Upon receipt of a M-TEI Status primitive from Layer Management, the 2006 IUA will send the corresponding MGMT message (TEI Status) to its 2007 peer. While doing so, the IUA layer needs to fill various fields of 2008 the common and specific headers correctly. 2010 All MGMT messages are sent on a sequenced stream to ensure ordering. 2011 SCTP stream '0' SHOULD be used. 2013 4.2.2 Receipt of IUA Peer Management messages 2015 Upon receipt of IUA Management messages, the IUA layer MUST invoke 2016 the corresponding Layer Management primitive indications (e.g., M-AS 2017 Status ind., M-ASP Status ind., M-ERROR ind., M-TEI STATUS...) to the 2018 local layer management. 2020 M-NOTIFY indication and M-ERROR indication indicate to Layer 2021 Management the notification or error information contained in a 2022 received IUA Notify or Error message. These indications can also be 2023 generated based on local IUA events. 2025 All MGMT messages are sent on a sequenced stream to ensure ordering. 2026 SCTP stream '0' SHOULD be used. 2028 4.3 Procedures to support service in section 1.4.3 2030 These procedures achieve the IUA layer's "Support for management of 2031 active associations between SG and MGC" service. 2033 4.3.1 AS and ASP State Maintenance 2035 The IUA layer on the SG needs to maintain the states of each ASP as 2036 well as the state of the AS. 2038 4.3.1.1 ASP States 2040 The state of the each ASP, in each AS that it is configured, is 2041 maintained in the IUA layer on the SG. The state of an ASP changes 2042 due to the following type of events: 2044 * Reception of messages from peer IUA layer at that ASP 2045 * Reception of some messages from the peer IUA layer at other 2046 ASPs in the AS 2047 * Reception of indications from SCTP layer 2048 * Local Management intervention. 2050 The ASP state transition diagram is shown in Figure 6. The possible 2051 states of an ASP are the following: 2053 ASP-DOWN: Application Server Process is unavailable and/or the 2054 related SCTP association is down. Initially, all ASPs will be in 2055 this state. An ASP in this state SHOULD NOT be sent any IUA messages. 2057 ASP-INACTIVE: The remote IUA peer at the ASP is available (and the 2058 related SCTP association is up) but application traffic is stopped. 2059 In this state the ASP can be sent any non-QPTM IUA messages (except 2060 for TEI Status messages). 2062 ASP-ACTIVE: The remote IUA peer at the ASP is available and 2063 application traffic is active. 2065 Figure 6 ASP State Transition Diagram 2067 +--------------+ 2068 +----------------------| | 2069 | Alternate +-------| ASP-ACTIVE | 2070 | ASP | +--------------+ 2071 | Takeover | ^ | 2072 | | ASP | | ASP Inactive / 2073 | | Active | | ASP Up 2074 | | | v 2075 | | +--------------+ 2076 | | | | 2077 | +------>| ASP-INACTIVE | 2078 | +--------------+ 2079 | ^ | 2080 ASP Down/ | ASP | | ASP Down / 2081 SCTP CDI/ | Up | | SCTP CDI / 2082 SCTP RI | | v SCTP RI 2083 | +--------------+ 2084 +--------------------->| | 2085 | ASP-DOWN | 2086 +--------------+ 2088 SCTP CDI: The local SCTP layer's Communication Down Indication to 2089 the Upper Layer Protocol (IUA) on an SG. The local SCTP will send 2090 this indication when it detects the loss of connectivity to the ASP's 2091 peer SCTP layer. SCTP CDI is understood as either a SHUTDOWN 2092 COMPLETE notification and COMMUNICATION LOST notification from the 2093 SCTP. 2095 SCTP RI: The local SCTP layer's Restart indication to the upper 2096 layer protocol (IUA) on an SG. The local SCTP will send this 2097 indication when it detects a restart from the ASP's peer SCTP layer. 2099 4.3.1.2 AS States 2101 The state of the AS is maintained in the IUA layer on the SG. 2103 The state of an AS changes due to events. These events include the 2104 following: 2106 * ASP state transitions 2107 * Recovery timer triggers 2109 The possible states of an AS are the following: 2111 AS-DOWN: The Application Server is unavailable. This state implies 2112 that all related ASPs are in the ASP-DOWN state for this AS. 2113 Initially the AS will be in this state. 2115 AS-INACTIVE: The Application Server is available but no application 2116 traffic is active (i.e., one or more related ASPs are in the ASP- 2117 INACTIVE state, but none in the ASP-ACTIVE state). The recovery 2118 timer T(r) is not running or has expired. 2120 AS-ACTIVE: The Application Server is available and application 2121 traffic is active. This state implies that at least one ASP is in 2122 the ASP-ACTIVE state. 2124 AS-PENDING: An active ASP has transitioned from active to inactive or 2125 down and it was the last remaining active ASP in the AS. A recovery 2126 timer T(r) will be started and all incoming SCN messages will be 2127 queued by the SG. If an ASP becomes active before T(r) expires, the 2128 AS will move to AS-ACTIVE state and all the queued messages will be 2129 sent to the active ASP. 2131 If T(r) expires before an ASP becomes active, the SG stops queuing 2132 messages and discards all previously queued messages. The AS will 2133 move to AS-INACTIVE if at least one ASP is in ASP-INACTIVE state, 2134 otherwise it will move to AS-DOWN state. 2136 Figure 7: AS State Transition Diagram 2138 +----------+ one ASP trans to ASP-ACTIVE +-------------+ 2139 | AS- |---------------------------->| AS- | 2140 | INACTIVE | | ACTIVE | 2141 | |<--- | | 2142 +----------+ \ +-------------+ 2143 ^ | \ Tr Expiry, ^ | 2144 | | \ at least one | | 2145 | | \ ASP in ASP-INACTIVE | | 2146 | | \ | | 2147 | | \ | | 2148 | | \ | | 2149 one ASP | | all ASP \ one ASP | | Last ACTIVE 2150 trans | | trans to \ trans to | | ASP trans to 2151 to | | ASP-DOWN -------\ ASP- | | ASP-INACTIVE 2152 ASP- | | \ ACTIVE | | or ASP-DOWN 2153 INACTIVE| | \ | | (start Tr) 2154 | | \ | | 2155 | | \ | | 2156 | v \ | v 2157 +----------+ \ +-------------+ 2158 | | --| | 2159 | AS-DOWN | | AS-PENDING | 2160 | | | (queueing) | 2161 | |<----------------------------| | 2162 +----------+ Tr Expiry and no ASP +-------------+ 2163 in ASP-INACTIVE state) 2165 Tr = Recovery Timer 2167 4.3.2 ASPM procedures for primitives 2169 Before the establishment of an SCTP association the ASP state at both 2170 the SG and ASP is assumed to be in the state ASP-DOWN. 2172 As the ASP is responsible for initiating the setup of an SCTP 2173 association to an SG, the IUA layer at an ASP receives an M-SCTP 2174 ESTABLISH request primitive from the Layer Management, the IUA layer 2175 will try to establish an SCTP association with the remote IUA peer at 2176 an SG. Upon reception of an eventual SCTP-Communication Up confirm 2177 primitive from the SCTP, the IUA layer will invoke the primitive M- 2178 SCTP ESTABLISH confirm to the Layer Management. 2180 At the SG, the IUA layer will receive an SCTP Communication Up 2181 indication primitive from the SCTP. The IUA layer will then invoke 2182 the primitive M-SCTP ESTABLISH indication to the Layer Management. 2184 Once the SCTP association is established and assuming that the local 2185 IUA-User is ready, the local ASP IUA Application Server Process 2186 Maintenance (ASPM) function will initiate the ASPM procedures, using 2187 the ASP Up/-Down/-Active/-Inactive messages to convey the ASP state 2188 to the SG (see Section 4.3.3). 2190 The Layer Management and the IUA layer on SG can communicate the 2191 status of the application server using the M-AS_STATUS primitives. 2192 The Layer Management and the IUA layer on both the SG and ASP can 2193 communicate the status of an SCTP association using the M-SCTP_STATUS 2194 primitives. 2196 If the Layer Management on SG or ASP wants to bring down an SCTP 2197 association for management reasons, they would send M-SCTP RELEASE 2198 request primitive to the local IUA layer. The IUA layer would 2199 release the SCTP association and upon receiving the 2200 SCTP-COMMUNICATION_DOWN indication from the underlying SCTP layer, 2201 it would inform the local Layer Management using M-SCTP_RELEASE 2202 confirm primitive. 2204 If the IUA layer receives an SCTP-COMMUNICATION_DOWN indication from 2205 the underlying SCTP layer, it will inform the Layer Management by 2206 invoking the M-SCTP RELEASE indication primitive. The state of the 2207 ASP will be moved to "Down" at both the SG and ASP. 2209 At an ASP, the Layer Management MAY try to reestablish the SCTP 2210 association using M-SCTP_ESTABLISH request primitive. 2212 In the case of an SCTP-RESTART indication at an ASP, the ASP is now 2213 considered by its IUA peer to be in the ASP-DOWN state. The ASP, if 2214 it is to recover, must begin any recovery with the ASP Up procedure. 2216 4.3.3 ASPM procedures for peer-to-peer messages 2218 All ASPM messages are sent on a sequenced stream to ensure ordering. 2219 SCTP stream '0' SHOULD be used. 2221 4.3.3.1 ASP Up Procedures 2223 After an ASP has successfully established an SCTP association to an 2224 SG, the SG waits for the ASP to send an ASP Up message, indicating 2225 that the ASP IUA peer is available. The ASP is always the initiator 2226 of the ASP Up message. This action MAY be initiated at the ASP by 2227 an M-ASP_UP request primitive from Layer Management or MAY be 2228 initiated automatically by an IUA management function. 2230 When an ASP Up message is received at an SG and internally the 2231 remote ASP is in the ASP-DOWN state and not considered locked out 2232 for local management reasons, the SG marks the remote ASP in the 2233 state ASP-INACTIVE and informs Layer Management with an M-ASP_Up 2234 indication primitive. If the SG is aware, via current configuration 2235 data, which Application Servers the ASP is configured to operate in, 2236 the SG updates the ASP state to ASP-INACTIVE in each AS that it is 2237 a member. 2239 Alternatively, the SG may move the ASP into a pool of Inactive 2240 ASPs available for future configuration within Application Server(s), 2241 determined in a subsequent ASP Active procedure. If the ASP Up 2242 message contains an ASP Identifier, the SG should save the ASP 2243 Identifier for that ASP. The SG MUST send an ASP Up Ack message in 2244 response to a received ASP Up message even if the ASP is already 2245 marked as ASP-INACTIVE at the SG. 2247 If for any local reason (e.g., management lockout) the SG cannot 2248 respond with an ASP Up Ack message, the SG responds to an ASP Up 2249 message with an Error message with reason "Refused - Management 2250 Blocking". 2252 At the ASP, the ASP Up Ack message received is not acknowledged. 2253 Layer Management is informed with an M-ASP_UP confirm primitive. 2255 When the ASP sends an ASP Up message it starts timer T(ack). If 2256 the ASP does not receive a response to an ASP Up message within 2257 T(ack), the ASP MAY restart T(ack) and resend ASP Up messages until 2258 it receives an ASP Up Ack message. T(ack) is provisionable, with a 2259 default of 2 seconds. Alternatively, retransmission of ASP Up 2260 messages MAY be put under control of Layer Management. In this 2261 method, expiry of T(ack) results in an M-ASP_UP confirm primitive 2262 carrying a negative indication. 2264 The ASP must wait for the ASP Up Ack message before sending any 2265 other IUA messages (e.g., ASP Active). If the SG receives any other 2266 IUA messages before an ASP Up message is received (other than ASP 2267 Down - see Section 4.3.3.2), the SG MAY discard them. 2269 If an ASP Up message is received and internally the remote ASP is 2270 in the ASP-ACTIVE state, an ASP Up Ack message is returned, as well 2271 as an Error message ("Unexpected Message), and the remote ASP state 2272 is changed to ASP-INACTIVE in all relevant Application Servers. 2274 If an ASP Up message is received and internally the remote ASP is 2275 already in the ASP-INACTIVE state, an ASP Up Ack message is returned 2276 and no further action is taken. 2278 4.3.3.2 ASP Down Procedures 2280 The ASP will send an ASP Down message to an SG when the ASP wishes 2281 to be removed from the list of ASPs in all Application Servers that 2282 it is a member and no longer receive any IUA QPTM or ASPTM 2283 messages. This action MAY be initiated at the ASP by an M-ASP_DOWN 2284 request primitive from Layer Management or MAY be initiated 2285 automatically by an IUA management function. 2287 Whether the ASP is permanently removed from an AS is a function of 2288 configuration management. 2290 The SG marks the ASP as ASP-DOWN, informs Layer Management with 2291 an M-ASP_Down indication primitive, and returns an ASP Down Ack 2292 message to the ASP. 2294 The SG MUST send an ASP Down Ack message in response to a received 2295 ASP Down message from the ASP even if the ASP is already marked as 2296 ASP-DOWN at the SG. 2298 At the ASP, the ASP Down Ack message received is not acknowledged. 2299 Layer Management is informed with an M-ASP_DOWN confirm primitive. 2300 If the ASP receives an ASP Down Ack without having sent an ASP Down 2301 message, the ASP should now consider itself as in the ASP-DOWN state. 2302 If the ASP was previously in the ASP-ACTIVE or ASP-INACTIVE state, 2303 the ASP should then initiate procedures to return itself to its 2304 previous state. 2306 When the ASP sends an ASP Down message it starts timer T(ack). If 2307 the ASP does not receive a response to an ASP Down message within 2308 T(ack), the ASP MAY restart T(ack) and resend ASP Down messages until 2309 it receives an ASP Down Ack message. T(ack) is provisionable, with 2310 a default of 2 seconds. Alternatively, retransmission of ASP Down 2311 messages MAY be put under control of Layer Management. In this 2312 method, expiry of T(ack) results in an M-ASP_DOWN confirm primitive 2313 carrying a negative indication. 2315 4.3.3.3 IUA Version Control 2317 If a ASP Up message with an unsupported version is received, the 2318 receiving end responds with an Error message, indicating the version 2319 the receiving node supports and notifies Layer Management. 2321 This is useful when protocol version upgrades are being performed in 2322 a network. A node upgraded to a newer version SHOULD support the 2323 older versions used on other nodes it is communicating with. Because 2324 ASPs initiate the ASP Up procedure it is assumed that the Error 2325 message would normally come from the SG. 2327 4.3.3.4 ASP Active Procedures 2329 Any time after the ASP has received a ASP Up Ack from the SG, the 2330 ASP sends an ASP Active message to the SG indicating that the ASP 2331 is ready to start processing traffic. This action MAY be initiated 2332 at the ASP by an M-ASP_ACTIVE request primitive from Layer Management 2333 or MAY be initiated automatically by an IUA management function. 2334 In the case where an ASP is configured/registered to process the 2335 traffic for more than one Application Server across an SCTP 2336 association, the ASPAC contains one or more Interface Identifiers 2337 to indicate for which Application Servers the ASPAC applies. 2339 If the Application Server can be successfully activated, the SG 2340 responds responds to the ASP with a ASPAC Ack message acknowledging 2341 that the ASPAC message was received and starts sending traffic for 2342 the Application Server to that ASP. 2344 In the case where an "out-of-the-blue" ASP Active message is 2345 received (i.e., the ASP has not registered with the SG or the 2346 SG has no static configuration data for the ASP), the message 2347 MAY be silently discarded. 2349 The SG MUST send an ASP Active Ack message in response to a 2350 received ASP Active message from the ASP, if the ASP is already 2351 marked in the ASP-ACTIVE state at the SG. 2353 At the ASP, the ASP Active Ack message received is not 2354 acknowledged. Layer Management is informed with an M-ASP_ACTIVE 2355 confirm primitive. It is possible for the ASP to receive Data 2356 message(s) before the ASP Active Ack message as the ASP Active Ack 2357 and Data messages from an SG may be sent on different SCTP streams. 2358 Message loss is possible as the ASP does not consider itself in the 2359 ASP-ACTIVE state until reception of the ASP Active Ack message. 2361 When the ASP sends an ASP Active message it starts timer T(ack). 2362 If the ASP does not receive a response to an ASP Active message 2363 within T(ack), the ASP MAY restart T(ack) and resend ASP Active 2364 messages until it receives an ASP Active Ack message. T(ack) is 2365 provisionable, with a default of 2 seconds. Alternatively, 2366 retransmission of ASP Active messages MAY be put under control of 2367 Layer Management. In this method, expiry of T(ack) results in an 2368 M-ASP_ACTIVE confirm primitive carrying a negative indication. 2370 The ASP MUST wait for the ASP-Active Ack message from the SG before 2371 sending any Data messages or it will risk message loss. If the SG 2372 receives QPTM messages before an ASP Active is received, the SG 2373 SHOULD discard these messages. 2375 There are two modes of Application Server traffic handling in the SG 2376 IUA - Over-ride and Load-sharing. The Type parameter in the ASPAC 2377 message indicates the mode used in a particular Application Server. 2378 If the SG determines that the mode indicates in an ASPAC is 2379 incompatible with the traffic handling mode currently used in the AS, 2380 the SG responds with an Error message indicating Unsupported Traffic 2381 Handling Mode. 2383 In the case of an Over-ride mode AS, reception of an ASPAC message at 2384 an SG causes the redirection of all traffic for the AS to the ASP 2385 that sent the ASPAC. The SG responds to the ASPAC with an ASP-Active 2386 Ack message to the ASP. Any previously active ASP in the AS is now 2387 considered Inactive and will no longer receive traffic from the SG 2388 within the AS. The SG sends a Notify (Alternate ASP-Active) to the 2389 previously active ASP in the AS, after stopping all traffic to that 2390 ASP. 2392 In the case of a load-share mode AS, reception of an ASPAC message at 2393 an SG causes the direction of traffic to the ASP sending the ASPAC, 2394 in addition to all the other ASPs that are currently active in the 2395 AS. The algorithm at the SG for load-sharing traffic within an AS to 2396 all the active ASPs is implementation dependent. The algorithm 2397 could, for example be round-robin or based on information in the Data 2398 message, such as Interface Identifier, depending on the requirements 2399 of the application and the call state handling assumptions of the 2400 collection of ASPs in the AS. The SG responds to the ASPAC with a 2401 ASP Active Ack message to the ASP. 2403 4.3.3.5 ASP Inactive Procedures 2405 When an ASP wishes to withdraw from receiving traffic within an AS, 2406 the ASP sends an ASP Inactive message to the SG. This action MAY be 2407 initiated at the ASP by an M-ASP_INACTIVE request primitive from 2408 Layer Management or MAY be initiated automatically by an IUA 2409 management function. In the case where an ASP is configured/- 2410 registered to process the traffic for more than one Application 2411 Server across an SCTP association, the ASPIA contains one or more 2412 Interface Identifiers to indicate for which Application Servers the 2413 ASP Inactive message applies. 2415 There are two modes of Application Server traffic handling in the SG 2416 IUA when withdrawing an ASP from service: Over-ride and Load- 2417 sharing. In the case of an Over-ride mode AS, where normally another 2418 ASP has already taken over the traffic within the AS with an 2419 Over-ride ASPAC message, the ASP which sends the ASPIA message is 2420 already considered by the SG to be ASP-INACTIVE. An ASPIA Ack 2421 message is sent to the ASP, after ensuring that all traffic is 2422 stopped to the ASP. 2424 In the case of a Load-share mode AS, the SG moves the ASP to the 2425 ASP-INACTIVE state and the AS traffic is re-allocated across the 2426 remaining ASP-ACTIVE ASPs per the load-sharing algorithm currently 2427 used within the AS. An ASPIA Ack message is sent to the ASP after 2428 all traffic is halted to the ASP. A NOTIFY (Insufficient ASPs) 2429 message MAY be sent to all inactive ASPs, if required. 2431 When the ASP sends an ASP Inactive message it starts timer T(ack). 2432 If the ASP does not receive a response to an ASP Inactive message 2433 within T(ack), the ASP MAY restart T(ack) and resend ASP Inactive 2434 messages until it receives an ASP Inactive Ack message. T(ack) 2435 is provisionable, with a default of 2 seconds. Alternatively, 2436 retransmission of ASP Inactive messages MAY be put under control of 2437 Layer Management. In this method, expiry of T(ack) results in a 2438 M-ASP_Inactive confirm primitive carrying a negative indication. 2440 If no other ASPs in the Application Server are in the state 2441 ASP-ACTIVE, the SG MUST send a Notify ("AS-Pending") message to 2442 all of the ASPs in the AS which are in the state ASP-INACTIVE. 2443 The SG SHOULD start buffering the incoming messages for T(r) 2444 seconds, after which messages MAY be discarded. T(r) is 2445 configurable by the network operator. If the SG receives an ASP 2446 Active message from an ASP in the AS before expiry of T(r), the 2447 buffered traffic is directed to that ASP and the timer is cancelled. 2448 If T(r) expires, the AS is moved to the AS-INACTIVE state. 2450 At the ASP, the ASP Inactive Ack message received is not 2451 acknowledged. Layer Management is informed with an M-ASP_INACTIVE 2452 confirm primitive. If the ASP receives an ASP Inactive Ack without 2453 having sent an ASP Inactive message, the ASP should now consider 2454 itself as in the ASP-INACTIVE state. If the ASP was previously in 2455 the ASP-ACTIVE state, the ASP should then initiate procedures to 2456 return itself to its previous state. 2458 4.3.3.6 Notify Procedures 2460 A Notify message reflecting a change in the AS state MUST be sent 2461 to all ASPs in the AS, except those in the ASP-DOWN state, with 2462 appropriate Status Information and any ASP Identifier of the 2463 failed ASP. At the ASP, Layer Management is informed with an 2464 M-NOTIFY indication primitive. The Notify message must be sent 2465 whether the AS state change was a result of an ASP failure or 2466 reception of an ASP State management (ASPSM) / ASP Traffic Management 2467 (ASPTM) message. In the second case, the Notify message MUST be 2468 sent after any related acknowledgement messages (e.g., ASP Up Ack, 2469 ASP Down Ack, ASP Active Ack, or ASP Inactive Ack). 2471 In the case where a Notify ("AS-Pending") message is sent by an SG 2472 that now has no ASPs active to service the traffic, or a NTFY 2473 ("Insufficient ASPs") is sent in the Load-share mode, the Notify does 2474 not explicitly compel the ASP(s) receiving the message to become 2475 active. The ASPs remain in control of what (and when) action is 2476 taken. 2478 4.3.3.7 Heartbeat 2480 The optional Heartbeat procedures MAY be used when operating over 2481 transport layers that do not have their own heartbeat mechanism for 2482 detecting loss of the transport association (i.e., other than the 2483 SCTP). 2485 Either IUA peer may optionally send Heartbeat messages periodically, 2486 subject to a provisionable timer T(beat). Upon receiving a Heartbeat 2487 message, the IUA peer MUST respond with a Heartbeat Ack message. 2489 If no Heartbeat Ack message (or any other IUA message) is received 2490 from the IUA peer within 2*T(beat), the remote IUA peer is 2491 considered unavailable. Transmission of Heartbeat messages is 2492 stopped and the signalling process SHOULD attempt to re-establish 2493 communication if it is configured as the client for the 2494 disconnected IUA peer. 2496 The BEAT message MAY optionally contain an opaque Heartbeat Data 2497 parameter that MUST be echoed back unchanged in the related Beat Ack 2498 message. The ASP upon examining the contents of the returned BEAT 2499 Ack message MAY choose to consider the remote ASP as unavailable. 2500 The contents/format of the Heartbeat Data parameter is 2501 implementation-dependent and only of local interest to the original 2502 sender. The contents MAY be used, for example, to support a 2503 Heartbeat sequence algorithm (to detect missing Heartbeats), and/or a 2504 timestamp mechanism (to evaluate delays). 2506 Note: Heartbeat related events are not shown in Figure 6 "ASP state 2507 transition diagram". 2509 5.0 Examples 2511 5.1 Establishment of Association and Traffic between SGs and ASPs 2513 5.1.1 Single ASP in an Application Server (1+0 sparing) 2515 This scenario shows the example IUA message flows for the 2516 establishment of traffic between an SG and an ASP, where only one ASP 2517 is configured within an AS (no backup). It is assumed that the SCTP 2518 association is already set-up. 2520 SG ASP1 2521 | 2522 |<---------ASP Up----------| 2523 |--------ASP Up Ack------->| 2524 | | 2525 |-----NTFY(AS-INACTIVE)--->| 2526 | | 2527 |<-------ASP Active--------| 2528 |------ASP Active Ack----->| 2529 | | 2530 |------NTFY(AS-ACTIVE)---->| 2531 | | 2533 5.1.2 Two ASPs in Application Server (1+1 sparing) 2535 This scenario shows the example IUA message flows for the 2536 establishment of traffic between an SG and two ASPs in the same 2537 Application Server, where ASP1 is configured to be Active and ASP2 a 2538 standby in the event of communication failure or the withdrawal from 2539 service of ASP1. ASP2 MAY act as a hot, warm, or cold standby 2540 depending on the extent to which ASP1 and ASP2 share call state or 2541 can communicate call state under failure/withdrawal events. The 2542 example message flow is the same whether the ASP-Active messages are 2543 Over-ride or Load-share mode although typically this example would 2544 use an Over-ride mode. 2546 SG ASP1 ASP2 2547 | | | 2548 |<--------ASP Up----------| | 2549 |-------ASP Up Ack------->| | 2550 | | | 2551 |----NTFY(AS-INACTIVE)--->| | 2552 | | | 2553 |<-----------------------------ASP Up----------------| 2554 |----------------------------ASP Up Ack------------->| 2555 | | | 2556 | | | 2557 |<-------ASP Active-------| | 2558 |-----ASP Active Ack----->| | 2559 | | | 2560 |-----NTFY(AS-ACTIVE)---->| | 2561 |----------------------NTFY(AS-ACTIVE)-------------->| 2563 5.1.3 Two ASPs in an Application Server (1+1 sparing, load-sharing case) 2565 This scenario shows a similar case to Section 5.1.2 but where the two 2566 ASPs are brought to active and load-share the traffic load. In this 2567 case, one ASP is sufficient to handle the total traffic load. 2569 SG ASP1 ASP2 2570 | | | 2571 |<---------ASP Up---------| | 2572 |--------ASP Up Ack------>| | 2573 | | | 2574 |----NTFY(AS-INACTIVE)--->| | 2575 | | | 2576 |<------------------------------ASP Up---------------| 2577 |-----------------------------ASP Up Ack------------>| 2578 | | | 2579 | | | 2580 |<--ASP Active (Ldshr)----| | 2581 |----ASP Active Ack------>| | 2582 | | | 2583 |-----NTFY(AS-ACTIVE)---->| | 2584 |----------------------NTFY(AS-ACTIVE)-------------->| 2585 | | | 2586 |<----------------------------ASP Active (Ldshr)-----| 2587 |-----------------------------ASP Active Ack-------->| 2588 | | | 2590 5.1.4 Three ASPs in an Application Server (n+k sparing, load-sharing 2591 case) 2593 This scenario shows the example IUA message flows for the 2594 establishment of traffic between an SG and three ASPs in the same 2595 Application Server, where two of the ASPs are brought to active and 2596 share the load. In this case, a minimum of two ASPs are required to 2597 handle the total traffic load (2+1 sparing). 2599 SG ASP1 ASP2 ASP3 2600 | | | | 2601 |<------ASP Up-------| | | 2602 |-----ASP Up Ack---->| | | 2603 | | | | 2604 |-NTFY(AS-INACTIVE)->| | | 2605 | | | | 2606 |<--------------------------ASP Up-------| | 2607 |-----------------------ASP Up Ack------>| | 2608 | | | | 2609 |<---------------------------------------------ASP Up--------| 2610 |--------------------------------------------ASP Up Ack----->| 2611 | | | | 2612 | | | | 2613 |<-ASP Act (Ldshr)---| | | 2614 |----ASP Act Ack---->| | | 2615 | | | | 2616 |<---------------------ASP Act (Ldshr)---| | 2617 |----------------------ASP Act Ack------>| | 2618 | | | | 2619 |--NTFY(AS-ACTIVE)-->| | | 2620 |---------------NTFY(AS-ACTIVE)--------->| | 2621 |------------------------NTFY(AS-ACTIVE)-------------------->| 2623 5.1.5 Interface Identifier Configuration Mismatch Example 2625 This scenario shows the example IUA message flows for the 2626 establishment of traffic between an SG and an ASP in which some 2627 of the Interface Identifiers have been misconfigured on the 2628 ASP side. The SG in this case has Interface Identifers 1-5 2629 configured for ASP1. 2631 SG ASP1 2632 | | 2633 | | 2634 |<----ASP Active (IIDs 1-10)-----| 2635 |---ASP Active Ack (IIDs 1-5)--->| 2636 |-------Error (IIDs 6)---------->| 2637 |-------Error (IIDs 7)---------->| 2638 |-------Error (IIDs 8)---------->| 2639 |-------Error (IIDs 9)---------->| 2640 |-------Error (IIDs 10)--------->| 2641 | | 2643 5.2 ASP Traffic Fail-over Examples 2645 5.2.1 (1+1 Sparing, withdrawal of ASP, Back-up Over-ride) 2647 The following example shows a case in which an ASP withdraws from 2648 service: 2650 SG ASP1 ASP2 2651 | | | 2652 |<-----ASP Inactive-------| | 2653 |----ASP Inactive Ack---->| | 2654 | | | 2655 |----NTFY(AS-Pending)---->| | 2656 |-------------------NTFY(AS-Pending)---------------->| 2657 | | | 2658 |<------------------------------ ASP Active----------| 2659 |-----------------------------ASP Active Ack)------->| 2660 | | | 2661 |----NTFY(AS-ACTIVE)----->| | 2662 |-------------------NTFY(AS-ACTIVE)----------------->| 2664 In this case, the SG notifies ASP2 that the AS has moved to the Down 2665 state. The SG could have also (optionally) sent a Notify message 2666 when the AS moved to the Pending state. 2668 Note: If the SG detects loss of the IUA peer (IUA heartbeat loss or 2669 detection of SCTP failure), the initial SG-ASP1 ASP Inactive message 2670 exchange would not occur. 2672 5.2.2 (1+1 Sparing, Back-up Over-ride) 2674 The following example shows a case in which ASP2 wishes to over-ride 2675 ASP1 and take over the traffic: 2677 SG ASP1 ASP2 2678 | | | 2679 |<-------------------------------ASP Active----------| 2680 |-----------------------------ASP Active Ack-------->| 2681 |----NTFY( Alt ASP-Act)-->| 2682 | | | 2684 In this case, the SG notifies ASP1 that an alternative ASP has 2685 overridden it. 2687 5.2.3 (n+k Sparing, Load-sharing case, withdrawal of ASP) 2689 Following on from the example in Section 5.1.4, and ASP1 withdraws 2690 from service 2692 SG ASP1 ASP2 ASP3 2693 | | | | 2694 |<----ASP Inact------| | | 2695 |---ASP Inact Ack--->| | | 2696 | | | | 2697 |---------------------------------NTFY(Ins. ASPs)----------->| 2698 | | | | 2699 |<-----------------------------------------ASP Act (Ldshr)---| 2700 |-------------------------------------------ASP Act (Ack)--->| 2701 | | | | 2703 In this case, the SG has knowledge of the minimum ASP resources 2704 required (implementation dependent) for example if the SG knows that 2705 n+k = 2+1 for a load-share AS and n currently equals 1. 2707 Note: If the SG detects loss of the ASP1 IUA peer (IUA heartbeat 2708 loss or detection of SCTP failure), the first SG-ASP1 ASP Inactive 2709 message exchange would not occur. 2711 5.3 Q.921/Q.931 primitives backhaul Examples 2713 When the IUA layer on the ASP has a QPTM message to send to the SG, 2714 it will do the following: 2716 - Determine the correct SG 2718 - Find the SCTP association to the chosen SG 2720 - Determine the correct stream in the SCTP association based on 2721 the D channel 2723 - Fill in the QPTM message, fill in IUA Message Header, fill in 2724 Common Header 2726 - Send the QPTM message to the remote IUA peer in the SG, over 2727 the SCTP association 2729 When the IUA layer on the SG has a QPTM message to send to the ASP, 2730 it will do the following: 2732 - Determine the AS for the Interface Identifier 2734 - Determine the Active ASP (SCTP association) within the AS 2736 - Determine the correct stream in the SCTP association based on 2737 the D channel 2739 - Fill in the QPTM message, fill in IUA Message Header, fill in 2740 Common Header 2742 - Send the QPTM message to the remote IUA peer in the ASP, over 2743 the SCTP association 2745 An example of the message flows for establishing a data link on a 2746 signaling channel, passing PDUs and releasing a data link on a 2747 signaling channel is shown below. An active association between MGC 2748 and SG is established (Section 5.1) prior to the following message 2749 flows. 2751 SG ASP 2753 <----------- Establish Request 2754 Establish Confirm ----------> 2756 <----------- Data Request 2757 Data Indication -----------> 2758 <----------- Data Request 2759 Data Indication -----------> 2760 <----------- Data Request 2761 <----------- Data Request 2762 Data Indication -----------> 2764 <----------- Release Request (RELEASE_MGMT) 2765 Release Confirm ----------> 2767 An example of the message flows for a failed attempt to establish a 2768 data link on the signaling channel is shown below. In this case, the 2769 gateway has a problem with its physical connection (e.g., Red Alarm), 2770 so it cannot establish a data link on the signaling channel. 2772 SG ASP 2774 <----------- Establish Request (ESTABLISH_START) 2775 Release Indication ----------> 2776 (RELEASE_PHYS) 2778 5.4 Layer Management Communication Examples 2780 An example of the message flows for communication between Layer 2781 Management modules between SG and ASP is shown below. An active 2782 association between ASP and SG is established (Section 5.1) prior to 2783 the following message flows. 2785 SG ASP 2787 <----------- Data Request 2788 Error Indication ----------> 2789 (INVALID_TEI) 2791 <----------- TEI Status Request 2792 TEI Status Confirm ----------> 2793 (Unassigned) 2795 6.0 Security 2797 The security considerations discussed for the 'Security 2798 Considerations for SIGTRAN Protocols' RFC 3788 [3] document apply 2799 to this document. 2801 7.0 IANA Considerations 2803 7.1 SCTP Payload Protocol Identifier 2805 A request will be made to IANA to assign an IUA value for the Payload 2806 Protocol Identifier in SCTP Payload Data chunk. The following SCTP 2807 Payload Protocol Identifier will be registered: 2809 IUA "1" 2811 The SCTP Payload Protocol Identifier is included in each SCTP Data 2812 chunk, to indicate which protocol the SCTP is carrying. This Payload 2813 Protocol Identifier is not directly used by SCTP but MAY be used by 2814 certain network entities to identify the type of information being 2815 carried in a Data chunk. 2817 The User Adaptation peer MAY use the Payload Protocol Identifier as a 2818 way of determining additional information about the data being 2819 presented to it by SCTP. 2821 7.2 IUA Protocol Extensions 2823 This protocol may also be extended through IANA in three ways: 2825 -- through definition of additional message classes, 2826 -- through definition of additional message types, and 2827 -- through definition of additional message parameters. 2829 The definition and use of new message classes, types and parameters 2830 is an integral part of SIGTRAN adaptation layers. Thus, these 2831 extensions are assigned by IANA through an IETF Consensus action as 2832 defined in [9]. 2834 The proposed extension must in no way adversely affect the general 2835 working of the protocol. 2837 7.2.1 IETF Defined Message Classes 2839 The documentation for a new message class MUST include the following 2840 information: 2842 (a) A long and short name for the message class. 2843 (b) A detailed description of the purpose of the message class. 2845 7.2.2 IETF Defined Message Types 2847 Documentation of the message type MUST contain the following 2848 information: 2850 (a) A long and short name for the new message type. 2851 (b) A detailed description of the structure of the message. 2852 (c) A detailed definition and description of intended use of each 2853 field within the message. 2854 ti3 (d) A detailed procedural description of the use of the new 2855 message type within the operation of the protocol. 2856 (e) A detailed description of error conditions when receiving this 2857 message type. 2859 When an implementation receives a message type which it does not 2860 support, it MUST respond with an Error (ERR) message with an Error 2861 Code of Unsupported Message Type. 2863 7.2.3 IETF-defined TLV Parameter Extension 2865 Documentation of the message parameter MUST contain the following 2866 information: 2868 (a) Name of the parameter type. 2869 (b) Detailed description of the structure of the parameter field. 2870 This structure MUST conform to the general type-length-value 2871 format described in Section 3.1.5. 2872 (c) Detailed definition of each component of the parameter value. 2873 (d) Detailed description of the intended use of this parameter type, 2874 and an indication of whether and under what circumstances 2875 multiple instances of this parameter type may be found within the 2876 same message type. 2878 8.0 Timer Values 2880 The following are suggestions for default timer values. 2882 T(r) 3-5 seconds 2883 T(ack) 2-5 seconds 2884 T(beat) Heartbeat Timer 30 seconds 2886 9.0 Acknowledgements 2888 The authors would like to thank Alex Audu, Maria Sonia Vazquez 2889 Arevalillo, Ming-te Chao, Keith Drage, Norm Glaude, Nikhil Jain, 2890 Bernard Kuc, Ming Lin, Stephen Lorusso, John Loughney, Barry 2891 Nagelberg, Neil Olson, Lyndon Ong, Heinz Prantner, Jose Luis Jimenez 2892 Ramirez, Ian Rytina, Michael Tuexen and Hank Wang for their valuable 2893 comments and suggestions. 2895 10.0 References 2897 10.1 Normative 2899 [1] ITU-T Recommendation Q.920, 'Digital Subscriber signaling System 2900 No. 1 (DSS1) - ISDN User-Network Interface Data Link Layer - 2901 General Aspects' 2903 [2] Coded Character Set--7-Bit American Standard Code for 2904 Information Interchange, ANSI X3.4-1986. 2906 [3] J. Loughney, M. Tuexen, J. Pastor-Balbas, 'Security Considerations 2907 for SIGTRAN Protocols', RFC 3788, June 2004. 2909 10.2 Informative 2911 [4] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H., 2912 Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson, 2913 "Stream Control Transmission Protocol", RFC 2960, October 2000. 2915 [5] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene, L., 2916 Lin, H., Juhasz, I., Holdrege, M., and C. Sharp, "Architectural 2917 Framework for Signaling Transport", RFC 2719, October 1999. 2919 [6] Fraser, B., "Site Security Handbook", FYI 8, RFC 2196, September 2920 1997. 2922 [7] Kent, S. and R. Atkinson, "Security Architecture for the Internet 2923 Protocol", RFC 2401, November 1998. 2925 [8] Bradner, S., "Key words for use in RFCs to Indicate Requirement 2926 Levels", BCP 14, RFC 2119, March 1997. 2928 [9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA 2929 Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. 2931 [10] Stone, J., Stewart, R., Otis, D., "Stream Control Transmission 2932 Protocol (SCTP) Checksum Change", RFC 3309, September 2002 2934 11.0 Change Log 2936 Below is a list of the major changes between this document and 2937 RFC3057. 2939 1. The TEI Query message was added. 2941 2. An explanation of the DLCI format (shown in Figure 6) is 2942 provided. 2944 3. Aligned the ASP and AS procedures in Section 4 with RFC3331 and 2945 RFC3332. 2947 4. Alinged the format of the ASPSM and ASPTM messages with RFC3331 2948 and RFC3332. These changes include removing the Reason field 2949 from the ASP Down and ASP Down Ack messages and the Traffic Mode 2950 Type field from the ASP Inactive and ASP Inactive Ack messages. 2952 5. Sections 1.3.3 and 1.3.4 were moved to Appendix A. A new section 2953 was added in place of Section 1.3.3. 2955 6. The references have been split between Normative and Informative. 2957 7. The new Sigtran security draft is referenced and Section 6.0 has 2958 been updated appropriately. 2960 12.0 Authors' Addresses 2962 Ken Morneault 2963 Cisco Systems Inc. 2964 13615 Dulles Technology Drive 2965 Herndon, VA. 20171 2966 USA 2968 Phone: +1-703-484-3323 2969 EMail: kmorneau@cisco.com 2971 Malleswar Kalla 2972 Telcordia Technologies 2973 PYA 2J-341 2974 3 Corporate Place 2975 Piscataway, NJ 08854 2976 USA 2978 Phone: +1-732-699-3728 2979 EMail: mkalla@telcordia.com 2981 Selvam Rengasami 2982 Telcordia Technologies 2983 NVC-2Z439 2984 331 Newman Springs Road 2985 Red Bank, NJ 07701 2986 USA 2988 Phone: +1-732-758-5260 2989 EMail: srengasa@telcordia.com 2991 Greg Sidebottom 2992 Signatus Technologies 2993 Kanata, Ontario, Canada 2995 EMail: greg@signatustechnologies.com 2997 Appendix A 2999 A.1 Signaling Network Architecture 3001 A Signaling Gateway is used to support the transport of Q.921-User 3002 signaling traffic to one or more distributed ASPs (e.g., MGCs). 3003 Clearly, the IUA protocol is not designed to meet the performance and 3004 reliability requirements for such transport by itself. However, the 3005 conjunction of distributed architecture and redundant networks does 3006 allow for a sufficiently reliable transport of signaling traffic over 3007 IP. The IUA protocol is flexible enough to allow its operation and 3008 management in a variety of physical configurations, enabling Network 3009 Operators to meet their performance and reliability requirements. 3011 To meet the ISDN signaling reliability and performance requirements 3012 for carrier grade networks, Network Operators SHOULD ensure that 3013 there is no single point of failure provisioned in the end-to-end 3014 network architecture between an ISDN node and an IP ASP. 3016 Depending of course on the reliability of the SG and ASP functional 3017 elements, this can typically be met by the provision of redundant 3018 QOS-bounded IP network paths for SCTP Associations between SCTP End 3019 Points, and redundant Hosts, and redundant SGs. The distribution of 3020 ASPs within the available Hosts is also important. For a particular 3021 Application Server, the related ASPs SHOULD be distributed over at 3022 least two Hosts. 3024 An example logical network architecture relevant to carrier-grade 3025 operation in the IP network domain is shown in Figure 8 below: 3027 Host1 3028 ******** ************** 3029 * *_________________________________________* ******** * 3030 * * _________* * ASP1 * * 3031 * SG1 * SCTP Associations | * ******** * 3032 * *_______________________ | * * 3033 ******** | | ************** 3034 | | 3035 ******** | | 3036 * *_______________________________| 3037 * * | 3038 * SG2 * SCTP Associations | 3039 * *____________ | 3040 * * | | Host2 3041 ******** | | ************** 3042 | |_________________* ******** * 3043 |____________________________* * ASP1 * * 3044 * ******** * 3045 * * 3046 ************** 3047 . 3048 . 3049 . 3051 Figure 8 - Logical Model Example 3053 For carrier grade networks, the failure or isolation of a particular 3054 ASP SHOULD NOT cause stable calls to be dropped. This implies that 3055 ASPs need, in some cases, to share the call state or be able to pass 3056 the call state between each other. However, this sharing or 3057 communication of call state information is outside the scope of this 3058 document. 3060 A.2 Application Server Process Redundancy 3062 To avoid a single point of failure, it is recommended that a minimum 3063 of two ASPs be in the list, resident in separate hosts and therefore 3064 available over different SCTP Associations. For example, in the 3065 network shown in Figure 8, all messages from a particular D Channel 3066 (Interface Identifier) could be sent to ASP1 in Host1 or ASP1 in 3067 Host2. The AS list at SG1 might look like the following: 3069 Interface Identifier(s) - Application Server #1 3070 ASP1/Host1 - State=Up, Active 3071 ASP1/Host2 - State=Up, Inactive 3073 In this 1+1 redundancy case, ASP1 in Host1 would be sent any incoming 3074 message for the Interface Identifiers registered. ASP1 in Host2 3075 would normally be brought to the active state upon failure of, or 3076 loss of connectivity to, ASP1/Host1. In this example, both ASPs are 3077 Up, meaning that the related SCTP association and far-end IUA peer is 3078 ready. 3080 The AS List at SG1 might also be set up in load-share mode as shown 3081 below: 3083 Interface Identifier(s) - Application Server #1 3084 ASP1/Host1 - State=Up, Active 3085 ASP1/Host2 - State=Up, Active 3087 In this case, both the ASPs would be sent a portion of the traffic. 3089 In the process of fail-over, it is recommended that in the case of 3090 ASPs supporting call processing, stable calls do not get released. 3091 It is possible that calls in transition MAY fail, although measures 3092 of communication between the ASPs involved can be used to mitigate 3093 this problem. For example, the two ASPs MAY share call state via 3094 shared memory, or MAY use an ASP to ASP protocol to pass call state 3095 information. The ASP to ASP protocol is outside the scope of this 3096 document. 3098 Intellectual Property Statement 3100 The IETF takes no position regarding the validity or scope of any 3101 Intellectual Property Rights or other rights that might be claimed to 3102 pertain to the implementation or use of the technology described in 3103 this document or the extent to which any license under such rights 3104 might or might not be available; nor does it represent that it has 3105 made any independent effort to identify any such rights. 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Please address the information to the IETF at 3120 ietf-ipr@ietf.org. 3122 Disclaimer of Validity 3124 This document and the information contained herein are provided on an 3125 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 3126 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 3127 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 3128 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 3129 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 3130 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 3132 Copyright Statement 3134 Copyright (C) The Internet Society (2005). This document is subject 3135 to the rights, licenses and restrictions contained in BCP 78, and 3136 except as set forth therein, the authors retain all their rights. 3138 Acknowledgment 3140 Funding for the RFC Editor function is currently provided by the 3141 Internet Society.