1、INTERNATIONAL TELECOMMUNICATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Q.2150.2 (05/2001) SERIES Q: SWITCHING AND SIGNALLING Broadband ISDN - Signalling ATM adaptation layer (SAAL) Signalling Transport Converter on SSCOP and SSCOPMCE ITU-T Recommendation Q.2150.2 (Formerly CCIl
2、T Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 SPECIFICATIONS OF SIGNALLIN
3、G SYSTEM R1 SPECIFICATIONS OF SIGNALLING SYSTEM R2 DIGITAL EXCHANGES INTERWORKING OF SIGNALLING SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 43 INTERFACE DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 PUBLIC LAND MOBILE NETWORK INTERWORKING WITH SATELLITE MOBILE SYSTEMS INTELLIGENT NETWORK INTERNAT
4、IONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 SPECIFICATIONS OF SIGNALLING RELATED TO BEARER INDEPENDENT CALL CONTROL (BICC) 4.14.3 4.4-4.59 Q.6O-Q.99 Q. lOO-Q.119 Q. 120-Q.249 4.250-4.309 Q.31O-Q.399 Q.40O-
5、Q.499 Q.50O-Q.599 Q.60O-Q.699 4.700-4.799 Q.80O-Q.849 Q.SSO-Q.999 Q. 100O-Q. 1099 Q. 1 l0o-Q. 1 199 Q.120O-Q.1699 Q. 17004.1799 Q. 1900-Q. 1999 BROADBAND ISDN Q.200O-Q.2999 General aspects Q.200O-Q.2099 ling network protocols Q.220O-Q.2299 Q.260o-Q.2699 Q.270O-Q.2899 Q.290O-Q.2999 gAWaapdti Mur user
6、s of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. 11 2 3 4 5 ITU-T 4.2150.0 (2001), Generic signall
7、ing transport service. ITU-T 4.21 10 (1994), B-ISDNATM adaptation layer - Service specific connection oriented protocol (SSCOP) . ITU-T 4.21 11 (1999), B-ISDN ATM adaption layer - Service specific connection oriented protocol in a multi-link and connectionless environment (SSCOPMCE). ITU-T X.200 (19
8、94), Information technology - Open Systems Interconnection - Basic reference model: The basic model. ITU-T X.210 (1993), Information technology - Open Systems Interconnection - Basic reference model: Conventions for the definition of OSI services. ITU-T 4.2150.2 (05/2001) 1 2.2 Bibliography The foll
9、owing ITU-T Recommendations and other publications contain information that may be useful to understanding the usage of this Recommendation. There are no additional provisions of this Recommendation derived from these publications. ITU-T 4.2630.1 (1999), AAL type 2 signallingprotocol - Capability Se
10、t 1. ITU-T 4.2630.2 (2000), AAL type 2 signallingprotocol - Capability Set 2. ITU-T Q. 1901 (2000), Bearer independent call control protocol. ITU-T Q. 1902.1 (2001), Bearer independent call control protocol (CS2) functional description. ITU-T 1.363.2 (2000), B-ISDN ATMAdaptation Layer specification
11、Type 2 AAL. ITU-T 1.363.5 (1996), B-ISDNATMAdaptation Layer specijication Type 5 AAL. ITU-T 1.366.1 (1998), Segmentation and Reassembly Service Specijc Convergence Sublayer for the AAL Type 2. ITU-T 4.704 (1996), Signalling network functions and messages. ITU-T 4.2210 (1996), Message transfer part l
12、evel 3 functions and messages using the services of ITU-T Recommendation Q.2140. IETF RFC 79 1 (198 i), Internet Protocol. JETF RFC 2474 (1998), Definition of the Diyerentiated Services Field (OS Field) in the IPv4 and IPv6 Headers. Definitions This Recommendation is based upon the concepts develope
13、d in IT-T X.200 4, X.210 5 and in ITU-T 4.21 10 2; in particular, this Recommendation makes use of the following terms defined in a) Service Specific Coordination Function; b) ITU-T 4.21 10 2: Service Specific Connection Oriented Protocol. 4 Abbreviations This Recommendation uses the following abbre
14、viations: AAL ATM Adaptation Layer ATM Asynchronous Transfer Mode B-ISDN Broadband Integrated Services Network BR Buffer Release CPCS Common Part Convergence Sublayer Mu Message Unit PDU Protocol Data Unit PICS Protocol Implementation Conformance Statement SAAL Signalling AAL SAP Service Access Poin
15、t SAR Segmentation and Reassembly Sublayer 2 ITU-T 4.2150.2 (05/2001) sc SDL SDU SN SSCF SSCF-UNI SSCOP SSCOPMCE SSCOP-uu sscs SSSAR SSTED STC SUD UNI Sequence Control Specification and Description Language Service Data Unit Sequence Number Service Specific Coordination Function Service Specific Coo
16、rdination Function for Support of Signalling at the User Network Interface Service Specific Connection Oriented Protocol (ITU-T 4.2 1 1 O 2) Service Specific Connection Oriented Protocol in a Multi-link or Connectionless Environment (ITU-T 4.21 1 1 3) SSCOP User-to-User Information Service Specific
17、Convergence Sublayer Service Specific Segmentation and Reassembly sublayer Service Specific Transmission Error Detection sublayer Signalling Transport Converter STC User Data User Network Interface 5 General description of the signalling transport converter on SSCOP 5.1 The sublayer providing the Si
18、gnalling Transport Converter (STC) resides on top of the Service Specific Convergence Sublayer (SSCS) of the ATM Adaptation Layer (AAL). It uses the services provided by the Service Specific Connection-Oriented Protocol (SSCOP) defined in IT-T 4.21 10 2 and ITU-T 4.21 11 3. SSCOP also resides in the
19、 SSCS. In the SSCS, the Service Specific Coordination Function is “Null“ in the sense that the primitives for the AAL are equivalent to the SSCOP primitives (see 6.2) but identified as AAL-primitives instead of AA-signals consistent with the primitive naming convention at a SAP (see 6. U4.2 1 10 2).
20、 The STC provides the service that is requested by the Generic Signalling Transport Service defined in IT-T Q.2150.0 i, where the signalling protocol makes use of this service. The STC is relying on the assured data transfer service of SSCOP; it may utilize any protocol stack that provides the SSCOP
21、 service; this is illustrated in Figure 5- 1. This Recommendation specifies: Structure of the signalling transport converter on SSCOP sublayer o the interactions between the STC and the signalling protocol entity, the interactions between the STC and the SSCOP sublayer, and the interactions between
22、the STC and layer management. o o ITU-T 4.2150.2 (092001) 3 Signalling Application Signalling Transport Converter on SSCOP and SSCOPMCE (this Recommendation) SSSAR/SSTED ITU-T 1.366.1 ITU-T 1.363.2 ITU-T 1.363.5 I I I SSCOPMCE -TQ.2111 IP DIFFSERV IETFRFC 791 IETF RFC 2474 T1111275oO1 NOTE 1 - The S
23、ervice Access Points shown in this diagram are for modelling purposes only. They are not necessarily visible or accessible from outside. NOTE 2 - There may exist more protocol stacks providing the AAL. type 5 CPCS service than shown. Figure 5-1/Q.2150.2 - Structure of the signalling transport conver
24、ter on SSCOP deploying different protocol stacks 5.2 The STC provides for the transparent transfer of data, i.e. signalling application (STC user) data between peer STC users. The supporting communication resources to achieve this transfer stay invisible to the signalling application. In particular,
25、 the STC service provides for: a) Services provided by the STC Independence fi-om the underlying transmission media: The STC service relieves its users from all concerns of the manner in which the STC service is provided. Except for possible influences of the quality of service, the transfer of data
26、 over different underlying networks is, thus, invisible. Transparency of the information transferred The STC service provides for the transparent transfer of octet-aligned STC user data. It does not restrict the content, format, or coding of the information nor is there ever a need to interpret its
27、structure or meaning. b) 4 ITU-T Q.2150.2 (05/2001) c) Connection establishment and release: The STC service provides for a permanent connection service. As the underlying service (SSCOP) needs to have a connection established, the STC establishes and maintains this connection on behalf of its user;
28、 the user is informed about the availability of the assured data transfer service. NOTE - The establishment of any connection below the SSCOP is outside the scope of this Recommendation. 5.3 Functions of the STC The STC performs the following functions: a) Connection establishment and maintenance: T
29、his function provides for the establishment and maintenance of an SSCOP-connection. Upon a connection release by SSCOP, a connection re-establishment is attempted. NOTE - The connection below the sublayer specified in ITU-T Q.2110 2 and IT-T 4.21 11 3 may be established either on demand or permanent
30、ly. Connection availability reporting to the STC user: This function reports the availability or unavailability of the SSCOP-connection to the user of the STC. Maximum length indication to the STC user: This function indicates to the STC user the maximum length of the PDU that the STC can transfer;
31、it is indicated at creation of the STC entity. CIC control indication to the STC user: This function indicates to the STC user, at creation of the STC entity, whether it serves as the controlling node of the call association. b) c) d) In addition, the following SSCOP services are utilized (see ITU-T
32、 4.21 10 2): e) Sequence Integrity of STC-SDUs; f) Error Correction of STC-SDUs; g) Flow Control of STC-SDUs; h) Keep alive. 6 Elements for layer-to-layer communication 6.1 The Generic Signalling Transport Service is specified in ITU-T Q.2150.0 i. For convenience, a summary of the primitives for acc
33、essing the service is reproduced in Table 6- 1. In the event of any difference between this table and the definitions in U-TQ.2150.0, the definitions in ITU-T 4.2 150.0 take precedence. The generic signalling transport service ITU-T 4.2150.2 (092001) 5 Table 6-UQ.2150.2 - Primitives and parameters o
34、f the generic signalling transport sublayer Generic Name STC User Data NOTE 1 - This primitive has no parameters. NOTE 2 - This parameter is a national option (and the use of this parameter is not supported by this signalling transport). On the establishment of a Signalling Transport Converter entit
35、y and the associated Signalling Transport Converter user entity, for example at power up, the initial conditions are the same as if an OUT-OF-SERVICE.indication primitive had been conveyed across this SAP. Also at this time the START-INFOhdication is sent to the signalling entity. 6.2 The service pr
36、ovided by SSCOP This clause specifies the information flow across the Signalling Transport Converter-AAL Service Specific Convergence Sublayer (SSCOP) boundary. This boundary is defined in 6.UQ.2110 2 and summarized below. In the event of any difference between the following summary and the definiti
37、ons in -T 4.2 1 1 O, the definitions in IT-T 4.2 1 1 O take precedence. The primitives and parameters between STC and SSCOP are defined in Table 6-2. NOTE - This service corresponds to the “Specific Signalling Transport Service“ in Figure 5-1/Q.2150.0. 6.2.1 Primitive definition The definition of th
38、ese primitives is as follows: a) AAL-ESTABLISH: The AAL-ESTABLISH primitives are used to establish a point-to-point connection for assured information transfer between peer user entities. b) AAL-RELEASE: The AAL-RELEASE primitives are used to terminate a point-to-point connection for assured informa
39、tion transfer between peer user entities. c) AAL-DATA: The however, to provide robustness the indication and response primitives are specified nevertheless. 6 ITU-T 4.2150.2 (05/2001) e) AAL-RECOVER The AAL-RECOVER primitives are used during recovery from protocol errors. NOTE2-In the absence of pro
40、tocol errors, the AAL-RECOVER primitives will not be used; however, to provide robustness the indication and response primitives are specified nevertheless. NOTE 3 - The AAL-UNITDATA, AAL-RETRIEVE, and AAL-RETRIEVE-COMPLETE primitives are not used by the protocol entity specified in this Recommendat
41、ion. Indication Response SSCOP-uu SSCOP-uu SSCOP-uu - Source Mu - 00s (Note 3) SN BR Table 6-2/Q.2150.2 - SSCOP primitives and parameters I Confirm SSCOP-uu (Notes 1 and2) - Request Primitive Generic Name SSCOP-uu (Note 1) AAL-ESTABLISH SSCOP-uu I BR (Note 1) (Notes 1 and2) (Note 1) - AAL-RELEASE SS
42、COP-uu AAL-DATA MU 00s (Note 3) _ AAL-RESYNC SSCOP-uu I (Note2) AAL-RECOVER I - AAL-RETRIEVE RN I Note2) - I AAL-RETRIEVE COMPLETE - This primitive is not defined. NOTE 1 -This primitive has no parameters. NOTE 2 - This primitive is not used by the STC and is included here for completeness. NOTE 3 -
43、 This optional parameter is defined only in I7IU-T 4.21 1 1 ; as it is not used by this STC, it is not present in the primitives. 6.2.2 Parameter definition Table 6-2 lists the parameters associated with each SSCOP primitive. The defhition of the parameters is as follows: a) Buffer Release (BR): The
44、 STC does not make use of the functionality of this parameter. In both, the AAL-ESTAE3LISH.request and AAL-ESTABL1SH.response primitives, this parameter is set to “Yes“. The Message Unit parameter is used during information transfer to convey a variable-length message. In AAL-DATA.request primitives
45、, this parameter is mapped transparently into the Information field of an SSCOP PDU. For AAL-DATAhdication primitives, this parameter contains the contents of the information field of the received SSCOP PDU. b) Message Unit 0: ITU-T 4.2150.2 (05/2001) 7 6.3 Out-of-sequence delivery (00s): The STC do
46、es not make use of the functionality of this optional parameter. In both, the AAL-DATA.request and AAL-DATAhdication primitives, this parameter is not included in the primitive. NOTE - This parameter is only defined in SSCOPMCE (ITU-T 4.21 11 3). Sequence Number (SN): The STC does not make use of th
47、is parameter. When receiving it in the DATAkdication primitive, this parameter is ignored. Source: The source parameter indicates to the SSCOP user whether the SSCOP layer or the peer SSCOP user originated the connection release. This parameter assumes one of two values: “SSCOP“ or “User“. If “SSCOP
48、“ is indicated, the user should disregard the SSCOP-UU parameter, if present. SSCOP User-to-User Information (SSCOP-U): The STC does not make use of this parameter. When issuing “request“ or “response“ primitives, this parameter has length zero; on receiving it in “indication“ or “codm“ primitives,
49、this parameter is ignored. Primitives between the STC and layer management Error indications to layer management are performed by the lower layers and no additional error indications are required from the STC. No primitives between the STC and layer management need to be defined. 6.4 State transition diagram for sequences of primitives at the layer boundaries of the STC This clause defines the constraints on the sequences in which the primitives may occur at the layer boundaries of the STC. The sequences are related to the
