1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TE LEC0 MM UN I CATI0 N STANDARDIZATION SECTOR OF ITU SERIES Q: SWITCHING AND SIGNALLING Q.1901 (O 6/20 00) Bearer independent call control protocol ITU-T Recommendation Q.1901 (Formerly CCITT Recommendation) COPYRIGHT International Telecommunications Unio
2、n/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE NERNATIONAL MANUAL SERVICE FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 SPECIFICATIONS OF SIGNAL
3、LING SYSTEM No. 6 SPECIFICATIONS OF SIGNALLING SYSTEM R1 SPECIFICATIONS OF SIGNALLING SYSTEM R2 DIGITAL EXCHANGES INTERWORIUNG OF SIGNALLING SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q3 INTERFACE DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 PUBLIC LAND MOBILE NETWORK INTERWORIUNG WITH SATELLIT
4、E MOBILE SYSTEMS INTELLIGENT NETWORK BROADBAND ISDN INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q.lLQ.3 Q.4-Q.59 Q.60.99 Q.lO all users of this Recommendation are therefore encouraged to investigat
5、e 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. ITU-T 4.761 (1999), Signalling system No. 7 - ISDN User Part functional description. ITU-T 4.762 (1999), Signall
6、ing system No. 7 - ISDN User general functions of messages and signals. ITU-T 4.763 (1999), Signalling system No. 7 - ISDN User Part formats and codes. ITU-T 4.764 (1999), Signalling system No. 7 - ISDN User Part signallingprocedures. ITU-T 4.730 (1999), ISDN User Part supplementary services. ITU-T
7、4.765.5 (2000), Signalling system No. 7 -Application transport mechanism: Bearer Independent Call Control (BICC). ITU-T 4.765 (2000), Signalling system No. 7 -Application Transport Mechanism. ITU-T 4.724 (1988), Telephone user part signallingprocedures. ITU-T Q. 1 15 (1999), Logic for the control of
8、 echo control devices. ITU-T 4.766 (1993), Performance objectives in the integrated services digital network application. ITU-T 4.701 (1993), Functional description of the message transfer part (2MTP) of Signalling system No. 7. ITU-T 4.704 (1996), Signalling network functions and messages. ITU-T 4.
9、2210 (1996), Message Transfer Part Level 3 Functions and Messages using the Services of ITU-T Recommendation Q.2140. ITU-T 4.21 10 (1994), B-ISDN ATM adaptation layer - Service specific connection oriented protocol (SSCOP). ITU-T 4.21 11 (1999), Service specific connection oriented protocol in a mul
10、ti-link and connectionless environment (SSCOPMCE). 2 ITU-T 0.1901 (06/2000) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services3 Definitions This Recommendation defines the following terms: 3.1 Bearer Control Function (BCF): Four types of
11、BCF are defined; BCF-N, BCF-T, BCF-G and BCF-R. The BCF-N, BCF-T and BCF-G provide the control of the bearer switching function, the communication capability with its associated CSF, and the signalling capability necessary for the establishment and release of the bearer to its peer. The BCF-R provid
12、es the control of the bearer switching function and relays the bearer control signalling requests to next BCF in order to complete the end-to-end bearer control signalling action. The BCF is not within the scope of this Recommendation. 3.2 Bearer Interworking Function (BIWF): A functional entity whi
13、ch provides bearer control functions (BCF) and media mappinghwitching functions within the scope of a Serving Node (SN). A BIWF contains one BCF. 3.3 without an associated BCF entity. 3.4 Call Mediation Node (CMN): A functional entity which provides CSF functionality Call Service Function (CSF): Fou
14、r types of CSF are defined: associated with the narrow-band service by interworking with narrow-band and bearer independent signalling, signalling to its peer CSF the characteristics of the call, and invoking the Bearer Control Nodal Functions (BCF-N) necessary to transport the narrow-band bearer se
15、rvice across the backbone network. establish and maintain a backbone network call (see Figure 2), and its associated bearer by relaying signalling between CSF peers and invoking the Bearer Control Transit Functions (BCF-T) necessary to transport the narrow-band bearer service across the backbone net
16、work. to establish and maintain a backbone network call and its associated bearer by relaying signalling between CSF peers and invoking the Bearer Control Gateway Functions (BCF-G) necessary to transport the narrow-band bearer service between backbone networks. mediation actions necessary to establi
17、sh and maintain a backbone network call by relaying signalling between CSF peers. The CSF-C has no association with any BCF. It is only a call control function. 3.5 constructor: An information element type, the contents of which consists of other information elements, as described in ITU-T 4.765.5.
18、The Call Service Nodal Function (CSF-N) provides the service control nodal actions The Call Service Transit Function (CSF-T) provides the service transit actions necessary to The Call Service Gateway Function (CSF-G) provides the service gateway actions necessary The Call Service Coordination Functi
19、on (CSF-C) provides the call coordination and 3.6 Gateway Serving Node (GSN): A functional entity which provides gateway functionality between two network domains. This functional entity contains the call service function (CSF-G), and one or more bearer interworking functions (BIWF). GSNs interact w
20、ith other GSNs, in other backbone network domains and other ISNs and TSNs within its own backbone network domain. 3.7 Interface Serving Node (ISN): A functional entity which provides the interface with SCNs. This functional entity contains the call service nodal function (CSF-N), and one or more bea
21、rer interworking functions (BIWF) which interact with the SCN and its peers within the backbone network. 3.8 list of supported codecs: List of codecs conveyed between two SNs. It includes all the codecs that are supported from the SN initiating codec negotiation procedures up to the SN sending the m
22、essage including the list of codecs. ITU-T 0.1901 (06/2000) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services3.9 list of available codecs: This list contains all the codecs that can be used for the call Set-up and in the active phase o
23、f the call. 3.10 Signalling Transport Layers (STL): Any suite of protocol layers currently specified to provide Transport andor Network Layer services to the BICC. Their functions, protocol and service primitives are outside the scope of this Recommendation. 3.11 Serving Node (SN): A functional enti
24、ty that is either an ISN, a GSN or a TSN. 3.12 Signalling Transport Converter (STC): A protocol layer between the STL and BICC. This layer enables the BICC protocol to be independent of the STL being used. 3.13 simple: An information element type, as described in ITU-T 4.765.5. 3.14 Switching Node (
25、SWN): A functional entity which provides the switching functions within the backbone core network. This functional entity contains a BCF-R. SWNs interact with other SWNs and BIWFs, within their own backbone network domain. 3.15 Switched Circuit Network (SCN): Generic term for any network that uses c
26、ircuit switching technology, i.e. ISDN, PSTN, PLMN. 3.16 Transit Serving Node (TSN): A functional entity which provides transit functionality between two SNs. This functional entity contains the call service function (CSF-T), and supports one or more bearer interworking functions (BIWF). TSNs intera
27、ct with other TSNs, GSNs and ISNs within their own backbone network domain. 4 Abbreviations This Recommendation uses the following abbreviations: ACM Address Complete Message AEI Application Entity Invocation APM Application Transport Mechanism APP Application Transport Parameter ASE Application Ser
28、vice Element AT11 Application Transport Instruction Indicators BAT Bearer Association Transport BCF Bearer Control Function BCF-G Bearer Control Gateway Function BCF-N Bearer Control Nodal Function BCF-T Bearer Control Transit Function BICC Bearer Independent Call Control BIWF Bearer Interworking Fu
29、nction BNC-ID Backbone Network Connection Identifier CIC Call Instance Code (BICC) CIC Circuit Identification Code (ISUP) CMN Call Mediation Node COT Continuity message 4 ITU-T 0.1901 (06/2000) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Se
30、rvicesCPG CSF CSF-C CSF-G CSF-N CSF-T DPC EH GRS GSN IAM ISDN ISN ISUP LSB MLPP MSB MTP M“3 MTP3b NI OPC PLMN PSTN REL RLC RSC SACF SAM SA0 SCN SI SI0 SLS SN STC STL Call Progress message Call Service Function Call Service Coordination Function Call Service Gateway Function Call Service Nodal Functi
31、on Call Service Transit Function Destination Point Code Errors Handling Group Reset message Gateway Serving Node Initial Address Message Integrated Services Digital Network Interface Serving Node ISDN User Part Least Significant Bit Multi-Level Precedence and Pre-emption Most Significant Bit Message
32、 Transfer Part Message Transfer Part level 3 (Narrow band) Message Transfer Part level 3 (Broadband) Network Indicator (in SIO), or Network Interface (in specification model) Originating Point Code Public Land Mobile Network Public Switched Telephone Network RELease message ReLease Complete message
33、Reset Circuit message Single Association Control Function Subsequent Address Message Single Association Object Switched Circuit Network Service Indicator Service Information Octet Signalling Link Selection Serving Node Signalling Transport Converter Signalling Transport Layers ITU-T Q.1901 (06/2000)
34、 5 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSwitching Node Terminal Equipment Transit Serving Node Conventions The name of each element of the following classes of terms is capitalized indicators; parameters; information elements
35、; messages. Examples: Called Party Number parameter, Initial Address message. The definition of a parameter value is written in italics and is put between quotation marks. Example: Nature of Address value O00001 1 - “national (significant) number“. All message names are BICC messages unless explicit
36、ly stated otherwise. Example: The “IAM message“ is the IAM message in BICC, whereas an IAM message in ISUP is referred to as an “ISUP IAM message“. NOTE- Where the text has been imported from other Recommendations then the conventions of this Recommendation do not automatically apply. 6 Architecture
37、 6.1 Network model Figure 2 shows the complete functional model of a network using the BICC protocol for call control signalling. 6 ITU-T Q.1901 (06/2000) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesFigure 2/Q.1901- Network Function
38、al model NOTE - The functionality of the CMN is not currently defined - see Appendix III. 6.2 Protocol model Figure 3 shows the protocol model adopted for this Recommendation. Figure 3/Q.1901 - Protocol model ITU-T 0.1901 (06/2000) 7 COPYRIGHT International Telecommunications Union/ITU Telecommunica
39、tionsLicensed by Information Handling ServicesThe protocol aspects of the functional model in Figure 2 are provided by the elements of the protocol model in Figure 3. The BICC procedures block includes the functions of the CSF element in the functional The protocol functions of the BCF element of th
40、e functional model are distributed between model. the Mapping Function, and Bearer Control blocks in Figure 3. The other functions included in the BCF element, e.g. control of switching functions, are not shown in Figure 3. BCF, this relates to use of the generic interface to the mapping function bl
41、ock in Figure 3. use of the generic interface to the Signalling Transport Converter, described in Annex B. Where the BICC description refers to sendingheceiving bearer signalling events to/fi-om the Where the BICC description refers to sendingheceiving BICC messages, this relates to the 6.3 Recommen
42、dation structure This Recommendation describes procedures that are generally relevant to the BICC protocol, independent of the bearer technology employed. This is the block labelled BICC procedures in Figure 3. It also uses the generic interface to the blocks labelled Mapping Functions and Signallin
43、g Transport Converter. The blocks in Figure 3 labelled Mapping Function are defined in additional publications that are to be provided for each bearer technology to describe specific adaptation for that technology. The blocks in Figure 3 labelled Signalling Transport Converter are defined in the Ann
44、exes of this Recommendation which describe the general and transport specific issues relating to the STC. The following clauses of this Recommendation describe the BICC protocol as a series of exceptions to ITU-T 4.761 to 4.765. 7 Exceptions to ITU-T Q.761 7.1 General The BICC protocol is an adaptat
45、ion of the ISUP protocol definition, but it is not peer-to-peer compatible with ISUP. The BICC protocol does include the compatibility mechanism of ISUP and a similar mechanism within the BICC APM user application. Thus: 1) Peer-to-peer compatibility of versions of BICC can be assured, as described
46、for ISUP in clause 6/Q.761. 2) The compatibility mechanism at a Serving Node (ISN/TSN/GSN) acts as at an ISUP exchange, and thus the introduction of BICC into a network using ISUP signalling does not degrade the ability to introduce new signalling versions into the network, e.g. an ISN receiving an
47、unrecognized ISUP parameter will handle it according to 2.9.YQ.764, Compatibility rules, passing it on to BICC if required. 7.2 BICC uses an APM user application to transfer signalling information. Thus, in order to provide forward and backward compatibility within BICC, a compatibility mechanism is
48、 introduced for the information elements transferred by this mechanism. Forward and Backward Compatibility for the BICC APM user application See Bibliography. 8 ITU-T 0.1901 (06/2000) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesThis
49、 compatibility mechanism remains unchanged for all capability sets andor subsets of the BICC protocol defined in this Recommendation. It is based on compatibility information sent with all signalling information. The compatibility method eases the network operation, for example: for the typical case of a BICC signalling protocol mismatch during a network upgrading; to interconnect two networks at different functional levels; for networks using different subsets of the same BICC protocol, etc. NOTE - A node may be at a different functional level due to having implemented a different capabilit
