ATIS 1000112-2005 Signaling System Number 7 (SS7) - Signaling Connection Control Part (SCCP).pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000112.2005 (R2015) Signaling System Number 7 (SS7) Signaling Connection Control Part (SCCP) As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressi

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11、ges 1-1 1-32) ATIS-1000112.2 Definitions and Functions of Signaling Connection Control Part Messages; (pages 2-1 2-13) ATIS-1000112.3 Signaling Connection Control Part Formats and Codes; (pages 3-1 3-108) ATIS-1000112.4 Signaling Connection Control Part Procedures; (pages 4-1 4-180) ATIS-1000112.5 S

12、ignaling Connection Control Part Performances; (pages 5-1 5-11) ATIS-1000112.6 Signaling Connection Control Part Users Guide (Informative) (pages 6-1 6-27) Changes and additions incorporated into these specifications consist of the following: Addition of new Translation Type Code “18” for ECS Call R

13、outing. The overall and detailed organization of these specifications parallels that used in the equivalent ITU-T Recommendations. Thus ATIS-1000112.1 through ATIS-1000112.5 of this standard correspond to Recommendations Q.711 through Q.714 and Q.716 of the ITU-T specification. ATIS-1000112.6 corres

14、ponds to Q.715. This standard is intended for use in conjunction with T1.110-1999 (R2005), Signaling System Number 7 (SS7) - General information, which includes an overview of SS7, a glossary, and a chapter on abbreviations. Information contained in a normative annex in these specifications is consi

15、dered part of this standard. Information contained in an informative annex in these specifications is not considered part of this standard but is rather auxiliary to the standard. Similarly, footnotes are not part of this official standard. Caution should be exercised in using the Specification and

16、Description Language (SDL) diagrams to interpret the standard; please note that the text always takes precedence over the SDL. Future control of this document will reside with Accredited Standards Committee on Telecommunications, Alliance for Telecommunications Industry Solutions. This control of ad

17、ditions to the specification, such as ongoing protocol evolution, new applications, and operational requirements, will permit compatibility among U. S. networks. Such additions will be ATIS-1000112.2005 iii incorporated in an orderly manner with due consideration to the ITU-T layered model principle

18、s, conventions, and functional boundaries. Suggestions for improvement of this standard will be welcome. They should be sent to the Alliance for Telecommunications Industry Solutions, 1200 G Street, NW, Suite 500, Washington, DC 20005. This standard was processed and approved for submittal to ANSI b

19、y the Accredited Standards Committee Packet Technologies and Systems Committee (PTSC). Committee approval of this standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the PTSC had the following members: B. Hall, PTSC Chair J. Z

20、ebarth, PTSC Vice-Chair S. Carioti, ATIS Disciplines S. Barclay, ATIS Secretariat C. Underkoffler, ATIS Chief Editor C. Brownmiller, ATIS Technical Editor R. Singh, PTSC Technical Editor Organization Represented Name of Representative AcmePacket Kevin Klett Alcatel USA Inc. Ken Biholar AT and 2. A t

21、ransfer capability for signaling data units with or without the use of logical signaling connections. Functions of the SCCP are used for the transfer of circuit related and non circuit-related signaling information of the ISDN User Part with or without setup of end-to-end signaling connections. Thes

22、e functions are described in ATIS-1000112.4 and ATIS-1000113.4. Figure 1/ATIS-1000112.1 illustrates the embedding of the SCCP within the common-channel signaling system. 1.3 General Characteristic 1.3.1 Technique of Description The SCCP is described in terms of: 1. Services provided by the SCCP. 2.

23、Services assumed from the MTP. 3. Functions of the SCCP. The functions of the SCCP are performed by means of the SCCP protocol between two systems which provide the SCCP service to the user located above the SCCP layer. The service interfaces to the upper ATIS-1000112.1.2005 1-2 layers and to the MT

24、P are described by means of primitives and parameters. Figure 2/ATIS-1000112.1 illustrates the relationship between the SCCP protocol and the adjacent services. 1.3.2 Primitives Primitives consist of commands and their respective responses associated with the services requested of the SCCP and of th

25、e MTP, see Figure 3/ATIS-1000112.1. The general syntax of a primitive is shown below: X Generic Name Specific Name Parameters 1. “X“ designates the functional block providing the service (“MTP“ for MTP, “N“ for SCCP) 2. “Generic Name“ describes the action that should be performed by the addressed la

26、yer 3. “Specific Name“ indicates the direction of the primitive flow 4. “Parameters“ are the elements of information which are to be transmitted between layers. Four Specific Names exist in general, see Figure 4/ATIS-1000112.1: Request Indication Response Confirm Not all four Specific Names are asso

27、ciated with Generic Names (see Table 1/ATIS-1000112.1 and Table 8/ATIS-1000112.1). 1.3.3 Peer-to-Peer Communication Exchange of information between two peers of the SCCP is performed by means of a protocol. The protocol is a set of rules and formats by which the control information (and user data) i

28、s exchanged between the two peers. The protocol provides for: 1. The setup of logical signaling connections 2. The release of logical signaling connections 3. The transfer of data with or without logical signaling connections. A signaling connection is modeled in the abstract by a pair of queues. Th

29、e protocol elements are objects on that queue added by the origination SCCP user and removed by the destination SCCP user. Each queue represents a flow control function. Figure 5/ATIS-1000112.1 illustrates the modes described above. (Model for the connectionless service is for further study.) ATIS-1

30、000112.1.2005 1-3 1.3.4 Contents of ATIS-1000112 Chapter 1 contains a general description of the services provided by the MTP, the services provided by the SCCP and the functions within the SCCP. Chapter 2 defines the set of protocol elements and their embedding into messages. Chapter 3 describes th

31、e formats and codes used for the SCCP messages. Chapter 4 is a detailed description of the SCCP procedures as a protocol specification. Chapter 5 provides the performance requirements for the SCCP. Chapter 6 provides the SCCP Users Guide (Informative). 2 SERVICES PROVIDED BY THE SCCP The overall set

32、 of services is grouped into: 1. Connection-oriented services; and 2. Connectionless services. Four classes of services are provided by the SCCP protocol: two for connectionless services and two for connection-oriented services. The four classes are: 0 Basic connectionless class. 1 In-sequence deliv

33、ery connectionless class. 2 Basic connection-oriented class. 3 Flow control connection-oriented class. In the tables defining individual primitives, the notations given below are used: M indicates a mandatory parameter; O indicates an SCCP implementation option; C indicates that the parameter is con

34、ditional; U indicates a user option; and = indicates the parameter must have the same value in the indication primitive, or confirm primitive as provided in the corresponding request primitive, or response primitive, respectively. 2.1 Connection-Oriented Services A distinction has to be made between

35、: 1. Temporary signaling connections; and 2. Permanent signaling connections. Temporary signaling connection establishment is initiated and controlled by the SCCP user. Temporary signaling connections are comparable with dialed telephone connections. Permanent signaling connections are established a

36、nd released by Management and are provided to the SCCP user on a semi-permanent basis (comparable with leased telephone lines), while data including reset is under control of the SCCP user. Further details are given in clause 2.1.1. ATIS-1000112.1.2005 1-4 2.1.1 Temporary Signaling Connections 2.1.1

37、.1 Description The control of a signaling connection is divided into the following phases: 1. Connection establishment phase 2. Data transfer phase 3. Connection release phase. 2.1.1.1.1 Connection Establishment Phase Connection establishment procedures provide the mechanism for establishing tempora

38、ry signaling connections between users of the SCCP. A signaling connection between two SCCP users may consist of one or more connection sections. A signaling connection between two SCCP users in the same node is considered an implementation dependant matter. During connection establishment, routing

39、functions are provided by the SCCP, in addition to those provided by the MTP. At intermediate nodes, SCCP routing determines whether a signaling connection should be realized by one connection section or several concatenated connection sections. The criteria for deciding on several concatenated conn

40、ection sections are implementation dependant. For Connection establishment there are two alternative boundaries between SCCP and SCCP user with different procedures; The “X.213-like” boundary that is described further in clause 2.1.1.2; and The “ISUP-embedded” boundary that is described further in c

41、lause 2.1.1.3. The “X.213-like” boundary requires that establishment procedures are performed by SCCP while in the case of “ISUP-embedded” boundary the ISUP provides the routing of the request for the set-up of a connection section. The connection refusal procedure is invoked if the SCCP or the SCCP

42、 user is unable to establish a signaling connection. 2.1.1.1.2 Data Transfer Phase The data transfer service provides for an exchange of user data, called Network Service Data Units (NSDU), in either direction or in both directions simultaneously on a signaling connection. Each NSDU is characterized

43、 by a connection identification which allocates the message to a certain signaling connection. The data transfer service provides for segmenting of messages, concatenation of messages, flow control, error detection, sequence control, and other functions, depending on the quality of service required

44、by the SCCP user (two different classes of the connection-oriented service are provided by the protocol, see ATIS-1000112.4). ATIS-1000112.1.2005 1-5 2.1.1.1.3 Connection Release Phase Connection release procedures provide the mechanism for releasing temporary signaling connections between users of

45、the SCCP. The signaling connection may be released by both or either of the SCCP users. The signaling connection may also be released by the SCCP if the connection can not be maintained. 2.1.1.2 Network Service Primitives and Parameters Applicable To The X.213-Like Connection-Oriented Boundary 2.1.1

46、.2.1 Overview Table 1/ATIS-1000112.1 gives an overview of the primitives to the upper layers and the corresponding parameters for the (temporary) connection-oriented network service. Figure 6/ATIS-1000112.1 shows an overview state transition diagram for the sequence of primitives at a connection end

47、point. A more detailed description for the primitives and their parameters is given in the following chapters. 2.1.1.2.2 Connection Establishment Phase A network service user (calling user) initiates the setup of the connection by means of the primitive “N-CONNECT request“ to the SCCP. The SCCP enti

48、ty evaluates the primitive and adds the protocol control information. The SCCP message - consisting of the protocol control information (PCI) and possibly an NSDU - is transmitted by means of the MTP-services to the remote peer entity of the SCCP. It evaluates and strips the PCI, and sends a primiti

49、ve “N-CONNECT indication“ to the local network service user. On both ends of the connection the status “pending“ is assumed. The called SCCP user answers with the primitive “N-CONNECT response“ to the local SCCP, which sends the response SCCP message, including PCI, to the calling SCCP. The calling SCCP sends the primitive “N-CONNECT confirm“ to the calling SCCP user. The connection is now ready for data transfer. The four types of N-CONNECT applicable to the X.213-like boundary, the “request,“ the “indication,“ the “response,“ and the “confirm,“ contain the p