Recommendation Q.713 SCCP FORMATS AND CODES 1 General The Signalling Connection Control Part (SCCP) messages are carried on the signalling data link by means of Signal Units the format of which is described in Recommendation Q.703, S 2.2. The Service Information Octet format and coding is described in Recommendation Q.704, S 14.2. The Service Indicator is coded 0011 for the SCCP. The Signalling Information Field (SIF) of each Message Signal Unit containing an SCCP message consists of an integral number of octets. A message consists of the following parts (see Figure 1/Q.713): - the routing label; - the message type code; - the mandatory fixed part; - the mandatory variable part; - the optional part, which may contain fixed length and variable length fields. The description of the various parts is contained in the following sections. SCCP Management messages and codes are provided in S 5 of this Recommendation. 1.1 Routing label The standard routing label specified in Recommendation Q.704, S 2.2 is used. The rules for the generation of the signalling link selection (SLS) code are described in Recommendation Q.711, S 2.2.1. Routing label Message type code Mandatory fixed part Mandatory variable part Optional part FIGURE 1/Q.713 General layout Fascicle VI.7 - Rec. Q.713 PAGE1 1.2 Message type code The message type code consists of a one octet field, and is mandatory for all messages. The message type code uniquely defines the function and format of each SCCP message. The allocation of message type codes, with reference to the appropriate descriptive section of this Recommendation is summarized in Table 1/Q.713. Table 1/Q.713 also contains an indication of the applicability of the various message types to the relevant classes of protocol. 1.3 Formatting principles Each message consists of a number of parameters listed and described in S 3. Each parameter has a "name" which is coded as a single octet (see S 3). The length of a parameter may be fixed or variable, and a "length indicator" of one octet for each parameter may be included as described below. The detailed format is uniquely defined for each message type as described in S 4. A general SCCP message format is shown in Figure 2/Q.713. 1.4 Mandatory fixed part Those parameters that are mandatory and of fixed length for a particular message type will be contained in the "mandatory fixed part". The position, length and order of the parameters is uniquely defined by the message type. Thus the names of the parameters and the length indicators are not included in the message. 1.5 Mandatory variable part Mandatory parameters of variable length will be included in the mandatory variable part. The name of each parameter and the order in which the pointers are sent is implicit in the message type. Parameter names are, therefore, not included in the message. A pointer is used to indicate the beginning of each parameter. Because of this, parameters may be sent in an order different from that of the pointers. Each pointer is encoded as a single octet. The details of how pointers are encoded is found in S 2.3. The number of parameters, and thus the number of pointers is uniquely defined by the message type. A pointer is also included to indicate the beginning of the optional part. If the message type indicates that no optional part is allowed, then this pointer will not be present. If the message type indicates that an optional part is possible, but there is no optional part included in this particular message, then a pointer field containing all zeros will be used. All the pointers are sent consecutively at the beginning of the mandatory variable part. Each parameter contains the parameter length indicator followed by the contents of the parameter. Figure 2/Q.713 - CCITT 73070 1.6 Optional part The optional part consists of parameters that may or may not occur in any particular message type. Both fixed length and variable length parameters may be included. Optional parameters may be transmitted in any order1). Each optional parameter will include the parameter name (one octet) and the length indicator (one octet) followed by the parameter contents. 1.7 End of optional parameters octet After all optional parameters have been sent, an end of optional parameters octet containing all zeroes will be transmitted. This octet is only included if optional parameters are present in the message. 1.8 Order of transmission Since all the parameters consist of an integral number of octets, the formats are presented as a stack of octets. The first octet transmitted is the one shown at the top of the stack and the last is the one at the bottom (see Figure 2/Q.713). Within each octet, the bits are transmitted with the least significant bit first. 1.9 Coding of spare bits According to the general rules defined in Rec. Q.700, spare bits are coded 0 unless indicated otherwise at the originating nodes. At intermediate nodes, they are passed transparently. At destination nodes, they need not be examined. 1.10 National message types and parameters If message type codes and parameter codes are required for national uses, 1) It is for further study if any constraint in the order of transmission will be introduced. PAGE30 Fascicle VI.7 - Rec. Q.713 it is suggested that the codes be selected from the highest code downwards, that is starting at code 11111110. Code 11111111 is reserved for future use. 2 Coding of the general parts 2.1 Coding of the message type The coding of the message is shown in Table 1/Q.713. 2.2 Coding of the length indicator The length indicator field is binary coded to indicate the number of octets in the parameter content field. The length indicator does not include the parameter name octet or the length indicator octet. 2.3 Coding of the pointers The pointer value (in binary) gives the number of octets between the pointer itself (included) and the first octet (not included) of the parameter associated with that pointer2). The pointer value all zeros is used to indicate that, in the case of optional parameters, no optional parameter is present. 3 SCCP parameters The parameter name codes are given in Table 2/Q.713 with reference to the subsections in which they are described. 3.1 End of optional parameters The "end of optional parameters" parameter field consists of a single octet containing all zeros. 3.2 Destination local reference The "destination local reference" parameter field is a three-octet field containing a reference number which, in outgoing messages, has been allocated to the connection section by the remote node. The coding "all ones" is reserved, its use is for further study. TABLE 1/Q.713 SCCP message types Classes Message type 0 1 2 3 S Code CR Connection Request X X 4.2 0000 0001 CC Connection Confirm X X 2) For example, a pointer value of "00000001" indicates that the associated parameter begins in the octet immediately following the pointer. A pointer value of "00001010" indicates that nine octets of information exist between the pointer octet and the first octet of the parameter associated with that pointer. Fascicle VI.7 - Rec. Q.713 PAGE1 4.3 0000 0010 CREF Connection Refused X X 4.4 0000 0011 RLSD Released X X 4.5 0000 0100 RLC Release Complete X X 4.6 0000 0101 DT1 Data Form 1 X 4.7 0000 0110 DT2 Data Form 2 PAGE30 Fascicle VI.7 - Rec. Q.713 X 4.8 0000 0111 AK Data Acknowledgement X 4.9 0000 1000 UDT Unitdata X X 4.10 0000 1001 UDTS Unitdata Service X X 4.11 0000 1010 ED Expedited Data X 4.12 0000 1011 EA Expedited Data Acknowledgement Fascicle VI.7 - Rec. Q.713 PAGE1 X 4.13 0000 1100 RSR Reset Request X 4.14 0000 1101 RSC Reset Confirm X 4.15 0000 1110 ERR Protocol Data Unit Error X X 4.16 0000 1111 IT Inactivity Test X X 4.17 PAGE30 Fascicle VI.7 - Rec. Q.713 0001 0000 X Type of message in this protocol class. TABLE 2/Q.713 SCCP parameter name codes Parameter name S Parameter name code 8765 4321 End of optional parameters 3.1 0000 0000 Destination local reference 3.2 0000 0001 Source local reference 3.3 0000 0010 Called party address 3.4 0000 0011 Calling party address 3.5 0000 0100 Protocol class 3.6 0000 0101 Segmenting/reassembling 3.7 0000 0110 Receive sequence number 3.8 0000 0111 Sequencing/segmenting 3.9 Fascicle VI.7 - Rec. Q.713 PAGE1 0000 1000 Credit 3.10 0000 1001 Release cause 3.11 0000 1010 Return cause 3.12 0000 1011 Reset cause 3.13 0000 1100 Error cause 3.14 0000 1101 Refusal cause 3.15 0000 1110 Data 3.16 0000 1111 PAGE30 Fascicle VI.7 - Rec. Q.713 3.3 Source local reference The "source local reference" parameter field is a three-octet field containing a reference number which is generated and used by the local node to identify the connection section. The coding "all ones" is reserved, its use is for further study. 3.4 Called party address The "called party address" is a variable length parameter. Its structure is shown in Figure 3/Q.713. 8 7 6 5 4 3 2 1 Octet Address indicator 1 Octet 2 . Fascicle VI.7 - Rec. Q.713 PAGE1 . Address . Octet n FIGURE 3/Q.713 Called/Calling party address 3.4.1 Address indicator The "address indicator" indicates the type of address information contained in the address field (see Figure 4/Q.713). The address consists of one or any combination of the following elements: - signalling point code; - global title (for instance, dialled digits); - subsystem number. PAGE30 Fascicle VI.7 - Rec. Q.713 8 7 6 5 4 3 2 1 Reserved Rtg Global title SSN Point code for indicator indicator indicator indicator national use FIGURE 4/Q.713 Address indicator encoding Fascicle VI.7 - Rec. Q.713 PAGE1 A "1" in bit 1 indicates that the address contains a signalling point code. A "1" in bit 2 indicates that the address contains a subsystem number. Bits 3-6 of the address indicator octet contain the global title indicator, which is encoded as follows: Bit 6 5 4 s 3 0 0 0 No global title included 0 0 0 0 Global title includes nature of address indicator 1 only 0 0 1 Global title includes translation type only3) 0 0 0 1 Global title includes translation type, numbering 1 plan and encoding scheme3) 0 1 0 Global title includes translation type, numbering 0 plan, encoding scheme and nature of address indicator 0 1 0  1 to  spare international 0 1 1 θ 1 1 0 0  0 to 3) Full E.164 numbering plan address is used in these two cases for Recommendation E.164 based global titles. PAGE30 Fascicle VI.7 - Rec. Q.713  spare national 1 1 1 θ 0 1 1 1 reserved for extension. 1 When a global title is used in the called party address, it is suggested that the called party address contain a subsystem number. This serves to simplify message reformatting following global title translation. The subsystem number should be encoded "00000000" when the subsystem number is not known, e.g., before translation. Bit 7 of the address indicator octet contains routing information identifying which address element should be used for routing. A "0" in bit 7 indicates that routing should be based on the global title in the address. A "1" in bit 7 indicates that routing should be based on the destination point code in the MTP routing label and the subsystem number information in the called party address. Bit 8 of the address indicator octet is designated for national use. 3.4.2 Address The various elements, when provided, occur in the order: point code, subsystem number, global title, as shown in Figure 5/Q.713. 8 7 6 5 4 3 2 1 Signalling point code Subsystem number Global title FIGURE 5/Q.713 Ordering of address elements 3.4.2.1 Signalling point code The signalling point code, when provided, is represented by two octets. Bits 7 and 8 in the second octet are set to zero (see Figure 6/Q.713). 8 7 6 5 4 3 2 1 Fascicle VI.7 - Rec. Q.713 PAGE1 0 0 FIGURE 6/Q.713 Signalling point code encoding 3.4.2.2 Subsystem number The subsystem number (SSN) identifies an SCCP user function and, when provided, consists of one octet coded as follows: Bit 8 7 6 5 4 3 s 2 1 0 0 0 0 0 0 SSN not known/not used 0 0 0 0 0 0 0 0 SCCP management 0 1 0 0 0 0 0 0 reserved for CCITT allocation 1 0 0 0 0 0 0 0 ISDN user part 1 1 0 0 0 0 0 1 OMAP 0 0 PAGE30 Fascicle VI.7 - Rec. Q.713 0 0 0 0 0 1 MAP (Mobile Application Part) 0 1 0 0 0 0 0 1  1 0 to  spare 1 1 1 1 1 1 θ 1 0 1 1 1 1 1 1 reserved for expansion. 1 1 Network specific subsystem numbers should be assigned in descending order starting with "11111110". 3.4.2.3 Global title4) The format of the global title is of variable length. Figure 7/Q.913, Figure 9/Q.713, Figure 10/Q.713 and Figure 11/Q.713 show four possible formats for global title. 3.4.2.3.1 Global title indicator = 0001 8 7 6 5 4 3 2 1 O/E Nature of address indicator octet 1 Address information octet 2 and further FIGURE 7/Q.713 4) Incorporation of NSAP address in the SCCP global title is for further study. Fascicle VI.7 - Rec. Q.713 PAGE1 Global title format for indicator 0001 Bits 1 to 7 of octet 1 contain the nature of address indicator and are coded as follows: Bit 7 6 5 4 3 2 s 1 0 0 0 0 0 0 spare 0 0 0 0 0 0 0 subscriber number 1 0 0 0 0 0 1 reserved for national use 0 0 0 0 0 0 1 national significant number 1 0 0 0 0 1 0 international number 0 0 0 0 0 1 0  1 to  spare 1 1 1 1 1 1 θ 1 Bit 8 of octet 1 contains the odd/even indicator and is coded as follows: Bit 8 0 even number of address signals 1 odd number of address signals The octets 2 and further contain a number of address signals and possibly PAGE30 Fascicle VI.7 - Rec. Q.713 a filler as shown in Figure 8/Q.713. 8 7 6 5 4 3 2 1 2nd address signal 1st address signal octet 2 4th address signal 3rd address signaloctet 3 . . . filler (if nth address signal octet m necessary) FIGURE 8/Q.713 Address information Fascicle VI.7 - Rec. Q.713 PAGE1 Each address signal is coded as follows: The application of these codes in actual networks is for further study. 0000 digit 0 0001 digit 1 0010 digit 2 0011 digit 3 0100 digit 4 0101 digit 5 0110 digit 6 0111 digit 7 1000 digit 8 1001 digit 9 1010 spare 1011 code 115) 1100 code 125) 1101 spare 1110 spare 1111 ST In case of an odd number of address signals, a filler code 0000 is inserted after the last address signal. 3.4.2.3.2 Global title indicator = 0010 Figure 9/Q.713 shows the format of the global title, if the global title indicator equals "0010". 8 7 6 5 4 3 2 1 Translation type octet 1 Address information octet 2 and further FIGURE 9/Q.713 Global title format for indicator 0010 The translation type is a one-octet field that is used to direct the message to the appropriate global title translation function.6) Thus, it may be possible for the address information to be translated into different values for and different combinations of DPCs, SSNs and GTs. This octet will be coded "00000000" when not used. Translation types for internetwork services will be assigned in ascending order starting with 00000001". Translation types for network specific services will be assigned in descending order starting with "11111110". The code "11111111" is reserved for expansion. However, the exact coding of translation types in the international network is for further study. Additional requirements may be placed on this field as a result of further work on Transaction Capabilities and the ISDN User Part. In the case of this global title format (0010), the translation type may also imply the encoding scheme, used to encode the address information, and the numbering plan. 3.4.2.3.3 Global title indicator = 0011 8 7 6 5 4 3 2 1 Translation type octet 1 Numbering plan Encoding scheme octet 2 Address information 5) The application of these codes in actual networks is for further study. 6) A translation type may for instance imply a specific service to be provided by the SCCP user, such as free phone number translation, or identify the category of service to be provided, for example, dialed number screening, password validation or transmission of digits to telephone network address. PAGE30 Fascicle VI.7 - Rec. Q.713 octet 3 and further FIGURE 10/Q.713 Global title format for indicator 0011 The translation type is as described in S 3.4.2.3.2. The numbering plan is encoded as follows7): Bit 8 7 6 s 5 0 0 0 unknown 0 0 0 0 ISDN/Telephony Numbering Plan (Recommendations E.163 and 1 E.164) 0 0 1 spare 0 0 0 1 Data Numbering Plan (Recommendation X.121) 1 0 1 0 Telex Numbering Plan (Recommendation F.69) 0 0 1 0 Maritime Mobile Numbering Plan (Recommendations E.210, 211) 1 0 1 1 Land Mobile Numbering Plan (Recommendation E.212) 0 0 1 1 ISDN/Mobile numbering plan (Recommendation E.214) 1 1 0 0  0 7) The support of all numbering plans is not mandatory. Fascicle VI.7 - Rec. Q.713 PAGE1 to  spare 1 1 1 θ 0 1 1 1 reserved 1 The encoding scheme is encoded as follows: Bit 4 3 2 s 1 0 0 0 unknown 0 0 0 0 BCD, odd number of digits 1 0 0 1 BCD, even number of digits 0 0 0 1  1 to  spare 1 1 1 θ 0 1 1 1 PAGE30 Fascicle VI.7 - Rec. Q.713 1 reserved. If the encoding scheme is binary coded decimal, the global title value, starting from octet 3, is encoded as shown in Figure 8/Q.713. 3.4.2.3.4 Global title indicator = 0100 8 7 6 5 4 3 2 1 Translation type octet 1 Numbering plan Encoding scheme octet 2 Spa Nature of address indicator octet 3 re Address information octet 4 and further FIGURE 11/Q.713 Global title format for indicator 0100 The field "translation type" is as described in S 3.4.2.3.2. The fields "numbering plan" and "encoding scheme" are as described in S 3.4.2.3.3. The field Snature of address indicator" is as described in S 3.4.2.3.1. If the encoding scheme is binary coded decimal, the global title value, starting from octet 4, is encoded as shown in Figure 8/Q.713. 3.5 Calling party address The "calling party address" is a variable length parameter. Its structure is the same as the "called party address". When the calling party address is a mandatory parameter but is not available or must not be sent, the calling party address parameter only consists of the address indicator octet, where bits 1 to 7 are coded all zeros. 3.6 Protocol class The "protocol class" parameter field is a four bit field containing the protocol class. Bits 1-4 are coded as follows: 4321 0000 class 0 0001 class 1 0010 class 2 0011 class 3 When bits 1-4 are coded to indicate a connection-oriented-protocol class (class 2, class 3), bits 5-8 are spare. Fascicle VI.7 - Rec. Q.713 PAGE1 When bits 1-4 are coded to indicate a connectionless protocol class (class 0, class 1), bits 5-8 are used to specify message handling as follows: Bit 8 7 6 s 5 0 0 0 no special options 0 0 0 0  1 to  spare 0 1 1 θ 1 1 0 0 return message on error 0 1 0 0  1 to  spare 1 1 1 θ 1 3.7 Segmenting/reassembling The "segmenting/reassembling" parameter field is a one octet field and is structured as follows: 8 7 6 PAGE30 Fascicle VI.7 - Rec. Q.713 5 4 3 2 1 reserve M Bits 8-2 are spare. Bit 1 is used for the More Data indication and is coded as follows: 0 = no more data 1 = more data 3.8 Receive sequence number The "receive sequence number" parameter field is a one octet field and is structured as follows: 8 7 6 5 4 3 2 1 P(R) / Bits 8-2 contain the receive sequence number P(R) used to indicate the sequence number of the next expected message. P(R) is binary coded and bit 2 is the LSB. Bit 1 is spare. Fascicle VI.7 - Rec. Q.713 PAGE1 3.9 Sequencing/segmenting The sequencing/segmenting parameter field consists of two octets and is structured as follows: 8 7 6 5 4 3 2 1 octet 1 P(S) / octet 2 P(R) M Bits 8-2 of octet 1 are used for indicating the send sequence number P(S). P(S) is binary coded and bit 2 is the LSB. Bit 1 of octet 1 is spare. Bits 8-2 of octet 2 are used for indicating the receive sequence number P(R). P(R) is binary coded and bit 2 is the LSB. Bit 1 of octet 2 is used for the More Data indication and is coded as follows: 0 = no more data 1 = more data The sequencing/segmenting parameter field is used exclusively in protocol class 3. 3.10 Credit The "credit" parameter field is a one-octet field used in the protocol classes which include flow control functions. It contains the window size value coded in pure binary. 3.11 Release cause The release cause parameter field is a one-octet field containing the reason for the release of the connection. The coding of the release cause field is as follows: Bit 8 7 6 5 4 3 2 s 1 0 0 0 0 0 0 0 end user originated 0 0 0 0 0 0 0 0 end user congestion 1 PAGE30 Fascicle VI.7 - Rec. Q.713 0 0 0 0 0 0 1 end user failure 0 0 0 0 0 0 0 1 SCCP user originated 1 0 0 0 0 0 1 0 remote procedure error 0 0 0 0 0 0 1 0 inconsistent connection data 1 0 0 0 0 0 1 1 access failure 0 0 0 0 0 0 1 1 access congestion 1 0 0 0 0 1 0 0 subsystem failure 0 0 0 0 0 1 0 0 subsystem congestion8) 1 0 0 0 0 1 0 1 network failure 0 0 0 0 0 1 0 1 network congestion 1 0 0 0 0 1 1 0 expiration of reset timer 0 8) Subsystem congestion control procedure is for further study. Fascicle VI.7 - Rec. Q.713 PAGE1 0 0 0 0 1 1 0 expiration of receive inactivity timer 1 0 0 0 0 1 1 1 not obtainable 0 0 0 0 0 1 1 1 unqualified 1 0 0 0 1 0 0 0  0 to  spare 1 1 1 1 1 1 1 θ 1 Note - A more comprehensive list of causes covering X.96 call progress information is for further study. PAGE30 Fascicle VI.7 - Rec. Q.713 3.12 Return cause In the Unitdata Service message, the «return cause» parameter field is a one octet field containing the reason for message return. Bits 1-8 are coded as follows: Bit 8 7 6 5 4 3 2 s 1 0 0 0 0 0 0 0 no translation for an address of such nature 0 0 0 0 0 0 0 0 no translation for this specific address 1 0 0 0 0 0 0 1 subsystem congestion9) 0 0 0 0 0 0 0 1 subsystem failure 1 0 0 0 0 0 1 0 unequipped user 0 0 0 0 0 0 1 0 network failure 1 0 0 0 0 0 1 1 network congestion 0 0 0 0 0 0 1 1 unqualified 1 0 0 0 0 1 0 0  0 9) Subsystem congestion control procedure is for further study. Fascicle VI.7 - Rec. Q.713 PAGE1 to  spare 1 1 1 1 1 1 1 θ 1 3.13 Reset cause The "reset cause" parameter field is a one octet field containing the reason for the resetting of the connection. The coding of the reset cause field is as follows: Bit 8 7 6 5 4 3 2 s 1 0 0 0 0 0 0 0 end user originated 0 0 0 0 0 0 0 0 SCCP user originated 1 0 0 0 0 0 0 1 message out of order - incorrect P(S) 0 0 0 0 0 0 0 1 message out of order - incorrect P(R) 1 0 0 0 0 0 1 0 remote procedure error - message out of window 0 0 0 0 0 0 1 0 remote procedure error - incorrect P(S) after 1 (re)initialization 0 0 0 0 0 1 1 remote procedure error - general 0 0 0 0 0 0 1 1 PAGE30 Fascicle VI.7 - Rec. Q.713 1 remote end user operational 0 0 0 0 1 0 0 network operational 0 0 0 0 0 1 0 0 access operational 1 0 0 0 0 1 0 1 network congestion 0 0 0 0 0 1 0 1 not obtainable 1 0 0 0 0 1 1 0 unqualified 0 0 0 0 0 1 1 0  1 to  spare 1 1 1 1 1 1 1 θ 1 3.14 Error cause The "error cause" parameter field is a one octet field containing the indication of the exact protocol error. The coding of the error cause field is as follows: Bit 8 7 6 5 4 3 2 s 1 0 0 0 0 0 0 0 Fascicle VI.7 - Rec. Q.713 PAGE1 0 local reference number (LRN) mismatch - unassigned destination LRN 0 0 0 0 0 0 0 local reference number (LRN) mismatch - inconsistent source 1 LRN 0 0 0 0 0 0 1 point code mismatch10) 0 0 0 0 0 0 0 1 service class mismatch 1 0 0 0 0 0 1 0 unqualified 0 0 0 0 0 0 1 0  1 to  spare 1 1 1 1 1 1 1 θ 1 10) National option. PAGE30 Fascicle VI.7 - Rec. Q.713 3.15 Refusal cause The refusal cause parameter field is a one octet field containing the reason for the refusal of the connection. The coding of the refusal cause field is as follows: Bit 8 7 6 5 4 3 2 s 1 0 0 0 0 0 0 0 end user originated 0 0 0 0 0 0 0 0 end user congestion 1 0 0 0 0 0 0 1 end user failure 0 0 0 0 0 0 0 1 SCCP user originated 1 0 0 0 0 0 1 0 destination address unknown 0 0 0 0 0 0 1 0 destination inaccessible 1 0 0 0 0 0 1 1 network resource - QOS not available/non-transient 0 0 0 0 0 0 1 1 network resource - QOS not available/transient 1 0 0 0 0 1 0 0 access failure 0 Fascicle VI.7 - Rec. Q.713 PAGE1 0 0 0 0 1 0 0 access congestion 1 0 0 0 0 1 0 1 subsystem failure 0 0 0 0 0 1 0 1 subsystem congestion11) 1 0 0 0 0 1 1 0 expiration of the connection establishment timer 0 0 0 0 0 1 1 0 incompatible user data 1 0 0 0 0 1 1 1 not obtainable 0 0 0 0 0 1 1 1 unqualified 1 0 0 0 1 0 0 0  0 to  spare 1 1 1 1 1 1 1 θ 1 Note 1 - The inclusion of the routing failure causes as specified for the "return cause" parameter in Recommendation Q.713, S 3.12, is for further study. Note 2 - A more comprehensive list of causes covering CCITT Recommendation X.96 call progress information is for further study. 3.16 Data The "data" parameter field is a variable length field containing SCCP-user data to be transferred transparently between the SCCP user functions. 4 SCCP messages and codes 4.1 General 11) Subsystem congestion control procedure is for further study. PAGE30 Fascicle VI.7 - Rec. Q.713 4.1.1 In the following sections, the format and coding of the SCCP messages is specified. For each message a list of the relevant parameters is given in a tabular form. 4.1.2 For each parameter the table also includes: - a reference to the section where the formatting and coding of the parameter content is specified; - the type of the parameter. The following types are used in the tables: F = mandatory fixed length parameter; V = mandatory variable length parameter; O = optional parameter of fixed or variable length; - the length of the parameter. The value in the table includes: - for type F parameters the length, in octets, of the parameter content; - for type V parameters the length, in octets, of the length indicator and of the parameter content; (The minimum and the maximum length are indicated.) - for type O parameters the length, in octets, of the parameter name, length indicator and parameter content. (For variable length parameters the minimum and maximum length is indicated.) 4.1.3 For each message the number of pointers included is also specified. 4.1.4 For each message type, type F parameters and the pointers for the type V parameters must be sent in the order specified in the following tables. 4.2 Connection request (CR) The CR message contains: - the routing label, - 2 pointers, - the parameters indicated in Table 3/Q.713. 4.3 Connection confirm (CC) The CC message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 4/Q.713. 4.4 Connection refused (CREF) The message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 5/Q.713. 4.5 Released (RLSD) The RLSD message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 6/Q.713. 4.6 Release complete (RLC) The RLC message contains: - the routing label, - no pointers, - the parameters indicated in Table 7/Q.713. 4.7 Data form 1 (DT1) Fascicle VI.7 - Rec. Q.713 PAGE1 The DT1 message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 8/Q.713. 4.8 Data form 2 (DT2) The DT2 message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 9/Q.713. TABLE 3/Q.713 Message type: Connection request Parameter S Type (F V Length O) (octets) Message type code 2.1 F 1 Source local reference 3.3 F 3 Protocol class 3.6 F 1 Called party address 3.4 V 3 minimum Credit 3.10 O 3 PAGE30 Fascicle VI.7 - Rec. Q.713 Calling party address 3.5 O 4 minimum Data 3.16 O 3 - 130 End of optional parameters 3.1 O 1 TABLE 4/Q.713 Message type: Connection confirm Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Source local reference 3.3 F 3 Protocol class 3.6 F Fascicle VI.7 - Rec. Q.713 PAGE1 1 Credit 3.10 O 3 Called party address 3.4 O 4 minimum Data 3.16 O 3 - 130 End of optional parameter 3.1 O 1 TABLE 5/Q.713 Message type: Connection refused Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Refusal cause 3.15 PAGE30 Fascicle VI.7 - Rec. Q.713 F 1 Called party address 3.4 O 4 minimum Data 3.16 O 3 - 130 End of optional parameter 3.1 O 1 TABLE 6/Q.713 Message type: Released Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Source local reference 3.3 F 3 Release cause Fascicle VI.7 - Rec. Q.713 PAGE1 3.11 F 1 Data 3.16 O 3 - 130 End of optional parameter 3.1 O 1 PAGE30 Fascicle VI.7 - Rec. Q.713 TABLE 7/Q.713 Message type: Release complete Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Source local reference 3.3 F 3 TABLE 8/Q.713 Message type: Data form 1 Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Segmenting/reassembling Fascicle VI.7 - Rec. Q.713 PAGE1 3.7 F 1 Data 3.16 V 2 - 256 TABLE 9/Q.713 Message type: Data form 2 Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Sequencing/Segmenting 3.9 F 2 Data 3.16 V 2 - 256 PAGE30 Fascicle VI.7 - Rec. Q.713 4.9 Data acknowledgement (AK) The AK message contains: - the routing label, - no pointers, - the parameters indicated in Table 10/Q.713. TABLE 10/Q.713 Message type: Data acknowledgement Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Receive sequence number 3.8 F 1 Credit 3.10 F 1 4.10 Unitdata (UDT) The UDT message contains: - the routing label, - 3 pointers, - the parameters indicated in Table 11/Q.713. TABLE 11/Q.713 Message type: Unitdata Parameter Fascicle VI.7 - Rec. Q.713 PAGE1 S Type (F V Length O) (octets) Message type 2.1 F 1 Protocol class 3.6 F 1 Called party address 3.4 V 3 minimum Calling party address 3.5 V 2 minimum Data 3.16 V 2 - X a) a) Due to the ongoing studies on the SCCP called and calling party address, the maximum length of this parameter needs further study. It is also noted that the transfer of up to 255 octets of user data is allowed when the SCCP called and calling party address do not include global title. PAGE30 Fascicle VI.7 - Rec. Q.713 4.11 Unitdata service (UDTS) The UDTS message contains: - the routing label, - 3 pointers, - the parameters indicated in Table 12/Q.713. TABLE 12/Q.713 Message type: Unitdata service Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Return cause 3.12 F 1 Called party address 3.4 V 3 minimum Calling party address 3.5 V 2 minimum Data 3.16 V 2 - X a) a) See a) Table 11/Q.713. 4.12 Expedited data (ED) The ED message contains: - the routing label, Fascicle VI.7 - Rec. Q.713 PAGE1 - 1 pointer, - the parameters indicated in Table 13/Q.713. TABLE 13/Q.713 Message type: Expedited data Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Data 3.16 V 2 - 33 PAGE30 Fascicle VI.7 - Rec. Q.713 4.13 Expedited data acknowledgement (EA) The EA message contains: - the routing label, - no pointers, - the parameters indicated in Table 14/Q.713. TABLE 14/Q.713 Message type: Expedited data acknowledgement Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 4.14 Reset request (RSR) The RSR message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 15/Q.713. TABLE 15/Q.713 Message type: Reset request Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference Fascicle VI.7 - Rec. Q.713 PAGE1 3.2 F 3 Source local reference 3.3 F 3 Reset cause 3.13 F 1 PAGE30 Fascicle VI.7 - Rec. Q.713 4.15 Reset confirm (RSC) The RSC message contains: - the routing label, - no pointers, - the parameters indicated in Table 16/Q.713. TABLE 16/Q.713 Message type: Reset confirmation Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Source local reference 3.3 F 3 4.16 Protocol data unit error (ERR) The ERR message contains: - the routing label, - 1 pointer, - the parameters indicated in Table 17/Q.713. TABLE 17/Q.713 Message type: Protocol data unit error Parameter S Type (F V Length O) (octets) Message type Fascicle VI.7 - Rec. Q.713 PAGE1 2.1 F 1 Destination local reference 3.2 F 3 Error cause 3.14 F 1 PAGE30 Fascicle VI.7 - Rec. Q.713 4.17 Inactivity test (IT) The IT message contains: - the routing label, - no pointers, - the parameters indicated in Table 18/Q.713. TABLE 18/Q.713 Message type: Inactivity test Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 Destination local reference 3.2 F 3 Source local reference 3.3 F 3 Protocol class 3.6 F 1 Sequencing/segmenting a) 3.9 F 2 Credit a) 3.10 F Fascicle VI.7 - Rec. Q.713 PAGE1 1 a) Information in these parameter fields reflect those values sent in the last data Form 2 or Data acknowledgement message. They are ignored if the protocol class parameter indicates class 2. 5 SCCP Management messages and codes 5.1 General Management (SCMG) messages are carried using the connectionless service of the SCCP. When transferring SCMG messages, class 0 is requested with the "discard message on error" option. SCCP management message parts are provided in the "data" parameter of the Unitdata message. The Unitdata message contains: - the routing label, - 3 pointers, - the parameters indicated in Table 19/Q.713. Descriptions of the various parts are contained in the following sections. TABLE 19/Q.713 SCCP management message format Parameter S Type (F V Length O) (octets) Message type 2.1 F 1 (= Unitdata) Protocol class 3.6 F 1 (= Class 0, no return) Called party address 3.4 V 3 minimum (SSN = SCCP management) Calling party address 3.5 V 3 minimum a) (SSN = SCCP management) Data 3.16 V 6 (Data consists of an SCMG message with form as in Table 22/Q.713) PAGE30 Fascicle VI.7 - Rec. Q.713 a) SSN is always present. 5.1.1 SCMG format identifier The SCMG format identifier consists of a one-octet field, which is mandatory for all SCMG messages. The SCMG format identifier uniquely defines the function and format of each SCMG message. The allocation of SCMG format identifiers is shown in Table 20/Q.713. TABLE 20/Q.713 SCMG format identifiers Message Code 87654321 SSA Subsystem-Allowed 00000001 SSP Subsystem-Prohibited 00000010 SST Subsystem-Status-Test 00000011 SOR Subsystem-Out-of-Service-Request 00000100 SOG Subsystem-Out-of-Service-Grant 00000101 Fascicle VI.7 - Rec. Q.713 PAGE1 5.1.2 Formatting principles The formatting principles used for SCCP messages, as described in SS 1.3, 1.4, 1.5, 1.6, 2.2 and 2.3 apply to SCMG messages. 5.2 SCMG message parameters SCMG parameter name codes are given in Table 21/Q.713 with reference to the subsections in which they are described. Presently, these parameter name codes are not used since all SCMG messages contain mandatory fixed parameters only. TABLE 21/Q.713 SCMG parameter name codes Parameter name S Parameter name code 87654321 End of optional parameters 5.2.1 00000000 Affected SSN 5.2.2 00000001 Affected PC 5.2.3 00000010 Subsystem multiplicity indicator 5.2.4 00000011 5.2.1 End of optional parameters The "end of optional parameters" parameter field consists of a single octet containing all zeros. 5.2.2 Affected SSN The "affected subsystem number (SSN)" parameter field consists of one octet coded as directed for the called party address field, S 3.4.2.1. 5.2.3 Affected PC The "affected signalling point code (PC)" parameter field is represented by two octets which are coded as directed for the called party address field, S 3.4.2.2. 5.2.4 Subsystem multiplicity indicator The "subsystem multiplicity indicator" parameter field consists of one octet coded as shown in Figure 12/Q.713. 8 7 6 5 4 3 2 1 spare PAGE30 Fascicle VI.7 - Rec. Q.713 SMI FIGURE 12/Q.713 Subsystem multiplicity indicator format Fascicle VI.7 - Rec. Q.713 PAGE1 The coding of the SMI field is as follows: Bits 21 00 affected subsystem multiplicity unknown 01 affected subsystem is solitary 10 affected subsystem is duplicated 11 spare Bits 3-8 are spare. 5.3 SCMG messages Presently, all SCMG messages contain mandatory fixed parameters only. Each SCMG message contains: - 0 pointers - the parameters indicated in Table 22/Q.713. TABLE 22/Q.713 SCMG Message Parameter S Type (F V Length O) (octets) SCMG format identifier 5.1.1 F 1 (Message type code) Affected SSN 5.2.2 F 1 Affected PC 5.2.3 F 2 Subsystem multiplicity 5.2.4 F 1 indicator ANNEX A (to Recommendation Q.713) Mapping for cause parameter values A.1 Introduction During connection refusal/release/reset, the SCCP and its users could take necessary corrective actions, if any, only upon relevant information available to them. Thus, it would be very helpful if those information could be conveyed correctly. During connection release, the "release cause" parameter in the Released (RLSD) message and the N-DISCONNECT primitive (with parameters "originator" and "reason") are used together to convey those information on the initiator and the cause of the connection release. In addition, the N-DISCONNECT primitive is also used together with the "refusal cause" parameter in the Connection Refused (CREF) message to convey those information during connection refusal. During connection reset, the "reset cause" parameter in the Reset Request (RSR) message and the N-RESET primitive (with parameters "originator" and "reason") are used together similarly. In order to convey those information correctly, this Annex provides a guideline for the mapping of values between the cause parameters and the corresponding N-primitive parameters during various scenarios. PAGE30 Fascicle VI.7 - Rec. Q.713 A.2 Connection refusal Table A-1/Q.713 describes the mapping of values between the "refusal cause" parameter (S 3.15, Rec. Q.713) and the "originator", "reason" parameters in the N-DISCONNECT primitive (S 2.1.1.2.4, Rec. Q.711). A.3 Connection release Table A-2/Q.713 describes the mapping of values between the "release cause" parameter (S 3.11, Rec. Q.713) and the "originator", "reason" parameters in the N-DISCONNECT primitive (S 2.1.1.2.4, Rec. Q.711). A.4 Connection reset Table A-3/Q.713 describes the mapping of values between the "reset cause" parameter (S 3.13, Rec. Q.713) and the "originator", "reason" parameters in the N-RESET primitive (S 2.1.1.2.3, Rec. Q.711). TABLE A-1/Q.713 Mapping during connection refusal CREF Message N-DISCONNECT primitive Code Refusal cause Reason Originat or 00000000 end user originated connection refusal - end user NSU originated 00000001 end user congestion connection refusal - end user NSU congestion 00000010 end user failure connection refusal - end user NSU failure 00000011 SCCP user originated connection refusal - SCCP NSU user originated 00000100 destination address unknown connection refusal - NSP destination address unknown (non-transient condition) 00000101 destination inaccessible connection refusal - Fascicle VI.7 - Rec. Q.713 PAGE1 destination NSP inaccessible/transient condition 00000110 network resource - QOS connection refusal - QOS NSP a) unavailable/non-transient unavailable/non-transient condition 00000111 network resource - QOS connection refusal - QOS NSP a) unavailable/transient unavailable/transient condition 00001000 access failure connection refusal - access NSU failure 00001001 access congestion connection refusal - access NSU congestion 00001010 subsystem failure connection refusal - NSP destination inaccessible/non-transient condition 00001011 subsystem congestion connection refusal - NSU subsystem congestion 00001100 expiration of connection connection refusal - reason NSP a) estimated timer unspecified/transient 00001101 inconsistent user data connection refusal - PAGE30 Fascicle VI.7 - Rec. Q.713 incompatible information in NSU NSDU 00001110 not obtainable connection refusal - reason NSP a) unspecified/transient 00001110 not obtainable connection refusal - undefine undefined d 00001111 unqualified connection refusal - reason NSP a) unspecified/transient 00001111 unqualified connection refusal - undefine undefined d NSU Network Service User NSP Network Service Provider a) Only those cases will be applicable if the SCCP originates the refusal procedure in response to REQUEST interface element. TABLE A-2/Q.713 Mapping during connection release RLSD Message N-DISCONNECT primitive Code Release cause Reason Originat or 00000000 end user originated disconnection - normal NSU condition 00000001 end user congestion disconnection - end user Fascicle VI.7 - Rec. Q.713 PAGE1 congestion NSU 00000010 end user failure disconnection - end user NSU failure 00000011 SCCP user originated disconnection - SCCP user NSU originated 00000100 remote procedure error disconnection - abnormal NSP condition of transient nature 00000101 inconsistent connection data disconnection - abnormal NSP condition of transient nature 00000110 access failure disconnection - access NSU failure 00000111 access congestion disconnection - access NSU congestion 00001000 subsystem failure disconnection - abnormal NSP condition of non-transient nature 00001001 subsystem congestion disconnection - subsystem PAGE30 Fascicle VI.7 - Rec. Q.713 congestion NSU 00001010 network failure disconnection - abnormal NSP condition of non-transient nature 00001011 network congestion disconnection - abnormal NSP condition of transient nature 00001100 expiration of reset timer disconnection - abnormal NSP condition of transient nature 00001101 expiration of receive disconnection - abnormal NSP inactivity timer condition of transient nature 00001110 not obtainable a) disconnection - undefined NSP 00001110 not obtainable a) disconnection - undefined undefine d 00001111 unqualified disconnection - abnormal NSU condition 00001111 unqualified disconnection - undefined Fascicle VI.7 - Rec. Q.713 PAGE1 NSP 00001111 unqualified disconnection - undefined undefine d NSU Network Service User NSP Network Service Provider a) The need for this value is for further study. TABLE A-3/Q.713 Mapping during connection reset RSR Message N-RESET primitive Code Reset cause Reason Originat or 00000000 end user originated reset - user synchronization NSU 00000001 SCCP user originated reset - user synchronization NSU 00000010 message out of order - reset - unspecified NSP incorrect P(S) 00000011 message out of order - reset - unspecified NSP incorrect P(R) 00000100 remote procedure error - reset - unspecified NSP message out of window PAGE30 Fascicle VI.7 - Rec. Q.713 00000101 remote procedure error - reset - unspecified NSP incorrect P(S) after initialization 00000110 remote procedure error - reset - unspecified NSP general 00000111 remote end user operational reset - user synchronization NSU 00001000 network operational reset - unspecified NSP 00001001 access operational reset - user synchronization NSU 00001010 network congestion reset - network congestion NSP 00001011 not obtainable a) reset - unspecified NSP 00001011 not obtainable a) reset - undefined undefine d 00001100 Fascicle VI.7 - Rec. Q.713 PAGE1 unqualified reset - unspecified NSP 00001100 unqualified reset - undefined undefine d NSU Network Service User NSP Network Service Provider a) The need for this value is for further study. PAGE30 Fascicle VI.7 - Rec. Q.713