gsm A接口信令分析.docx

1、gsm A接口信令分析Appendix A:SCCP Message Format and CodeSCCP MessagesGeneral layout of SCCP message is as follows:SCCP UDT Message StructureSCCP UDTS Message StructureSCCP Parameter Name CodesSCCP Message TypeMessage TypeProtocol ClassCode0123CR Connection RequestXXConnection Oriented Message0000 0001CC C

2、onnection ConfirmXXConnection Oriented Message0000 0010CREF Connection RefusedXXConnection Oriented Message0000 0011RLSD ReleasedXXConnection Oriented Message0000 0100RLC Release CompleteXXConnection Oriented Message0000 0101DT 1 Data Form 1XConnection Oriented Message0000 0110DT 2 Data Form 2XConne

3、ction Oriented Message0000 0111AK Data AcknowledgmentXConnection Oriented Message0000 1000UDT UnidataXXConnectionless Message0000 1001UDTS Unidata ServiceXXConnectionless Message0000 1010ED Expedited DataXConnection Oriented Message0000 1011EA Expedited Data AcknowledgmentXConnection Oriented Messag

4、e0000 1100RSR Reset RequestXConnection Oriented Message0000 1101RSC Reset ConfirmationXConnection Oriented Message0000 1110ERR ErrorXXConnection Oriented Message0000 1111IT Inactivity TestXXConnection Oriented Message0001 0000The following SCCP messages are used frequently: Connect Request (CR) Conn

5、ect Confirm (CC) Connection Refused (CREF) Data Form1 (DT1) (This message carries DTAP & BSSMAP messages) Released (RLSD) Release Complete (RLC) Unit Data (UDT) (This message carries BSSMAP & MAP messages)SCCP Protocol Class ParametersOptionMessage HandlingProtocol Class1 Byte0000Bits 4321Protocol C

6、lassBits 8765Message Handlingno special options0000class 00001class 1spareto0001class 2011100100011class 3return message on error100011111001tospareSCCP DiagnosticsBits 8 thru 1Diagnostics00000000no translation for address of such nature00000010subsystem congestionno translation for this specific ad

7、dress0000000100000011subsystem failureunequipped user0000010000000101tospare11111111Calling Party and Called Party AddressThe CgPA and the CdPA are composed of some combination of the following: address indicator (mandatory) point code (optional) subsystem number (optional) global title (optional)Ad

8、dress IndicatorThe address indicator, identifies which optional fields are present and includes the Routing Indicator (RI). The RI determines whether routing is based on point code and subsystem number or global title.The CgPA/CdPA address indicator bits are defined as follows for CCITT:Note: Global

9、 Title is not supported by GSM specification, according to SS7 Based A-Interface IS-651.SCCP Signaling Point CodeA Point Code identifies a specific signaling point within a CCS7 network. As shown below, the signaling point code is represented by two octets in CCITT.8 7 6 5 4 3 2 11 Octet1 Octet00Are

10、a NetworkZoneSig. pointSCCP Subsystem NumberMAPLIDBQ00100011INAPBSSAP1111111000001100AUC00001010EIR00001001MSC00001000VLRHLRMAPOMAP00000111000001100000010100000100000000110000001000000001SSN not known/not used00000000Bits 8 thru 1SCCP managementISDN user partSpareSCCP Global Title FieldGlobal Title

11、Indicator = 00018 7 6 5 4 3 2 1Signaling Point Code2 OctetsSubsystem Number1 Octet0 = Even number of address signal1 = Odd number of address signalGlobal TitleVariableNature of addressingindicatorBits76543218 7 6 5 4 3 2 10000000SpareNature of addressingindicator1 octetO/E0000001User NumberAddress I

12、nformationn octets0000010Spare nationalNational valid numberInternational Number000010000000118 7 6 5 4 3 2 1Octet 21st Address Signal2nd Address SignalOctet mOctet 3nth Address SignalFiller (if necessary)3rd Address Signal4th Address SignalGlobal Title Indicator = 00108 7 6 5 4 3 2 1Signaling Point

13、 Code2 OctetsSubsystem Number1 OctetGlobal TitleVariable8 7 6 5 4 3 2 1Translation Type1 octetn octetsAddress InformationTranslation Type is under research. In GSM it is all 0s.Global Title Indicator = 00118 7 6 5 4 3 2 1Signaling Point Code2 OctetsSubsystem Number1 OctetVariableGlobal Title8 7 6 5

14、4 3 2 11 octetTranslation TypeNumbering Plan Scheme1 octetEncodingn octetsAddress InformationSpareSpareBCD, Even number of digitsBCD, Odd number of digitsunknown1111to111000110010000100004321Encoding SchemeBits Global Title Indicator = 0100sparen octetsAddress InformationEncodingNumbering Plan Schem

15、e1 octetTranslation Type1 octetNature of addressing indicator1 octetGlobal TitleSubsystem NumberSignaling Point CodeVariable1 Octet2 Octets8 7 6 5 4 3 2 18 7 6 5 4 3 2 18765Bits ISDN/ Mobile Numbering Plan(E.214)Land Mobile Numbering Plan (E.212)Maritime Mobile Numbering Plan(E.210&E.211)Telex Numbe

16、ring Plan (F.69)Data Numbering Plan (X.121)ISDN Numbering Plan (E.163/E.164)unknownNumbering Plan Scheme00000001Spare001000110100010101100111Connection Request (CR) MessageThis message is sent by the calling SCCP to request the setup of a signaling connection to the called SCCP.CR Message FormatSCCP

17、 Signaling InformationFieldSize (octets)MTMessage Type (#01)1Mandatory FixedSource Local Reference3Protocol class1Mandatory VariablePointer to CdPA1Pointer to optional part1Called Party Address (CdPA)3 min.Optional ParametersCredit3Calling Party Address (CgPA)4 min.Data3-130SCCP hop counter3End of o

18、ptional parameters1Note: Credit field is not used.Protocol class 3 is not supported.SCCP hop counter accepted but is not used.SCCP hop counter is never sent.Connection Confirm (CC) MessageThis message confirms to the calling SCCP that the called SCCP has performed the setup of the signaling connecti

19、on.CC Message FormatSCCP Signaling InformationFieldSize (octets)MTMessage Type (#02)1Mandatory FixedDestination Local Reference3Source Local Reference3Protocol class1Optional ParametersCredit3Called Party Address (CdPA)4 min.Data3-130End of optional parameters1Note: Credit field is not used.Protocol

20、 class 3 is not supported.Connection Refused (CREF) MessageThis message is sent by the called SCCP to indicate that the called SCCP has refused to setup the signaling connection.CREF Message FormatSCCP Signaling InformationFieldSize (octets)MTMessage Type (#03)1Mandatory FixedDestination Local Refer

21、ence3Refusal cause1Optional ParametersCalled Party Address (CdPA)4 min.Data3-130End of optional parameters1Note: Protocol class 3 is not supported.Refusal Cause:refusal cause is not used refusal cause is used 00000011 SCCP user originated- Timeout messages of the connection establishment timer conne

22、ction refusal, when CgPA is not valid.00000100 Destination address unknown- This procedure is used to return a CREF message to the far end whenever a CR message has arrived and the subsystem is incorrect or the subsystem in unavailable which results in a a local routing failure.00001100 expiration o

23、f the connection establishment timer- To user, in connection refusal indication if a timeout message of the connection establishment timer.00001110 not obtainable- To user, in connection refusal indication in connection_request_primitive.00001111 unqualified- when we cannot handle the connection req

24、uest then we send connection refused unqualified message.Data Form 1 (DT1) MessageThis message is sent by either end of a signaling connection to pass transparently SCCP user data between two SCCP nodes. The connection must already be established.DT1 Message FormatSCCP Signaling InformationFieldSize

25、 (octets)MTMessage Type (#06)1Mandatory FixedDestination Local Reference3Segmenting/reassembling1Mandatory VariablePointer to data1Data2-256bits218 Segmenting/reassemblingMBit 2 - 8: spareBit 1: M=0 No more data M=1 more dataReleased (RLSD) MessageThis message is sent in the forward or backward dire

26、ction, to indicate that the sending SCCP wants to release the signaling connection and the associated resources at the sending SCCP have been brought into the disconnect pending condition. It also indicates that the receiving node should release the connection and any other resources associated with

27、 it.RLSD Message FormatSCCP Signaling InformationFieldSize (octets)MTMessage Type (#04)1Mandatory FixedDestination Local Reference3Source Local Reference3Release Cause1Optional parametersData3-130End of optional parameters1Note: Protocol class 3 is not supported.Release Cause:release cause is used 0

28、0000000 End user originated- In RLSD message when CC message received and local user had requested for connection takedown after CR but before the CC received.- To user, if RLSD message received in disconnection indication in response to CR message.- To user, if RLSD message in disconnect indication

29、 received for an active connection.- To user, in disconnect indication, if error message received for an active state.- To far end in RLSD message, if error received for an active state.- In RLSD message, if local to disconnect active connection.- To user if response to CR is not CC, RLSD, CREF.00000010 End user failure- To user if inconsistent data received in CC message.00000101 inconsistent connection dat