no.7(sccp&tcap&inap)
DESCRIPTION
SS7 protocolTRANSCRIPT
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HUAWEI CCS7 Signaling System
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HUAWEI
Chapter 1 SCCP Chapter 2 TCAP Chapter 3 INAP
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HUAWEI
SCCP: Signaling Connection Control Part
Chapter 1 SCCPChapter 1 SCCP
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HUAWEI Where is SCCP?
INAP: IN Application Protocol MAP: Mobile Application PartCAP: CAMEL Application Part TCAP: Transaction Capability Application PartTUP: Telephone User Part ISUP: ISDN User PartMTP: Message Transfer Part SCCP: Signaling Connection Control Part
TUP ISUP TCAP
INAP CAP MAP
MTP
SCCP
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HUAWEI What is SCCP?
In No.7 signaling system , SCCP and MTP layer three together are responsible for signaling network layer function. SCCP expends the MPT functions in the following points:
Enable to convey various non-circuit-related signaling message.
Provide enhanced addressing and routing function, and enable to achieve the direct global transmission between different CCS7 networks by using GT addressing.
Expend the user part of MTP. SCCP supports up to 256 kinds of sub systems in stead of 16 in MTP.
Enable to provide connectionless service and connection-oriented service.
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HUAWEI Service Functions of SCCP Network
According to the various service requirement needed by user, the SCCP provides four classes of service: two for connectionless services and two for connection-oriented services. The four classes are:
Class 0: Basic connectionless class.
Class 1: In-sequence delivery connectionless class.
Class 2: Basic connection-oriented class.
Class 3: Flow control connection-oriented class.
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HUAWEI Addressing and Routing Functions of SCCP
The SCCP routing provides a powerful address translation function, which requires for connectionless and connection-oriented service. The SCCP routing provides a powerful addressing information translation function on behalf of its users. The routing function also responds to the MTP and SCCP congestion reports.
Addressing within the SCCP of CCS7 makes use of three separate elements:
DPC;
Global Title (GT);
Sub-System Number (SSN);
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HUAWEI Primitive
In CCS7 system, the information exchange between two adjacent layers is called primitive which includes primitive name, primitive type and primitive parameters. There are four types of primitives:
Request Indication Response Confirmation
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HUAWEI Primitives between SCCP and SCCP-User
Primitives between SCCP and SCCP-User (TCAP) are N_Primitives. The connectionless services use the following N_Primitives:
N_UNITDATA_REQ : is used when SCCP-User requires SCCP to send data.
N_UNITDATA_IND : is used when SCCP reports the received data to SCCP-User.
N_NOTICE_IND : is used when SCCP reports the reason why the SCCP-User data cannot be sent to peer point.
N-Primitives can be traced on SSP maintenance terminal.
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HUAWEI N_UNITDATA Parameters
N-UNITDATA_IND and N-UNITDATA_REQ have the same parameters.
SCCP-USER Octet (83H)
Routing Label (DPC 、 OPC 、 SLS)
Sequence Control (SLS)
Protocol Class (81H)
Parameter Location Pointer (Called Address, Caller Address, User Data Pointer)
Called Address (Destination Address)
Caller Address (Source Address)
User Data (SCCP-User Data to be sent by SCCP transparently, SCCP makes no change to them)
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HUAWEI
N_NOTICE has the same parameter structure with N_UNITDATA, but the Protocol Class is changed to return reason.
N_NOTICE Parameters
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HUAWEI SCCP Message Types
Message is the information exchanged by the same layers in two signaling points.
There are 17 kinds of SCCP messages. Among them UDT (Unit Data) and UDTS (Unit Data Service) are used for connectionless services. The codes for UDT and UDTS are 09H and 0AH.
INAP only uses UDT messages
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HUAWEI
TCAP: Transaction Capability Application Part
Chapter 2 TCAPChapter 2 TCAP
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HUAWEI Applications of TCAP
Applications of TCAP:
Data Exchange between switching systems
Switching systems access network database center
Network databases establish remote operation dialogue
Examples of TCAP applications:
Mobile service applications
Free phone service (800-service)
Credit Card calling
Operation & Maintenance applications
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HUAWEI Dialogue
Dialogue is the association established between two TC -users exchanging data. Whenever two signaling points are going to exchange data, they will setup a dialogue via TCAP. It is TCAP that initiates, maintains and releases of a dialogue. But TCAP does not care the functions of the dialogue.
The procedure of message exchange between two signaling points is similar to man-machine dialogue mode, which involves all necessary messages such as BEGIN and END.
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HUAWEI Component
Component is the protocol data unit exchanged between TC –users. i.e. the information exchanged in a dialogue is just a set components.
Components are defined by TC-Users. Components include the invoke operation by initiator and the returned result of the operation. The operation is decided by applications, e.g. number translation.
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HUAWEI
A dialogue has one or more components. A service procedure is just one dialogue. i.e. all the operations of a service procedure buildup a dialogue, the dialogue is the carrier of the operations.
The Relationship Between Dialogue and Component
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HUAWEI Categories of TCAP Components
Invoke( INV) is used to send an operation request to remote TC-User.
Return Result-Last( RR-L) is used to return the components of final result of last INV operation.
Return Result-not Last( RR-NL) is used to return the components of non-final result of last INV operation.
Return Error( RE) is used to return the components of error information, in which an error code is embedded
Reject( RJ): is used to reject last INV operation, in which a problem code is embedded.
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HUAWEI
According to different requirements of operation results, TCAP are classified into 4 classes:
Class 1: Result will be returned no matter the operation is successful or not. i.e. a RR-L, RR-NL or RE must be returned.
Class 2: Only when the operation fails, a RE will be returned.
Class 3: Only when the operation succeeds, a RR-L or RR-NL will be returned.
Class 4: No result returned no matter the operation is successful or not.
Classes of TCAP Operations
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HUAWEI
TCAP and TC-User exchange data via TC_Primitives.
There are 16 kinds of TC_Primitives, among them there 9 Component TC-Primitives which are related to components and 7 Dialogue TC-Primitives which are related to dialogues.
The TC_Primitives from TCAP to TC-User are Indication primitives, from TC-User to TCAP are Request primitives.
TC Primitives
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HUAWEI Component TC_Primitives (1)
TC- INVOKE is used to invoke an operation.
TC- RESULT- L is used to return the result of an operation.
TC- RESULT- NL is similar to TC - RESULT - L, but only returns the middle result.
Note: all above primitives have both Indication and Request types.
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HUAWEI
TC- U- ERROR is a Request Primitive which is used to return the error code when the operation fails although TC-User has received the correct operation request.
TC- U- REJECT : is a Request Primitive which is used to return reject code when TC-User has received an incorrect operation request.
TC- U- CANCEL is a Request Primitive which is used for TC-User to request TCAP to cancel an operation.
Component TC_Primitives (2)
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HUAWEI
TC- L- CANEL is an Indication Primitive which is used to notify TC-User an operation is overtime.
TC- L- REJECT is an Indication Primitive which is used to reject an operation by local TCAP.
TC- R- REJECT : is an Indication Primitive which is used to reject an operation when remote TCAP rejects the operation.
Component TC_Primitives (3)
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HUAWEI Types of TCAP Dialogues
There are two types of TCAP dialogues.
Unstructured Dialogue in which only unidirectional (UNI) messages are included. No response to be returned from opposite point in unstructured dialogue (e.g. a dialogue for sending an alarm message). Intelligent Network seldom uses this kind of dialogues.
Structured Dialogue has initiating, maintaining and ending processes. It has BEGIN, CONTINUE and END or ABORT messages. Intelligent Network just uses this kind of dialogues.
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HUAWEI
TC-UNI TC-User or TCAP request to begin a UNI dialogue.
TC- BEGIN Request or indicate to begin a dialogue.
TC- CONTINUE Request or indicate to maintain a dialogue.
TC- END Request or indicate to end a dialogue.
Dialogue TC_Primitives (1)
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HUAWEI
TC- U- ABORT : Request to abort a dialogue.
TC- P- ABORT : Indicate TC-User to abort a dialogue because of the error in transaction layer.
TC- NOTICE : Indicate TC-User that the network service provider cannot provide the required service (e.g. STP does not support INAP).
Dialogue TC_Primitives (2)
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HUAWEI An Example of TCAP Process
TC-BeginTC-Invoke (Invoke)
TC-ContinueTC-Invoke (Invoke)
TC-Continue
TC-Result-L (RR-L)
TC-End
TC-Result-L (RR-L)
Node1 (SSP) Node2 (SCP)
SSP begins a dialogue to query the balance of a calling card subscriber.
SCP asks SSP to return the password.
SSP returns the password.
SCP returns balance of the subscriber.
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HUAWEI
INAP: Intelligent Network Application Part
Chapter 3 INAPChapter 3 INAP
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HUAWEI The Functions of INAP
INAP defines operation criterion among the IN functional entities SSF, SCF, SRF and SDF.
INAP is transmitted by SCCP UDT data, using connectionless services.
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HUAWEI The Relationship Between INAP and SCCP
INAP usually uses DPC+SSN routing mode of SCCP.
INAP can also use GT routing mode of SCCP.
INAP uses class 0 and class 1 connectionless services of SCCP.
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HUAWEI INAP Operation Categories
Class 1: Result will be returned no matter the operation is successful or not. i.e. a RR-L, RR-NL or RE must be returned.Class 2: Only when the operation fails, a RE will be returned.Class 3: Only when the operation succeeds, a RR-L or RR-NL will be returned.Class 4: No result returned no matter the operation is successful or not.
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HUAWEI
INAP is a kind of TC-User.
In INAP protocol, all INAP operations are also classified into 4 classes.
Class 1 Activate Service Filtering, P&C
Class 2 Initial DP, RRBE
Class 3 AT
Class 4 RC, BER
INAP Operations
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HUAWEI IDP: Initial DP
IDP is the first INAP message sent from SSP to SCP, requesting SCP to establish the control relationship for an IN call. The parameters included in IDP are: access code, service key (the unique identifier of an IN service), caller number, called number, number attributes, etc.
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HUAWEI RRBE: Request Report BCSM Event
RRBE is sent from SCP to SSP, requesting SSP to configure DP dynamically. When SSP meets these DPs in later call process, SSP will report call information to SCP. RRBE provides SCP the condition of controlling calls.The parameters of RRBE include DP type, DP condition, etc. One RRBE can configure several DPs.
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HUAWEI CTR: Connect To Resource
CTR is sent from SCP to SSP, requesting SSP to connect the user to IP. CTR provides the users the condition of using IP.If IP is integrated with SSP, SSP makes only the internal connection with IP. If IP is independent from SSP, SSP communicates IP via TUP messages, connecting the users to IP through PSTN voice channels.
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HUAWEIP&C: Prompt & Collect User Information
P&C is sent from SCP to SSP, requesting IP to play voice prompts the users and collect the users’ input.
P&C needs IP to return operation results.
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HUAWEI DFC: Disconnect Forward Connect
DFC is sent from SCP to SSP, requesting SSP to disconnect the connection between the users and IP.
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HUAWEI AC: Apply Charging
AC is sent from SCP to SSP, requesting SSP to charge the call.
The parameters of AC include: charge class, the balance of the subscriber, charging party, etc.
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HUAWEIConnect:
Connect is sent from SCP to SSP, requesting SSP to connect the users to the designated number.
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HUAWEI ACR: Apply Charging Report
ACR is sent from SSP to SCP, reporting the charge result.The parameters in ACR include: the call start time, call end time, call length, caller number, called number, charging number, fee, etc.
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HUAWEI ERB: Event Report BCSM
ERB is sent from SSP to SCP when SSP detects the DPs configured by SCP in last RRBE message, reporting the call information to SCP.
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HUAWEI RC: Release Call
RC is sent from SCP to SSP, requesting SSP to release the occupied IN call resources.
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HUAWEIPA: Play announcement
PA is sent from SCP to SSP, requesting IP to play voice prompts to the users.
PA does not need result return from IP.
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HUAWEI SRR: Specialized Resource Report
SRR is sent from SSP to SCP, notifying SCP the end of playing announcement.
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HUAWEI AT: Activity Test
SCP sends AT to SSP every 6 minutes when the call is established to check the communication between SSP and SCP. If SSP can return AT_ack, the communication is good. If no AT_ack returns to SCP, the communication is broken, and SCP will release the resources occupied this IN call.
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HUAWEI
Initial DPRequest Report BCSM Event
Apply Charging
Apply Charging ReportBCSM Event ReportRelease Call
Connect
SSP SCP
An Example of INAP (FPH Service)
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HUAWEI An Example of INAP (Continue)
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HUAWEI SCCP 、 TCAP and INAP (FPH Service)
AP: Application Process, which processes IN calls in SSP.
InitialDP
Request Report Bcsm Event
Apply Charging
Connect
Apply Charging Report
Event Report BCSM
Release Call
AP
TC-BEGIN-REQ
TC-INVOKE-REQ
TC-CONTINUE-IND
TC-INVOKE-IND
TC-CONTINUE-IND
TC-INVOKE-IND
TC-CONTINUE-IND
TC-INVOKE-IND
TC-CONTINUE-REQ
TC-INVOKE-REQ
TC-CONTINUE-REQ
TC-INVOKE-REQ
TC-END-IND
TC-INVOKE-IND
TCAP
N_UNITDATA-REQ
N_UNITDATA-IND
N_UNITDATA-IND
N_UNITDATA-IND
N_UNITDATA-REQ
N_UNITDATA-REQ
N_UNITDATA-IND
UDT
UDT
UDT
UDT
UDT
UDT
UDT
MSU
MSU
MSU
MSU
MSU
MSU
MSU
SCCP MTP SCPINAP