01-2 Signaling Trace Guide

M900/M1800 Base Station Subsystem Signaling Analysis Manual Contents

Issue 06 (2006-08-20) Huawei Technologies Proprietary i

Contents

2 Signaling Trace Guide ..............................................................................................................2-1 2.1 Overview.......................................................................................................................................................2-2 2.2 Um Interface Trace........................................................................................................................................2-2

2.2.1 Functions..............................................................................................................................................2-2 2.2.2 Operations............................................................................................................................................2-3 2.2.3 Options.................................................................................................................................................2-5 2.2.4 Examples..............................................................................................................................................2-5

2.3 Abis Interface Trace ......................................................................................................................................2-6 2.3.1 Functions..............................................................................................................................................2-6 2.3.2 Operations............................................................................................................................................2-6 2.3.3 Options.................................................................................................................................................2-9 2.3.4 Examples............................................................................................................................................2-10

2.4 A Interface Trace .........................................................................................................................................2-11 2.4.1 Functions............................................................................................................................................2-11 2.4.2 Operations..........................................................................................................................................2-12 2.4.3 Options...............................................................................................................................................2-17 2.4.4 Examples............................................................................................................................................2-18

2.5 SS7 Trace ....................................................................................................................................................2-19 2.5.1 Functions............................................................................................................................................2-19 2.5.2 Operation and Options .......................................................................................................................2-21 2.5.3 Examples............................................................................................................................................2-25

2.6 SCCP Signaling Trace .................................................................................................................................2-27 2.6.1 Functions............................................................................................................................................2-27 2.6.2 Operations..........................................................................................................................................2-27 2.6.3 Options...............................................................................................................................................2-30 2.6.4 Examples............................................................................................................................................2-31

Figures M900/M1800 Base Station Subsystem

Signaling Analysis Manual

ii Huawei Technologies Proprietary Issue 06 (2006-08-20)

Figures

Figure 2-1 GSM protocol stack ..........................................................................................................................2-2

Figure 2-2 GSM interface trace..........................................................................................................................2-3

Figure 2-3 Um interface trace.............................................................................................................................2-4

Figure 2-4 Um interface trace message ..............................................................................................................2-4

Figure 2-5 GSM interface tracing review...........................................................................................................2-5

Figure 2-6 GSM interface trace..........................................................................................................................2-6

Figure 2-7 Abis interface trace ...........................................................................................................................2-7

Figure 2-8 Abis interface trace messages ...........................................................................................................2-8

Figure 2-9 GSM interface tracing review...........................................................................................................2-9

Figure 2-10 Abis interface messages ................................................................................................................2-10

Figure 2-11 GSM interface trace ......................................................................................................................2-12

Figure 2-12 Interface trace message filter parameter selection ........................................................................2-13

Figure 2-13 A interface trace message..............................................................................................................2-14

Figure 2-14 Details of A interface trace message .............................................................................................2-15

Figure 2-15 A interface trace message saving ..................................................................................................2-16

Figure 2-16 Input the file name to save the A interface message .....................................................................2-16

Figure 2-17 A interface tracing review.............................................................................................................2-17

Figure 2-18 Details of the PAGING message over the A interface ..................................................................2-18

Figure 2-19 Architecture of SS7.......................................................................................................................2-19

Figure 2-20 SS7 message trace.........................................................................................................................2-21

Figure 2-21 Setting for SS7 message tracing ...................................................................................................2-22

Figure 2-22 SS7 trace window .........................................................................................................................2-23

Figure 2-23 SS7 message tracing window .......................................................................................................2-25

Figure 2-24 SCCP maintenance window..........................................................................................................2-27

Figure 2-25 SCCP message trace .....................................................................................................................2-28

Figure 2-26 SCCP DPC message trace.............................................................................................................2-29

M900/M1800 Base Station Subsystem Signaling Analysis Manual Figures

Issue 06 (2006-08-20) Huawei Technologies Proprietary iii



Tables M900/M1800 Base Station Subsystem


iv Huawei Technologies Proprietary Issue 06 (2006-08-20)

Tables

Table 2-1 Submenus under the menu item [SS7 Message Trace] .....................................................................2-21

Table 2-2 Meanings of message types ..............................................................................................................2-22

Table 2-3 Meanings of filters............................................................................................................................2-23

M900/M1800 Base Station Subsystem Signaling Analysis Manual 2 Signaling Trace Guide

Issue 06 (2006-08-20) Huawei Technologies Proprietary 2-1

2 Signaling Trace Guide About This Chapter

The following table lists the contents of this chapter.

Title Description

2.1 Overview Introduces the interface trace functions of the BSS.

2.2 Um Interface Trace Describes the Um interface trace functions and how to trace the messages on the Um interface.

2.3 Abis Interface Trace Describes the Abis interface trace functions and how to trace the messages on the Abis interface.

2.4 A Interface Trace Describes the A interface trace functions and how to trace the messages on the A interface.

2.5 SS7 Trace Describes the SS7 trace functions and how to trace SS7 messages.

2.6 SCCP Signaling Trace Describes the SCCP signaling trace functions and how to trace SCCP messages.

2 Signaling Trace Guide M900/M1800 Base Station Subsystem


2-2 Huawei Technologies Proprietary Issue 06 (2006-08-20)

2.1 Overview Figure 2-1 shows the GSM protocol stack.

Figure 2-1 GSM protocol stack

CM

MM

RR

LAPDm

Sign. Layer1

L3

L2

L1

BTSM

MS

Um

SCCP

MTP

BTSM

RR BSSMAP

Abis

BTS

BSC

MSC

A

BSC

Sign. Layer1

Sign. Layer1

Sign. Layer1

RR

LAPDLAPDm LAPD

CM

MM

BSSMAP

SCCP

MTP

MS: Mobile station BTS: Base Transceiver Station BSC: Base Station Controller MSC: Mobile Switching Center CM: Connection Management MM: Mobility Management RR: Radio Resource management MTP: Message Transfer Part SCCP: Signaling Connection Control Part LAPD: Link Access Protocol on the D channel LAPDm: Link Access Protocol on the Dm channel BSSMAP: Base Station System Management Application Part BTSM: BTS Management

The interfaces of BSS include the A interface between BSC and MSC, the Um interface between BTS and MS, and the Abis interface between BSC and BTS.

The Base Station System (BSS) of Huawei provides powerful interface trace functions. During equipment interconnection (like the interconnection between the BSC of Huawei and MSC of another company) and equipment maintenance (such as frequent call drop, low handover success rate, MS access-to-network failure, and poor speech), these functions can be used to analyze the signaling procedure online, and locate the faults promptly.

BSS interface trace functions include Um interface trace, A interface trace, Abis interface trace, SS7 interface trace and SCCP trace.

2.2 Um Interface Trace 2.2.1 Functions

Um interface trace function is to trace the signaling over the radio interface of the cell in the BSC Maintenance System. In actual application, the Um interface is traced by the test MS and software. The Um interface trace in the maintenance system is not applied that frequently, and will be briefly described in this chapter.



2.2.2 Operations Step 1 Start the BSC Maintenance System, select the menu item [Trace/GSM Tracing/GSM Interface

Tracing], and an interface will pop up, as shown in Figure 2-2.

Figure 2-2 GSM interface trace




Step 2 Select the Um interface trace, module No., click , and an interface will pop up, as shown in Figure 2-3.

Figure 2-3 Um interface trace

Step 3 Input the cell number, TRX number and channel number, and the traced messages over the Um interface will be listed, as shown in Figure 2-4.

Figure 2-4 Um interface trace message



Step 4 Query saved messages through GSM Tracing Review

The messages traced and saved (note: they can be queried from other maintenance consoles only when the file header is modified with some edit tools) can be queried by selecting [Trace/GSM Tracing/GSM Tracing Review] in the BSC Maintenance System. Select the message file to be queried in the pop-up window, and click ; or copy the saved GMT files to another terminal, and query them through OMC LocalWS.

Figure 2-5 GSM interface tracing review

----End

2.2.3 Options z Cell Number: Number of the cell with the Um interface to be traced, decimal. z TRX Number: TRX number to be traced, decimal. z Channel Number: In use. z RR management procedure: Select the item, and the messages of this type will be listed

in the message trace window, like system information. z Mobility Management (MM) procedure: Displaying MM related messages, like

messages in TMSI reallocation procedure, authentication procedure and identification procedure.

z Call Control (CC) and call related Supplementary Service (SS) procedure: Displaying the messages related to call procedure and SS.

z Call-unrelated SS procedure: Such as REGISTER message that is call-unrelated supplementary service message.

z Short Message procedure: Short message related signaling procedures displayed in the trace window.

2.2.4 Examples The Um interface trace in the maintenance system is hardly applied, No example is provided.




2.3 Abis Interface Trace 2.3.1 Functions

In actual deployment and maintenance process, such faults as call drop, handover failure, MS access-to-network failure and poor quality of speech frequently occur. In these cases, it is necessary to locate the faults through signaling procedure analysis. Therefore, Abis interface trace is an important approach to locate problems in the field.

2.3.2 Operations Step 1 Start the BSC Maintenance System, select the menu item [Trace/GSM Trace/GSM Interface

Trace], and an interface will pop up, as shown in Figure 2-6.




Step 2 Select the module No. and Abis interface, and the interface will pop up, as shown in Figure 2-7.

Figure 2-7 Abis interface trace




Step 3 Select the Cell Number, TRX Number, click , and the traced messages over the Abis interface will pop up, as shown in Figure 2-8.

Figure 2-8 Abis interface trace messages

Step 4 Query saved messages through GSM Tracing Review

The messages traced and saved (note: they can be queried from other maintenance consoles only when the file header is modified with some edit tools) can be queried by selecting [Trace/GSM Tracing/GSM Tracing Review] in the BSC Maintenance System. Select the message file to be queried in the pop-up window, and click ; or copy the saved GMT files to another terminal, and query them through OMC LocalWS.



Figure 2-9 GSM interface tracing review

----End

2.3.3 Options Cell Number: Number of the cell whose Abis interface is to be traced, decimal.

TRX Number: TRX Number of the Abis interface to be traced, decimal; if it is not selected, the Abis signaling of the entire cell will be traced.

Channel Number: In use.

Measurement report: Select [Test Report], and the measurement report messages will be listed in the trace message window.

Radio link layer management procedures: Select [Radio Link Layer Management Message], the messages of this type will be listed in the trace window. They include: Link establishment indication (EST IND), link establishment request (EST REQ and EST CONF), link release indication, (REL IND), link release request (REL REQ and REL CONF), transmission of a transparent L3-Message in acknowledged mode (DATA REQ), reception of a transparent L3-Message in acknowledged mode (DATA IND), transmission of a transparent L3-Message in unacknowledged mode (UNIT DATA REQ), reception of a transparent L3-Message in unacknowledged mode (UNIT DATA IND), and link error indication (ERROR IND).

Dedicated channel management procedures: Channel activation (CHAN ACTIV and CHAN ACTIV ACK/NACK), channel mode modify (MODE MODIFY and MODE MODIFY ACK/NACK), handover detection (HANDO DET), start of encryption (ENCR CMD), deactivate SACCH (DEACT SACCH), radio channel release (RF CHAN REL and RF CHAN REL ACK), MS power control (MS POWER CONTROL), transmission power control (BS POWER CONTROL), connection failure (CONN FAIL IND), physical context request (PHYS CONTEXT REQ, PHYS CONTEXT CONF) and SACCH information modify (SACCH INFO MODIFY).

Common channel management procedures: channel request by MS (CHAN REQ), paging (PAG CMD), deletion indication (DELETE IND), CCCH load indication (CCCH LOAD




IND), broadcast information modify (BCCH INFO), short message cell broadcast (SMS BROADCAST REQ, CBCH LOAD IND and SMS BROADCAST CMD), and immediate assignment (IMM ASS CMD).

TRX management procedures: radio resource indication (RF RES IND), SACCH filling information modify (SACCH FILL), flow control (OVERLOAD), and error reporting (ERROR REPORT).

2.3.4 Examples Figure 2-10 illustrates a complete Abis interface message procedure.

Figure 2-10 Abis interface messages

Double click an Abis interface message in the maintenance system, and the type and the detailed description of this message will be listed.

A complete call procedure will be given based on the messages above:

Step 1 CHAN_RQD: This message is sent from MS to BTS to request for channel. Then, BTS transfers it to BSC. Key field in the message: Access Delay (2 bytes), indicating the access location of MS (from the BTS).

Step 2 CHAN_ACTIV: Sent back to BTS from BSC. Key fields: Timing Advance (2 byte), MS Power (2 bytes) and BS Power (2 bytes).

Step 3 CHAN_ACTIV_ACK: It is sent from BTS to BSC. No special point in it is to be concerned.

Step 4 IMMEDIATE_ASSIGN_COMMAND: It is used for BSC to assign SDCCH to MS. Key fields: Timing Advance.



Step 5 EST_IND: It is sent from BTS to BSC. Double click on the message, and the detailed information about it will be displayed: Key fields: Message Type (like CM Service Request), type of the message; Identity digit (TMSI allocated to this domain), and the encryption domain.

Step 6 DATA_REQ: Transparent L3-Message, generally including authentication request and classmark request messages.

Step 7 DATA_IND: Authentication response, classmark response and SETUP messages (with called number provided). Key field: SETUP message.

Step 8 MEAS_RES: Measurement reporting message, including SDCCH and TCH measurement messages. The detailed content including:

z Channel TYPE: SDCCH or TCH. z Time Slot Number: Timeslot No. z Uplink measurement: Uplink measurement report, including uplink Rx quality and Rx

level. z RXLEV_FULL_UP: When the uplink does not use DTX, the uplink Rx level is the value

of this domain. z RXLEV_SUB_UP: When the uplink uses DTX, the uplink Rx level is the value of this

domain. z RXQUAL_FULL_UP: When the uplink does not use DTX, the uplink Rx quality is the

value of this domain. z RXQUAL_SUB_UP: When the uplink uses DTX, the uplink Rx quality is the value of

this domain. z BS POWER: Transmit power of the BTS. z Actual Timing Advance: Timing advance. z L3 information: Downlink measurement values of the service area and its 6 neighbor

cells reported.

----End

2.4 A Interface Trace 2.4.1 Functions

In actual deployment and maintenance process, such faults as the interconnection coordination between the BSC of Huawei and MSC of another manufacturer via the A interface, A interface related MS access-to-network failure, assignment failure, call drop, handover failure, and poor quality of speech frequently occur. In these cases, it is necessary to locate the faults through the trace and analysis of the A interface signaling procedure.




2.4.2 Operations

Message trace Start the BSC Maintenance System, select [Trace/GSM Trace/GSM Interface Trace], and an interface will pop up, as shown in Figure 2-11.




Select A Interface and the corresponding module No., click , and an interface will pop up, as shown in Figure 2-12.

Figure 2-12 Interface trace message filter parameter selection




Generally, select Connectionless Message, DTAP Message and BSSMAP without the input of SCCP No, click , and a traced message over the A interface will pop up, as shown in Figure 2-13.

Figure 2-13 A interface trace message



Message view Select the message to be viewed in the Trace Message window, double click and the details of the message will be listed, as shown in Figure 2-14.

Figure 2-14 Details of A interface trace message




Message saving The A interface messages traced can be saved in the Operations and Maintenance terminal. Right click in the message trace window, and a menu will pop up, as shown in Figure 2-15.

Figure 2-15 A interface trace message saving

Select [Save] in the shortcut menu, and an interface will pop up, as shown in Figure 2-16.

Figure 2-16 Input the file name to save the A interface message



Enter the file name in the dialog box and click , and then the A traced interface messages will be saved under the directory "C: \OMC\Shell\XXX\trace" on the Operations and Maintenance terminal. Here, XXX is the name of BSC version No., for example, G3BSC32.10100.04.1120A. The suffix of the file name is "GMT".

View saved messages through GSM Tracing Review The saved messages can be viewed by clicking [Trace/GSM Tracing/GSM Tracing Review]. Select the message file to be view and click , as shown in Figure 2-17.

Figure 2-17 A interface tracing review

2.4.3 Options Connectionless messages: Paging and circuit management messages.

DTAP messages: Transparently transmitted messages in the CC layer and MM layer.

BSSMAP: A interface messages specified under the GSM 0808 protocol.

SCCP No.: connection No. of SCCP in the connection message, generally not required.




2.4.4 Examples Figure 2-18 illustrates a complete A interface PAGING message.

Figure 2-18 Details of the PAGING message over the A interface

Step 1 Displayed in SCCP Message Type. It is a N_UNIDATA_INDICATION message.

Step 2 Displayed in the BSSMAP Message Type, it is a PAGING message.

Step 3 The paging IMSI included in the IMSI code of this message is 460005050907827.



Step 4 The location area code of the paging message displayed in LAC is 8506 (hexadecimal).

----End

2.5 SS7 Trace 2.5.1 Functions

SS7 is divided into different modules based on its functions. Each module completes relatively independent functions, and transmits service information and network management information through primitives. The architecture is shown in Figure 2-19

Figure 2-19 Architecture of SS7

SCCP

OMAP

TCAP

MTP

ISUP TUP(1)

(3)(3)

(2) (2)

(3)

(1) TC-primitive (2) network service primitive (3)MPT service primitive

The function of each part in this architecture is briefly described as follows:

Step 1 Message Transfer Part (MTP), including 3 functional levels: signaling data link (physical layer, MTP L1), signaling link function (link layer, MTP L2), and signaling network function (network layer, MTP L3).

Step 2 Signaling Connection Control Part (SCCP): Enforcing the function of the MTP part, and providing the function equal to the OSI network layer.

Step 3 Telephone User Part (TUP): Stipulating call establishment and release related functions and programs, and supporting some SS.

Step 4 ISDN User Part (ISUP): Providing functions for speech and non-speech switching in ISDN, so as to support basic bearer services and SS.

Step 5 Transaction Capability Application Part (TCAP): Providing a group of procedures and functions for the communications of a series of application services.

Step 6 Operation and Maintenance Application Part (OMAP): Providing such functions as SS7 monitoring, measurement and management, as well as protocol test and monitoring online.

----End




The architecture of SS7 is described through primitives as follows:

MTP service primitives MTP_TRANSFER request: Used for SCCP to transfer signals and messages to MTP.

MTP_TRANSFER indication: Used for MTP to transfer signals and messages to SCCP.

MTP_PAUSE indication: Used for MTP to notify TUP that it cannot transfer the message to the destination.

MTP_RESUME indication: Used for MTP to notify TUP that it is capable to provide MTP services to the destination.

MTP_STATUS indication: Used for MTP to notify TUP that it can partially (congestion) provide MPT services to the destination. It is also used to notify MS the cause whether the remote MS is available or not.

MTP_RESTART indication: Upon the completion of MTP restart, it informs the local MTP users of the end of the MTP restart, and indicates whether a signaling point is available nor not.

Network service primitives Connectionless service primitives:

z N_UNITDATA request: A SCCP user requests the SCCP to transmit data to another SCCP.

z N_UNITDATA indication: SCCP notifies users that the user data are sent to the destination.

z N_NOTICE indication: SCCP notifies the originating user that the message cannot be sent to the destination.

z Connection-oriented service primitives: z N_CONNECT request: The message from the calling SCCP User to SCCP is used to

start the connection establishment procedure to establish a signaling connection. z N_CONNECT indication: It is sent from SCCP to request the called SCCP User to

establish signaling connection with the calling MS. z N_CONNECT response: It is sent from SCCP to notify the called SCCP User that it

agrees to establish signaling connection. z N_CONNECT acknowledgement: The calling SCCP notifies the calling MS to confirm

the establishment of the signaling connection. z N_DATA request: SCCP User requests SCCP to transfer data. z N_DATA indication: SCCP notifies the SCCP User that the user data have been sent to

the destination. z N_DISCONNECT request: SCCP User requests SCCP to reject or terminate the

signaling connection. z N_DISCONNECT indication: SCCP notifies the SCCP User that the signaling

connection has been rejected or terminated.



2.5.2 Operation and Options

Overview Trace messages based on a certain signaling link, capture and save all or part messages through the signaling link. It provides functions to open and display the files traced and saved for the SS7 messages. Log in the BSC Maintenance System, select the menu item [SS7 Maintenance/SS7 Message Trace/SS7 Message Tracing], and an interface will pop up, as shown in Figure 2-20.

Figure 2-20 SS7 message trace

The functions of the submenus under [SS7 Message Trace] are listed in Table 2-1.

Table 2-1 Submenus under the menu item [SS7 Message Trace]

Menu item Function

SS7 Message Tracing Trace a certain SS7

SS7 Message Review Open a SS7 message trace file in the saving media

Functions This function is used to trace messages based on a certain signaling link, capture all or part of the messages through this link. It can also be used to view whether the signaling coordination between offices is correct in case of problems in signaling coordination between different systems.




Operations Select the menu item [SS7 Maintenance/SS7 Message Trace/SS7 Message Traced], and an interface will pop up, as shown in Figure 2-21.

Figure 2-21 Setting for SS7 message tracing

Interface description Module No.: No. of the module where the SS7 link is located.

Link No.: No. of the link to be traced.

Message Type: Message type to be observed. The messages with the type to be selected will be listed in the trace results. Table 2-2 shows the descriptions of the message types.

Table 2-2 Meanings of message types

Message type Meaning

SNM Signaling network management message, MPT L3-message.

SLT Signaling link test message, MTP L3-message.

SCCP Signaling connection and control part message.

TUP TUP message, not used by BSC.

ISUP ISDN user part message, not used by BSC.

MT Maintenance test message.

UNKNOWN Unknown message.

L2_CHANGE MTP L2-message.

Filter: It is used to filter messages of the specified type. For instance, you can observe a message sent to a signaling point by setting the value of DPC_Filter. Once a filter is selected, the corresponding box in [Parameter] will become valid, and you can input the specified value. Table 2-3 shows the details of the filters.



Table 2-3 Meanings of filters

Filter Meaning

NI_Filter Network indicator (NI) filter: International-0, international reserved-1, national 2 and national reserved-3.

OPC_Filter Original signaling point code (OPC) filter: The OPC value is required.

DPC_Filter Destination signaling point code (DPC) filter: The DPC value is required.

H1_Filter H1 filter in MSU.

H0_Filter H0 filter in MSU (the specified messages can be filtered by setting both filters H1 and H0).

SLS_Filter Signaling link selection (SLS) code filter: SLS value is required.

CIC_Filter Circuit identification code filter: CIC value is required.

Direction_Filter Signaling direction filter: 0 for Tx; 1 for Rx.

If the user selects the check box "Save to file (No Extension Name)", and inputs the file name (without suffix) in the text box, the system will trace the information and save it for future review and analysis.

After setting all the trace items, click the button to start tracing. If an item is not set correctly, e.g., to trace a link actually not installed, the system will prompt "Sorry. Tracing MSU failed".

If the trace item is correctly set, a window shown in Figure 2-23 will pop up, indicating the start of trace.

Figure 2-22 SS7 trace window




The title of the window shows the No. of the module where the link being traced is located and the link ID.

Once a message conformable to the trace requirement is traced, it will be listed in the trace window. When the number of messages exceeds the display range in the window, you can use the scrollbar for browse. The items in the message list are described as follows:

[Service]: Service type of the messages. Figure 2-22 lists TEST messages. The symbols on the left of the window refer to the directions in which the messages are sent. "" for message receiving. At the same time, the messages in blue are that sent, and the messages in black are that received.

[SubSer]: Sub service-type of the message. "INT" for national reserved network.

[Time]: Time the message is generated. It is a value relative to the start of trace.

[H1H0]: Name of the message.

[CIC/SLC]: CIC/SLC value in the message, indicating different meanings based on different message structures.

[SLS]: Value of the signaling link selection code.

[OPC]: OPC value in the message structure.

[DPC]: DPC value in the message structure.

[Signal Message...]: Parameters in the message, denoted by hexadecimal numerals.

To pause message trace, press and the window will display the message in "Pause" state and the number of "Pause" times and time. Press again, and the window will display to "Continue" the message, and the number of "Resume" times and time, and the message trace will be resumed.

When the personnel have some knowledge about the SS7 message structure, they can get the message Tx/Rx and contents by analyzing the trace results.

Service SubSer Time H1H0 CIC/SLC SLS

SCCP INT 471 - - 009

OPC DPC Signal Message...

0B51 0B5A 06 01 00 41 00 01 06 01 00 03 05 04 11

The message is a location update reject message. The OPC is 0B51, and DPC is 0B5A. "06" in the message parameter refers to the SCCP DT1 message. "01 00 41" is the destination local reference. "00" is the segmentation/reassembly mark, indicating there is no more data. "01" is user data offset, and "06" is user data length. "01 00 03" refers to the DTAP message, and the message length "03" is DTAP. "05 04 11" refers to MM (05) sublayer location update rejected (04), and the cause is system fault (11).

Close the window and the trace will be stopped.



2.5.3 Examples Messages traced through the SS7 trace function provided by the BSC Maintenance System:

Figure 2-23 SS7 message tracing window

Descriptions of the messages in Figure 2-23.

z Select a message, press or double click on it to view the details of the message content.

z The message with ">" before, i.e., the message in black, indicates that the formal message signal units (MSU) are received from this link.

z The message with "" or "




PARA: Command or response parameter. It refers to a board type. 00 is for the LPN7 board, and 01 for SS7 board. The parameters followed are commands or command responses, please refer to the details of the messages.

Only the content following PARA is used in the examples for the messages of this type.

The first message in the "SS7 Message Tracing window" can be briefly described as follows: In the 19.7th second since the opening of the message tracing window, MTP delivers a STOP command to this signaling link.

MSU transmitted in the link:

Service: Service indication of the message. Test refers to signaling link test messages, MPT refers to the signaling network management messages in MTP, and TUP, ISUP and SCCP refer to the messages in TUP, ISUP and SCCP respectively.

SubSer: Sub service field, i.e., NI. NAT is for national network, and INT for international network.

Time: time (unit: 10ms), it is a relative time, i.e., the time interval from the start of the signaling link trace to the generation of the message. The maximum value is 65535. It is counted from 0 upon the reach to the maximum value.

H1H0: Message header code, used to identify a specific message.

CIC/SLC: CIC for the TUP and ISUP messages, SLC for the MTP messages, and SLS for the SCCP messages.

SLS: Signaling link selection code. It is displayed for the ISUP messages only.

OPC: Originating signaling point code in the message.

DPC: Destination signaling point code in the message.

Signal Message: Contents of the message.



2.6 SCCP Signaling Trace 2.6.1 Functions

SCCP, signaling connection control part in SS7, is an important approach to locate and solve problems in deployment, maintenance and debugging. The OMC of Huawei provides the following functions for SCCP maintenance: Message Trace, Management Options and Status Query. The message trace function can be used to trace a SCCP message to be analyzed conveniently, and improve the efficiency in problem solution. Select the menu item [SS7 Maintenance/SCCP Maintenance], and an interface will pop up, as shown in Figure 2-24.

Figure 2-24 SCCP maintenance window

2.6.2 Operations SCCP signaling message trace function is an important approach to locate problems and provides reference for operation verification in deployment, maintenance and debugging. It is the most commonly used function in SCCP maintenance.




Trace parameter setting Select the menu item [SS7 Maintenance/SCCP Maintenance/SCCP Message Trace] in the BSC Maintenance System, and an interface will pop up, as shown in Figure 2-25.

Figure 2-25 SCCP message trace

Start tracing Start tracing after setting all the trace items. If an item is not correctly set, e.g., the digits of signaling point code is not enough, the system will prompt "Please input 3 digits of signaling point code".



If the item is correctly set, a window indicating the start of trace will pop up, as shown in Figure 2-26.

Figure 2-26 SCCP DPC message trace

The title bar of the window displays the NI and SPC of the message being traced.

"START TRACE NO.7 SUCCESS !" means the trace is successful.

The message once traced to be conformable to the trace requirement will be added to the window. When the number of messages exceeds the display range, you can use a scroll bar for browse. The meanings of the items in the message list are given as follows:

[MsgType]: Type of the message.

[Signal Message...]: Content of the message, denoted by hexadecimal numerals.

Pause/Resume Tracing To pause message trace, press and the window will display the message in "Pause" state and the number of "Pause" times, and time. Press again, the window will prompt to "Continue" the message, and the number of "Resume" times, and time. The message trace will be resumed.




2.6.3 Options


[Module No.]: Fixed as 1 for BSC.

[NI]: Indicating the signaling network where the remote signaling point is located. It includes "International active", "International standby", "National active" and "National standby". Generally

[SPC]: 6-digit hexadecimal code, queried from the data management console. It refers to the peer MSC SPC.

Whether [NI] and [SPC] are valid is independent on the trace object selected.

Select the message type to be observed, and the messages of the type will be listed in the trace results.

Trace message to far-end signaling point: Message sent to the far-end signaling point.

Trace message from far-end signaling point: Message sent from the far-end signaling point.

Trace MPT messages addressed by GT: SCCP provides several addressing modes. Select this item, and only the messages addressed by GT will be displayed.

Trace subscriber messages: Messages of SCCP subscribers, like TCAP message.



2.6.4 Examples The following figure show the SCCP messages traced when MS initiates a call, as shown in Figure 2-28.


Analysis for the bytes in the CR messages ("X" for the BITS to be analyzed, and "?" for those not to be analyzed for the moment).

Standard message format Message content Byte

????XXXX SI ????0011 Service indicator

??XX???? ??00???? Invalid field

??XXXXXX NI 11?????? Network indicator

0xC3

XXXXXXXX ??XXXXXX

DPC 10100010 ??000000

Destination signaling Point Code 00B2

XX?????? XXXXXXXX ????XXXX

OPC 01?????? 00110000 ????0000

Original signaling Point Code 00C1

XXXX???? SLS 1110???? Signaling link selection code 0E

0x50 0x34 0x0A 0XC0

XXXXXXXX Message type 00000001 CR message 0x01

3 bytes Source Local Reference

010041h Originating local code

0x01 0x00 0x41




Standard message format Message content Byte

????XXXX Protocol type ????0010 Services of Class 2

XXXX???? 0000???? Invalid field

0x02

1 byte Size variable mandatory pointer

00000010 Called address pointer

0x02

1 byte Any part start pointer 00000110 Pointing to calling address

0x06

1 byte Size indicator 04h Length of called address

0x04

???????X Signaling point indicator

???????1 SPC included

??????X? Subsystem indicator ??????1? SSN included

??XXXX?? GT indicator ??0000?? GT not included

?X?????? Routing indicator ?1?????? DPC and SSN routing

X??????? 0??????? National reserved

0x43

2 bytes SPC 0X5034 OPC 0x5034

1 byte SSN 0xfe A interface subsystem

0xFE

1 byte Any parameter name 0x04 Calling address 0x04

5 bytes Any parameter name 04 43 28 10 FE

Format same as the called address

04 43 28 10 FEh

1 byte Any parameter name 0x0F SCCP user data 0x0F

1 byte Any parameter size 0x1c SCCP user data size (followed by BSSAP messages)

0x1c

ContentsFiguresTables2 Signaling Trace GuideAbout This Chapter2.1 Overview2.2 Um Interface Trace2.2.1 Functions2.2.2 Operations2.2.3 Options2.2.4 Examples

2.3 Abis Interface Trace2.3.1 Functions2.3.2 Operations2.3.3 Options2.3.4 Examples

2.4 A Interface Trace2.4.1 Functions2.4.2 Operations2.4.3 Options2.4.4 Examples

2.5 SS7 Trace2.5.1 Functions2.5.2 Operation and Options2.5.3 Examples

2.6 SCCP Signaling Trace2.6.1 Functions2.6.2 Operations2.6.3 Options2.6.4 Examples

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01-2 Signaling Trace Guide

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