Cisco PGW 2200 Softswitch

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Introduction

Transaction Capabilities Applications Part (TCAP) provides support for interactive applications in a distributed environment. TCAP defines an end-to-end protocol between its users. This may be located in an SS7 network or another network that supports TCAP (IP).

Prerequisites

Requirements

Readers of this document should have knowledge of:

• Cisco Media Gateway Controller Release 9

Components Used

The information in this document is based on the Cisco PGW 2200 Softswitch.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Background Information

The TCAP protocol consists of two sub-layers:

• Component sub-layer

• Transaction sub-layer

The component sub-layer interfaces with the conversion engine. The conversion engine is the equivalent of a service user or subsystem number (SSN). The component sub-layer supports these services:

• Association of operations and replies.

• Abnormal situation handling.

The transaction sub-layer interfaces with Signalling Connection Control Part (SCCP). TCAP only supports a connectionless network service. The transaction sub-layer communicates with SCCP through the connectionless interface.

TCAP software uses the services of SCCP software to route the messages to the TCAP user in the destination node. The interface between the TCAP and the SCCP software is tightly coupled. Each TCAP request from the engine contains a global title and destination subsystem number. TCAP provides the subsystem number to SCCP for the Signal Transfer Points (STP) code look-up. If the SS7 addresses and routes are configured correctly and fully operational, troubleshoot the SCCP and TCAP information passed and received between the Cisco PGW 2200 and a remote SCCP or TCAP peer.

The Cisco PGW 2200 uses the SCCP to encapsulate TCAP queries for transport out Message Transfer Part (MTP). This SCCP communication between peers is sent without a connection over MTP. The Cisco PGW 2200 uses the SCCP Unidata (UDT) to send data to the remote SCCP node for connectionless communication. The PGW 2200 receives a valid response when the SCCP UDT message is delivered successfully. This is typically in the form of a UDT message. The exchange of these UDT messages facilitates the connectionless communication between the PGW 2200 and the remote SCCP peer (such as Service Control Point [SCP] for TCAP data base lookups). The PGW 2200 defines an optional field in the UDT that states the SCCP peer should "return on error" the contents of any message it sends to the remote node if the UDT message is undeliverable. The Unidata service (UDTS) message is used to facilitate this error response. The UDTS message indicates to the PGW 2200 that a UDT message received at the remote node (such as STP or SCP) cannot be delivered to the destination.

TCAP Resolution

The SCCP messaging (UDT/UDTS) discussed in the Background Information section is critical when you troubleshoot TCAP services and functionality. Resolve any problems at the SCCP layer before you troubleshoot TCAP data sent or received. The format of the UDT and the UDTS message is shown in Appendix C.

Use these Cisco PGW 2200 tools to debug calls that require the TCAP (TCAP / SCCP) services:

• Sniffer the Ethernet line with tools such as Ethereal, UNIX snoop, and Snooper.

• Platform.log TCAP trace on the PGW 2200.

• MDL Trace Tool for call processing at the protocol level.

Sniffer the Ethernet Line

The Cisco PGW 2200 uses Reliable UDP (RUDP) to send MTP3 and upper layer SS7 messages between the local MTP1 and MTP2 devices (such as a Signaling Link Terminal [SLT]). This communication is typically done over port 7000 on the Cisco PGW 2200 local Ethernet interface. This is configurable. Refer to the configuration guide for details on configuring the PGW "stPort" ports in XECfgParm.dat.

You can use any Ethernet sniffer to view the packets sent between the Cisco PGW 2200 and its local MTP2 control device. However, not all of them support the MTP and SCCP protocol used to display a decoded message. If an Ethernet sniffer is not available to the customer, use the UNIX snoop command to troubleshoot. The output of the snoop command is not user friendly, but is helpful in a worst case scenario.

An Ethernet sniffer that supports the SS7 protocol stack is preferred. It allows you to decode packets seen on the Cisco PGW 2200 Ethernet interface. An open source sniffer such as Ethereal can also be used and is available online.

If no commercial sniffer utility is available, issue the snoop command on the target Cisco PGW 2200 to see the hex data output of the messages sent to and from the Cisco PGW 2200. With root permission on the Cisco PGW 2200, issue this command to see the hex data sent out of the configured 'stPort.' For additional information on the snoop command, refer to the 'snoop man pages' or the SUN Administrative guides.

#snoop -d <ethernet device name> -x 42 port <stPort>

Issue this command to snoop the packets sent out the Ethernet device, hmeX, on port 7000.

#snoop -d hmeX -x 42 port 7000

This is example output of captured SS7 packets with the snoop command.

Cisco's Snooper can also be used (if available) to show the hex dump of the SCCP message. The SCCP message header is decoded but the display of the output is dependant on the version of Snooper chosen. The important point is that the message type is visible and gives an indication as to where to start to troubleshoot the call flow. The hex dump shows that message type 09 is a UDT message and message type 0a is the UDTS service message that indicates an error. The direction of the message flow is also useful since the SS7 PCs are shown. If the rest of the hex dump is shown (depends on the snooper version) it can be used to further decode the SCCP and TCAP portions of message. This is based on the industry standards for SCCP and TCAP.

This is the Snooper output of the UDT SCCP message with TCAP data (to PSTN).

If there is an undeliverable SCCP UDT message sent from the Cisco PGW 2200 and / or an SCCP (on the remote node) has problems with the message, the Cisco PGW 2200 receives a UDTS response message. This message indicates a 'return cause' which is very useful in troubleshooting. The UDTS is message type 10 (or 0a hex).

This is an example of a UDTS SCCP message with TCAP data (from PSTN).

Note: This message is an example only and may not reflect an actual query response combination / sequence. The format and amount of information displayed varies depending on the Snooper version.

This Snooper output displays the IAM, UDT, UDTS, and REL sequence.

Note: This message is an example only and may not reflect an actual query response combination / sequence. The format and amount of information displayed varies depending on the Snooper version.

This is an SS7 sniffer trace that includes SS7 SCCP and TCAP information.

------------------------------------------------------------------------
SCP(IN)- 19/03/04 18:01:54:223     SCCP     SCP(IN)  UDT     SCP(IN)  BGN INVK IDP   
--------------------------------------------------------------------------------
     Octet001  ITU-T SS7              Time=19/03/02 18:01:54:223 
    --------------------------------------------------------------------------------
     11010011  BIB/BSN                 1/83 
     10010110  FIB/FSN                 1/22 
     ..111111  SU type/length         MSU63 
     00......  Spare                  0
    --------------------------------------------------------------------------------
     Octet004  Service information octet  
    --------------------------------------------------------------------------------
     ....0011  Service indicator      SCCP Signalling Connection Control Part 
     ..00....  Message priority       0
     10......  Network indicator      N  National network 
    --------------------------------------------------------------------------------
     Octet005  Routing label         
    --------------------------------------------------------------------------------
     ........  DPC                    10337 SCP(IN) 
     ........  OPC                    10321   
     0001....  SLS                    1
    --------------------------------------------------------------------------------
     Octet009  Message type          
    --------------------------------------------------------------------------------
     00001001  Message type           UDT   Unitdata 
    --------------------------------------------------------------------------------
     Octet010  SCCP Protocol Class parameter  
    --------------------------------------------------------------------------------
     ....0001  Protocol class         Class 1 
     0000....  Message handling       No special options 
     00000011  Ptr -> Called number   3
     00000111  Ptr -> Calling #       7
     00001011  Pointer -> Data        11
    --------------------------------------------------------------------------------
     Octet014  SCCP Called Party Address parameter  
    --------------------------------------------------------------------------------
     00000100  Parameter length       4
     .......1  Sgnl pt code bit       SPC present 
     ......1.  Subsystem # bit        SSN present 
     ..0000..  Global title ind       No global title included 
     .1......  Routing bit            DPC and SSN based routing 
     0.......  Reserved natl use      0
     ........  Point code             10337 SCP(IN) 
     00......  Spare                  0
     11111100  Subsystem number       INAP     IN-CS1+ 
    --------------------------------------------------------------------------------
     Octet019  SCCP Calling Party Address parameter  
    --------------------------------------------------------------------------------
     00000100  Parameter length       4
     .......1  Sgnl pt code bit       SPC present 
     ......1.  Subsystem # bit        SSN present 
     ..0000..  Global title ind       No global title included 
     .1......  Routing bit            DPC and SSN based routing 
     0.......  Reserved natl use      0
     ........  Point code             10321 
     00......  Spare                  0
     11111100  Subsystem number       INAP      IN-CS1+ 
    --------------------------------------------------------------------------------
     Octet024  SCCP Data parameter   
    --------------------------------------------------------------------------------
     01100001  Parameter length       97
     01100010  Tag                    BGN Begin, constructor, application-wide 
     01011111  Length                 95
    --------------------------------------------------------------------------------
     Octet027  Originating Transaction ID  
    --------------------------------------------------------------------------------
     ...01000  Tag                    Originating Transaction ID 
     010.....  Class and form         Application-wide, primitive 
     00000011  Length                 3
     ........  Originating ID        F30051 
    --------------------------------------------------------------------------------
     Octet032  TCAP Dialogue Portion 
    --------------------------------------------------------------------------------
     ...01011  Tag                    TCAP Dialogue Portion 
     011.....  Class and form         Application-wide, constructor 
     00100011  Length                 35
    --------------------------------------------------------------------------------
     Octet034  TCAP External         
    --------------------------------------------------------------------------------
     ...01000  Tag                    TCAP External 
     001.....  Class and form         Universal, constructor 
     00100001  Length                 33
    --------------------------------------------------------------------------------
     Octet036  Object identifier     
    --------------------------------------------------------------------------------
     ...00110  Tag                    Object identifier 
     000.....  Class and form         Universal, primitive 
     00000111  Length                 7
     00000000  Organization           itu-t recommendation 
     00010001  q                       Q 
     ........  773 (X'305)            773
     00000001  as(1)                  1
     00000001  Protocol data unit     dialogue PDU(1) 
     00000001  version(1)             1
     10100000  Single-ASN.1-typeTag   Parameter 
     00010110  Length                 22
    --------------------------------------------------------------------------------
     Octet047  Dialogue request      
    --------------------------------------------------------------------------------
     ...00000  Tag                    Dialogue request 
     011.....  Class and form         Application-wide, constructor 
     00010100  Length                 20
    --------------------------------------------------------------------------------
     Octet049  Protocol-version      
    --------------------------------------------------------------------------------
     ...00000  Tag                    Protocol-version 
     100.....  Class and form         Context-specific, primitive 
     00000010  Length                 2
     00000111  Unused Bit             07
     .0000000  Unused Bit             00
     1.......  Protocol Version       Version 1 
    --------------------------------------------------------------------------------
     Octet053  Application-context-name  
    --------------------------------------------------------------------------------
     ...00001  Tag                    Application-context-name 
     101.....  Class and form         Context-specific, constructor 
     00001110  Length                 14
    --------------------------------------------------------------------------------
     Octet055  Object Identifier     
    --------------------------------------------------------------------------------
     ...00110  Tag                    Object identifier 
     000.....  Class and form         Universal, primitive 
     00001100  Length                 12
     00101010  Protocol               ccitt identified-organization 
     10000110  SubProtocol            etsi 
     00111010  Domain                 inDomain 
     00000000  Network                in-Network 
     10001001  AC Name                ac (application context) 
     01100001  Service                cs1-ssp-to-scp(0) 
     00110011  Version                Reserved 
     ........  Contents               01 00 01 00 01
    --------------------------------------------------------------------------------
     Octet069  TCAP Component Portion  
    --------------------------------------------------------------------------------
     ...01100  Tag                    TCAP Component Portion 
     011.....  Class and form         Application-wide, constructor 
     10000000  Length                 128
    --------------------------------------------------------------------------------
     Octet071  Invoke component      
    --------------------------------------------------------------------------------
     ...00001  Tag                    Invoke component 
     101.....  Class and form         Context-specific, constructor 
     00101111  Length                 47
    --------------------------------------------------------------------------------
     Octet073  Invoke ID             
    --------------------------------------------------------------------------------
     ...00010  Tag                    Invoke ID 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     00000001  Invoke ID              01
    --------------------------------------------------------------------------------
     Octet076  Operation Code        
    --------------------------------------------------------------------------------
     ...00010  Tag                    Local 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     ........  Operation Code         IDP  InitialDP 
    --------------------------------------------------------------------------------
     Octet079  Parameter Sequence    
    --------------------------------------------------------------------------------
     ...10000  Tag                    Parameter Sequence 
     001.....  Class and form         Universal, constructor 
     00100111  Length                 39
    --------------------------------------------------------------------------------
     Octet081  ServiceKey            
    --------------------------------------------------------------------------------
     ...00000  Tag                    ServiceKey 
     100.....  Class and form         Context-specific, primitive 
     00000001  Length                 1
     ........  Service key            94
    --------------------------------------------------------------------------------
     Octet084  CalledPartyNumber     
    --------------------------------------------------------------------------------
     ...00010  Tag                    CalledPartyNumber 
     100.....  Class and form         Context-specific, primitive 
     00000111  Length                 7
     .0000011  Nature of address      National (significant) number( national use ) 
     1.......  Odd/even               Odd number of address signals 
     ....0000  Spare                  00
     .001....  Numbering plan         ISDN (Telephony) numbering plan (Rec. E.164) 
     1.......  Internal network #     Routing to internal network number not allowed 
     ........  Address signals       999956738 
     0000....  Filler                 0
    --------------------------------------------------------------------------------
     Octet093  CallingPartyNumber    
    --------------------------------------------------------------------------------
     ...00011  Tag                    CallingPartyNumber 
     100.....  Class and form         Context-specific, primitive 
     00000111  Length                 7
     .0000011  Nature of address      National (significant) number( national use ) 
     1.......  Odd/even               Odd number of address signals 
     ......01  Screening Indicator    User provided, verified and passed 
     ....00..  Presentation?          Presentation allowed 
     .001....  Numbering plan         ISDN (Telephony) numbering plan (Rec. E.164) 
     0.......  Number Incomplete?     Complete 
     ........  Address signals       2199997137 
     0000....  Filler                 0
    --------------------------------------------------------------------------------
     Octet102  CallingPartysCategory 
    --------------------------------------------------------------------------------
     ...00101  Tag                    CallingPartysCategory 
     100.....  Class and form         Context-specific, primitive 
     00000001  Length                 1
     00001010  CallngPartyCategory    Ordinary calling subscriber 
    --------------------------------------------------------------------------------
     Octet105  ForwardCallIndicators 
    --------------------------------------------------------------------------------
     ...11010  Tag                    ForwardCallIndicators 
     100.....  Class and form         Context-specific, primitive 
     00000010  Length                 2
     .......0  Nat'l/International    Call to be treated as a national call 
     .....00.  End-to-end method      No end-to-end method available 
     ....1...  Interworking           Interworking encountered 
     ...0....  End-to-end info        No end-to-end information available 
     ..1.....  ISUP indicator         ISDN user part used all the way 
     01......  ISUP preference        ISDN user part not required all the way 
     .......1  Orig ISDN access       Originating access ISDN 
     .....00.  SCCP method            No indication 
     ....0...  Spare                  0
     0000....  ReservedForNat'lUse    0
    --------------------------------------------------------------------------------
     Octet109  BearerCapability      
    --------------------------------------------------------------------------------
     ...11011  Tag                    BearerCapability 
     101.....  Class and form         Context-specific, constructor 
     00000101  Length                 5
    --------------------------------------------------------------------------------
     Octet111  Bearer Cap            
    --------------------------------------------------------------------------------
     ...00000  Tag                    Bearer Cap 
     100.....  Class and form         Context-specific, primitive 
    --------------------------------------------------------------------------------
     Octet112  User service information parameter  
    --------------------------------------------------------------------------------
     00000011  Parameter length       3
    --------------------------------------------------------------------------------
     Octet113  User service info octet 3  
    --------------------------------------------------------------------------------
     ...00000  Transfer capability    Speech 
     .00.....  Coding standard        CCITT standardized coding 
     1.......  Extension bit          1
    --------------------------------------------------------------------------------
     Octet114  User service info octet 4  
    --------------------------------------------------------------------------------
     ...10000  Transfer rate          64 kbit/s 
     .00.....  Transfer mode          circuit mode 
     1.......  Extension bit          1
    --------------------------------------------------------------------------------
     Octet115  User service info octet 5  
    --------------------------------------------------------------------------------
     ...00011  Layer 1 protocol       Recommendation G.711 A-law 
     .01.....  Layer 1 Identifier     User information layer 1 protocol 
     1.......  Extension bit          1
    --------------------------------------------------------------------------------
     Octet116  CalledPartyNumber     
    --------------------------------------------------------------------------------
     ...00010  Tag                    CalledPartyNumber 
     110.....  Class and form         Private use, primitive 
     00000010  Length                 2
     .0000000  Nature of address      Spare 
     0.......  Odd/even               Even Number of Address signals 
     ....1010  Spare                  0A
     .000....  Numbering plan         Spare (no interpretation) 
     0.......  Internal network #     Routing to internal network number allowed 
    --------------------------------------------------------------------------------
     Octet120  End-of-contents       
    --------------------------------------------------------------------------------
     00000000  Tag                    00
     00000000  Length                 00
    --------------------------------------------------------------------------------
     Checksum  CRC16................  0001011001110111 hex=1677
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------


SCP(IN)- 19/03/04  18:01:54:269   SCCP   SCP(IN)   UDT    SCP(IN) CON INVK CUE  

    --------------------------------------------------------------------------------
     Octet001  ITU-T SS7              Time=19/03/02 18:01:54:269 
    --------------------------------------------------------------------------------
     10000001  BIB/BSN                 1/1  
     10110010  FIB/FSN                 1/50 
     ..111111  SU type/length         MSU63 
     00......  Spare                  0
    --------------------------------------------------------------------------------
     Octet004  Service information octet  
    --------------------------------------------------------------------------------
     ....0011  Service indicator      SCCP Signalling Connection Control Part 
     ..00....  Message priority       0
     10......  Network indicator      N  National network 
    --------------------------------------------------------------------------------
     Octet005  Routing label         
    --------------------------------------------------------------------------------
     ........  DPC                    10321 
     ........  OPC                    10337 SCP(IN) 
     1010....  SLS                    10
    --------------------------------------------------------------------------------
     Octet009  Message type          
    --------------------------------------------------------------------------------
     00001001  Message type           UDT   Unitdata 
    --------------------------------------------------------------------------------
     Octet010  SCCP Protocol Class parameter  
    --------------------------------------------------------------------------------
     ....0001  Protocol class         Class 1 
     0000....  Message handling       No special options 
     00000011  Ptr -> Called number   3
     00000111  Ptr -> Calling #       7
     00001011  Pointer -> Data        11
    --------------------------------------------------------------------------------
     Octet014  SCCP Called Party Address parameter  
    --------------------------------------------------------------------------------
     00000100  Parameter length       4
     .......1  Sgnl pt code bit       SPC present 
     ......1.  Subsystem # bit        SSN present 
     ..0000..  Global title ind       No global title included 
     .1......  Routing bit            DPC and SSN based routing 
     0.......  Reserved natl use      0
     ........  Point code             10321 Matinha 
     00......  Spare                  0
     11111100  Subsystem number       INAP     IN-CS1+ 
    --------------------------------------------------------------------------------
     Octet019  SCCP Calling Party Address parameter  
    --------------------------------------------------------------------------------
     00000100  Parameter length       4
     .......1  Sgnl pt code bit       SPC present 
     ......1.  Subsystem # bit        SSN present 
     ..0000..  Global title ind       No global title included 
     .1......  Routing bit            DPC and SSN based routing 
     0.......  Reserved natl use      0
     ........  Point code             10337 SCP(IN) 
     00......  Spare                  0
     11111100  Subsystem number       INAP     IN-CS1+ 
    --------------------------------------------------------------------------------
     Octet024  SCCP Data parameter   
    --------------------------------------------------------------------------------
     01001001  Parameter length       73
     01100101  Tag                    CON Continue, constructor, application-wide 
     01000111  Length                 71
    --------------------------------------------------------------------------------
     Octet027  Originating Transaction ID  
    --------------------------------------------------------------------------------
     ...01000  Tag                    Originating Transaction ID 
     010.....  Class and form         Application-wide, primitive 
     00000011  Length                 3
     ........  Originating ID        7A01B4 
    --------------------------------------------------------------------------------
     Octet032  Destination Transaction ID  
    --------------------------------------------------------------------------------
     ...01001  Tag                    Destination Transaction ID 
     010.....  Class and form         Application-wide, primitive 
     00000011  Length                 3
     ........  Destination ID        F30051 
    --------------------------------------------------------------------------------
     Octet037  TCAP Dialogue Portion 
    --------------------------------------------------------------------------------
     ...01011  Tag                    TCAP Dialogue Portion 
     011.....  Class and form         Application-wide, constructor 
     00101111  Length                 47
    --------------------------------------------------------------------------------
     Octet039  TCAP External         
    --------------------------------------------------------------------------------
     ...01000  Tag                    TCAP External 
     001.....  Class and form         Universal, constructor 
     00101101  Length                 45
    --------------------------------------------------------------------------------
     Octet041  Object identifier     
    --------------------------------------------------------------------------------
     ...00110  Tag                    Object identifier 
     000.....  Class and form         Universal, primitive 
     00000111  Length                 7
     00000000  Organization           itu-t recommendation 
     00010001  q                       Q 
     ........  773 (X'305)            773
     00000001  as(1)                  1
     00000001  Protocol data unit     dialogue PDU(1) 
     00000001  version(1)             1
     10100000  Single-ASN.1-typeTag   Parameter 
     00100010  Length                 34
    --------------------------------------------------------------------------------
     Octet052  Dialogue response     
    --------------------------------------------------------------------------------
     ...00001  Tag                    Dialogue response 
     011.....  Class and form         Application-wide, constructor 
     00100000  Length                 32
    --------------------------------------------------------------------------------
     Octet054  Protocol-version      
    --------------------------------------------------------------------------------
     ...00000  Tag                    Protocol-version 
     100.....  Class and form         Context-specific, primitive 
     00000010  Length                 2
     00000111  Unused Bit             07
     .0000000  Unused Bit             00
     1.......  Protocol Version       Version 1 
    --------------------------------------------------------------------------------
     Octet058  Application-context-name  
    --------------------------------------------------------------------------------
     ...00001  Tag                    Application-context-name 
     101.....  Class and form         Context-specific, constructor 
     00001110  Length                 14
    --------------------------------------------------------------------------------
     Octet060  Object Identifier     
    --------------------------------------------------------------------------------
     ...00110  Tag                    Object identifier 
     000.....  Class and form         Universal, primitive 
     00001100  Length                 12
     00101010  Protocol               ccitt identified-organization 
     10000110  SubProtocol            etsi 
     00111010  Domain                 inDomain 
     00000000  Network                in-Network 
     10001001  AC Name                ac (application context) 
     01100001  Service                cs1-ssp-to-scp(0) 
     00110011  Version                Reserved 
     ........  Contents               01 00 01 00 01
    --------------------------------------------------------------------------------
     Octet074  Result                
    --------------------------------------------------------------------------------
     ...00010  Tag                    Result 
     101.....  Class and form         Context-specific, constructor 
     00000011  Length                 3
    --------------------------------------------------------------------------------
     Octet076  Integer               
    --------------------------------------------------------------------------------
     ...00010  Tag                    Integer 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     ........  Value                  accepted 
    --------------------------------------------------------------------------------
     Octet079  Result-source-diagnostic  
    --------------------------------------------------------------------------------
     ...00011  Tag                    Result-source-diagnostic 
     101.....  Class and form         Context-specific, constructor 
     00000101  Length                 5
    --------------------------------------------------------------------------------
     Octet081  Dialogue service user 
    --------------------------------------------------------------------------------
     ...00001  Tag                    Dialogue service user 
     101.....  Class and form         Context-specific, constructor 
     00000011  Length                 3
    --------------------------------------------------------------------------------
     Octet083  Integer               
    --------------------------------------------------------------------------------
     ...00010  Tag                    Integer 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     ........  Value                  Null 
    --------------------------------------------------------------------------------
     Octet086  TCAP Component Portion  
    --------------------------------------------------------------------------------
     ...01100  Tag                    TCAP Component Portion 
     011.....  Class and form         Application-wide, constructor 
     10000000  Length                 128
    --------------------------------------------------------------------------------
     Octet088  Invoke component      
    --------------------------------------------------------------------------------
     ...00001  Tag                    Invoke component 
     101.....  Class and form         Context-specific, constructor 
     00000110  Length                 6
    --------------------------------------------------------------------------------
     Octet090  Invoke ID             
    --------------------------------------------------------------------------------
     ...00010  Tag                    Invoke ID 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     00000001  Invoke ID              01
    --------------------------------------------------------------------------------
     Octet093  Operation Code        
    --------------------------------------------------------------------------------
     ...00010  Tag                    Local 
     000.....  Class and form         Universal, primitive 
     00000001  Length                 1
     ........  Operation Code         CUE  Continue 
    --------------------------------------------------------------------------------
     Octet096  End-of-contents       
    --------------------------------------------------------------------------------
     00000000  Tag                    00
     00000000  Length                 00
    --------------------------------------------------------------------------------
     Checksum  CRC16................  0011010011100010 hex=34E2
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------

Troubleshoot Tip: UDTS Return Cause

For a UDTS message, the 'return cause' is the first byte after the message type 0a. This value helps determine why the STP / SCP sends a UDTS error response. If this information is not visible in the sniffer, proceed to the Platform.log TCAP Trace section in order to enable TCAP traces in the Cisco PGW 2200 log.

Platform.log TCAP Trace

MML allows a user to start a TCAP trace that dumps <Trace> messages for the TCAP channel controller into /opt/CiscoMGC/var/log/platform.log. A TCAP trace allows the user to see the TCAP / SCCP messages sent to the SS7 channel controller to route out to the SS7 switch over MTP3. See Appendix E for the message flow of a TCAP query through the PGW 2200 software.

TCAP tracing is started via mml with the sta-tcap-trc command. In order to capture the relevant information, enable debug logging for the TCAP and SS7 channel controller.

This is an example of how to enable a TCAP trace:

mml> set-log:TCAP-01:debug,confirm

   MGC-01 - Media Gateway Controller 2004-03-26 11:17:31.503 EST

M  COMPLD

   "TCAP-01"

   ;

mml> set-log:ss7-i-1:debug,confirm

   MGC-01 - Media Gateway Controller 2004-03-26 11:17:40.715 EST

M  COMPLD

   "ss7-i-1"

   ;

mml> sta-tcap-trc

   MGC-01 - Media Gateway Controller 2004-03-26 11:05:27.040 EST

M  RTRV

   SROF

   "TCAP-01"

   /* Component already started */

   ;

Note: Debug logging can have an effect on system performance and should not be used in a production environment under high call volume. Please plan your maintenance window accordingly.

TCAP Messages Sent by the Cisco PGW 2200

Once an IN_TRIGGER is sent to the engine, the engine beings to send the message out of the PGW 2200. Information passed down from the protocol level is relayed to the TCAP channel controller. The TCAP portion is sent down to the SCCP channel controller. Also, a log is created in platform.log to indicate a TCAP message was 'transmitted'. From the previous UDT message (shown in the sniffer portion of this document) you can see how the PGW 2200 logs information related to this same message in the platform.log. This platform log matches the data content shown in the Sample SCCP Message Breakdown: Unitdata / Unitdata Service table in Appendix C. From this table, the first value is the data length value (52 hex = 82 decimal). The actual TCAP data portion follows the message length. In the event that sniffer or snooper is not available, this platform.log can be used to view / debug TCAP and SCCP transactions.

Troubleshoot Tip: If the TCAP message is not sent down to SCCP, there is a problem at the MDL or Engine level. Troubleshoot the MDL trace and look at the Ltrigger and LTriggerRelease signal.

This output shows the PGW 2200 log sending TCAP down stack to SCCP/MTP.

After TCAP sends the message to SCCP, the SS7 channel controller plays RECEIVED MSG FROM SCCP and logs the hex representation of the message to indicate receipt of the message. This hex dump includes the SCCP and TCAP portions as shown in this output.

• Use the SCCP message format shown in Appendix C to decode the message type, SCCP header information (shown in the output in yellow) and the beginning of the TCAP data (shown in the output in blue). The 1e0002 in the output represents the destination point code from dpc.dat and the SCCP message dump begins immediately after type "1" (beginning with SCCP message type).

• The PGW 2200 logs counter and Alarms for SCCP, TCAP and SS7 events. If measurements are enabled, check the counters for the TCAP message. Also check the SCCP, UDT, and UDTS received and transmitted. Refer to these documents for MGC operational procedures.

  • Managing System Measurements

  • Cisco MGC Measurements

  • Retrieving TCAP Transactions

• If the SS7 channel controller does not receive the message sent out of the PGW 2200, verify that TCAP transmitted a message down to SCCP. If the TCAP layer transmits the message down, it can be because the SCCP does not have enough information to build the proper SCCP message. This may also be an indication that the SS7 subsystem is not provisioned properly or is not available. Check this list to verify:

  • SS7 Point code configuration and status

  • SS7 Subsystem configuration

  • SS7 Subsystem routing configuration

  • Local and Remote SSN status

  • IN Service configuration (trigger.dat)

    System Verification

    mml>rtrv-spc:all
    
       MGC-01 - Media Gateway Controller 2004-03-26 13:22:05.492 EST
    
    M  RTRV
    
       "ss7svc1:DPC=001.022.001,DNW=2:OPC=001.001.001:IS"
    
       "ss7svc2:DPC=001.022.002,DNW=2:OPC=001.001.001:IS"
    
       "itussn1:DPC=001.004.001,DNW=2:OPC=001.001.001:IS"
    
       "itussn2:DPC=001.003.001,DNW=2:OPC=001.001.001:IS"
    
       "itussn3:DPC=001.004.001,DNW=2:OPC=001.001.001:IS"
    
       ;
    
    mml> prov-rtrv:ss7subsys:NAME="itussn1"
    
       MGC-01 - Media Gateway Controller 2004-03-26 11:48:26.321 EST
    
    M  RTRV
    
       "session=fix551tgp:ss7subsys"
    
       /* 
    
    NAME = itussn1
    
    DESC = pc_ssn rte-ssn 48
    
    SVC = scp1
    
    PRI = 1
    
    MATEDAPC = 
    
    LOCALSSN = 101
    
    PROTO = SS7-ITU
    
    STPSCPIND = 1
    
    TRANSPROTO = SCCP
    
    OPC = opc1
    
    SUAKEY = 
    
    REMOTESSN = 48
    
       */
    
       ;
    
    mml> rtrv-lssn:all                     
    
       MGC-01 - Media Gateway Controller 2004-03-26 11:49:01.985 EST
    
    M  RTRV
    
       "TCAP-01:SSN=12,PST=IS"
    
       "TCAP-01:SSN=101,PST=IS"
    
       "TCAP-01:SSN=102,PST=IS"
    
       ;
    
    mml> rtrv-rssn:all
    
       MGC-01 - Media Gateway Controller 2004-03-26 11:49:04.695 EST
    
    M  RTRV
    
       "scp1:PC=001.004.001,SSN=12,PST=IS"
    
       "scp1:PC=001.004.001,SSN=48,PST=IS"
    
       ;
    
    mml> prov-rtrv:inservice:name="finap-initdp"      
    
       MGC-01 - Media Gateway Controller 2004-03-29 14:45:25.738 EST
    
    M  RTRV
    
       "session=fix551tgp:inservice"
    
       /* NAME = finap-initdp
    
    SKORTCV = 90001
    
    GTORSSN = ROUTEBYSSN
    
    GTFORMAT = NOGT
    
    MSNAME = finap-initdp
    
       */
    
    ;
    
    mml> prov-rtrv:SS7ROUTE:NAME="route4"
    
       MGC-01 - Media Gateway Controller 2004-03-30 11:53:08.493 EST
    
    M  RTRV
    
       "session=fix551tgp:SS7ROUTE"
    
       /* 
    
    NAME = route4
    
    DESC = rte to 1.4.1 scp1
    
    OPC = opc1
    
    DPC = scp1
    
    LNKSET = ls3
    
    PRI = 1
    
       */
    
       ;

• If all of this information appears to be correct (as shown in the output displayed above) verify the tagged values sent down from the TCAP protocol level such as the SSN, SCCPCalledParty address and / or SCCPCallingParty address.

TCAP Messages that enter the Cisco PGW 2200

The reverse logic can be used to trace an SS7 message that comes into the Cisco PGW 2200 that is destined to the TCAP / SCCP user layer of the SS7 stack. The PGW 2200 logs show the SS7 message that comes into the SS7 channel controller (from the SS7 line) and is sent to TCAP for processing. The message is broken down at each layer of the SS7 stack. Also, note the OPC/DPC, Service Indicator (SIO) and signaling link selection (SLS). The OPC and DPC is represented in ITU format (in this example only).

Troubleshoot Tip: Verify the message type received from the SS7 line. If a UDTS message is receive check the 'return cause'.

This output shows the PGW 2200 log when it receives SCCP messages from the SS7 line:

Troubleshoot Tip: Use the SCCP message format shown in Appendix C to decode the message type, SCCP header information (shown in the output in yellow) and the start of the TCAP data. The 1e0002 in the output above represents the calling address (OPC) for the message received at the PGW as represented in dpc.dat. The SCCP message dump begins immediately after the "0" (beginning with SCCP message type).

This output is from the PGW 2200 log when it receives UDTS TCAP over SCCP/MTP:

Thu Mar 25 18:35:35:385 2004 EST | ss7-i-1 (PID 27288) <Debug>

CP Received PDU from ssetId 3, chan 0

Thu Mar 25 18:35:35:385 2004 EST | ss7-i-1 (PID 27288) <Trace>

PROT_TRACE_MTP3_PDU: Hex dump of MTP3 and UP messages 1d0005 0 
CP DATA IND len: 68 data: 83 09 48 08 a2 0a

 

Thu Mar 25 18:35:35:385 2004 EST | ss7-i-1 (PID 27288) <Debug>

 >>>> from: 821 to opc 809 (bytes 63) sio 83 sls a:

 

Thu Mar 25 18:35:35:385 2004 EST | ss7-i-1 (PID 27288) <Trace>

PROT_TRACE_MTP3_PDU: Hex dump of MTP3 and UP messages 1e0002 0 0a 01 03 0d 
11 04 ffffffc3 09 08 65 0a ffffff8b 21 08 30 00 18 38 33 44 44 29  62 
27 48 01 02 6c 22 ffffffa1 20 02 01 01 02 01 00 30 18 ffffff80 04 00 00 
00 01 ffffff82 07 01 10 18 38 33 44 44 ffffff83 07 01 11 07 13 11 00 10

 

Thu Mar 25 18:35:35:385 2004 EST | TCAP (PID 27283) <Debug>

Got 91 bytes from fifo /tmp/sccp_input (fd=16)

 

Thu Mar 25 18:35:35:385 2004 EST | ss7-i-1 (PID 27288) <Debug>

RECEIVED SCCP STACK MSG    

!--- Indicates message is from MTP(SS7 stack).



!--- Lines omitted.


Thu Mar 25 18:35:35:385 2004 EST | TCAP (PID 27283) <Debug>

00 01 00 01 1E 00 15 00 00 00 1A 00 00 02 00 00 00 00 00 00 08 21 00 00 
08 09 FFF0A 0A 01 03 0D 11 04 FFF09 08 65 0A FFF21 08 30 00 18 38 33 44 
44 29 62 27 48 01 02 6C 22 FFF20 02 01 01 02 01 00 30 18 FFF04 00 00  00 
01 FFF07 01 10 18 38 33 44 44 FFF07 01 11 07 13 11 00 10

 

Thu Mar 25 18:35:35:386 2004 EST | TCAP (PID 27283) <Debug>

ioTcSuIntfc::handleNotInd: Cause =1

 

Thu Mar 25 18:35:35:386 2004 EST | TCAP (PID 27283) <Debug>

Calling StUiStuDatReq(), spId = 1

 

Thu Mar 25 18:35:35:386 2004 EST | TCAP (PID 27283) <Debug>

Deleted spDlgEntry 2-69

 

Thu Mar 25 18:35:35:386 2004 EST | TCAP (PID 27283) <Debug>

Sending msgType 15 to Engine   

!--- TCAP sends response to Engine which is translated into L.

This output is from the PGW 2200 log when it receives an invalid TCAP message over SCCP / MTP:

MDL Trace Tool

The Cisco PGW 2200 uses triggers to initiate a TCAP transaction. TCAP protocol transactions use the IN_TRIGGER method to send and receive messages to and from the TCAP control layer. When call analysis hits result type 22, the IN_TRIGGER TCAP protocol is initialized. TCAP information / messages are exchanged between the TCAP protocol layer (for example, triggers written in MDL language) and the Cisco PGW 2200 engine process using a tag, length, and value or TLV syntax. The engine then forwards the information to the TCAP channel controller for further processing.

Use the Cisco PGW 2200 MDL trace to see the data that is sent to and from the TCAP protocol layer to the TCAP controller (via the engine). The TCAP channel controller does the necessary processing on MDL messages received and forwards them to the appropriate IOCC (either TALI-IOCC, IP-IOCC or SS7-IOCC). The engine also converts TCAP message information received from the TCAP channel controller (via SCCP / MTP3) into a TLV format that can be passed to the TCAP protocol layer, also known as IN_TRIGGER. To trace a TCAP call at the protocol level, complete these steps:

1. Start an MDL trace.

   mml> sta-sc-trc:ss7svc1:log="udts",confirm
   

2. Make a call that triggers a TCAP service (hits analysis result type IN_TRIGGER).

3. Stop the MDL trace.

   mml> stp-sc-trc:all
   
      MGC-01 - Media Gateway Controller 2004-03-24 17:41:04.702 EST
   
   M  COMPLD
   
      "ALL:Trace stopped for the following files:
   
      
   
      ../var/trace/udts_ss7svc2_20040324174103.btr

4. Run get_trc to view the captured MDL trace.

   get_trc.sh udts_ss7svc2_20040324174103.btr
   

5. Run option S to see a 'sim print' of the call that shows the message flow between internal PGW 2200 processes.

6. Run option D to see the actual trace of the call through the PGW 2200 code.

   Note: The content shown by options D and S in get_trc.sh may not be obvious to understand as the data is shown with internal data types and variable names. However a description of what to look for to debug TCAP transactions is shown in the MDL Trace Analysis for TCAP section.

MDL Trace Analysis for TCAP

Use 'sim print' (option S of get_trc.sh) to view the overall call flow at the Cisco PGW 2200 protocol level. The sim print resembles the one shown in Appendix D. If it does not, try to make a note of where the derived call flow diverges and begin to troubleshoot with that event. For TCAP troubleshooting, focus your attention on one of these events.

• LTrigger

• LTriggerInformation

• LTriggerNext

• LtriggerRelease

These are the internal events that drive the IN_TRIGGER state machine.

Use the Cisco PGW 2200 MDL trace to see the actual code flow for each of these events. LTrigger results in an OUTPUT IN_TRIGGER, and the other three are sent received by IN_TRIGGER by an INPUT IN_TRIGGER message from the engine.

Outgoing TCAP Messages

To identify messages that come in and out of MDL for TCAP, search for IN_TRIGGER in the MDL trace. The Sample IN_TRIGGER Syntax from MDL Trace graphic shows a message sent out and one received into MDL to and from the engine. The OUTPUT indicates that IN_TRIGGER has sent a request for the Engine to forward a TCAP message.

Troubleshoot Tips

• Use the MDL trace to verify that the TRIGGER message was sent to the engine if IN_TRIGGER or OUTPUT was not sent.

• Check the dialplan for the IN_TRIGGER result configuration.

• Check the inservice and / or trigger.dat configuration.

• Verify that the message was sent out of the SS7 channel controller. If the message never made it out of the SS7 channel controller, it is a result of the SCCP channel controller not having enough information to route the call or build a valid message.

• Check the SCCP configuration and SS7_SUBSYSTEM configuration.

• Check the SSN status.

• Check the PC status.

If the output of the IN_TRIGGER is successful, the Cisco PGW 2200 MDL trace displays the response to that message as an INPUT into the IN_TRIGGER.

Another valuable piece of information you can obtain from the Cisco PGW 2200 MDL trace (for TCAP calls) is the LTriggerRelease cause value. The INErrorElem encoded in the LTriggerRelease also provides insight into why a call or TCAP transaction does not work as expected. See this Cisco PGW 2200 MDL graphic that shows a LTriggerRelease that is sent out in response to the initial LTrigger event received by IN_TRIGGER. See Appendix E for details about IN_TRIGGER events and INErrorElem values.

Appendix A: MDL Tags

The Cisco PGW 2200 MDL tags are exchanged between the Cisco PGW 2200 MDL and the engine. This Appendix describes the order, content, and format of all tags used in TCAP transactions. The information used to populate these tag values is obtained from call context and values populated in the trigger.dat file. The trigger file is also used to indicate what should be sent to / from the engine for TCAP message building and what should be received from the engine for TCAP message processing when a response is received.

These tags are used for TCAP call processing:

• TAG ID 1 – TCAP Type

  Description: Indication of the type of TCAP MDL

  Data Length: fixed(1)

  Data Format:

  1 = ETSI 300 374-1
  
  2 = Bell Core   GR-1298-CORE
  
                  TR-NWT-001284
  
                  TR-NWT-001285
  
  3 = Bell Core   Pre AIN  
  
                  GR-1428-CORE

• TAG ID 2 – System Destination

  Description: Internal Destination of event

  Data Length: fixed(1)

  Data Format: Octet

  Contents: 0 = Internal SCP, 1 = Trillium TCAP

• TAG ID 3 – SCCP Called Address

  Description: SCCP data required by trillium

  Data Length: Variable

  Data Format:

  Octet 1 Routing Indicators
  
         Bit A 0 - Route by GT, 1 - Route by SSN
         Bit B DPC is present (Octets 2 to 4 have valid data)
         Bit C SSN is present  (Octet 5 has valid data)
  
  Octet 2 DPC Network
  Octet 3 DPC Cluster
  Octet 4 DPC Member
  Octet 5 Called SSN
  Octet 6 GTFormat
         0 - No global Title Included
         1 - Global Title includes nature of address indicator only (ITU)
           - Global title includes translation type, 
             numbering plan and encoding scheme.(ANSI)
         2 - Global Title Includes translation type only.(ITU/ANSI)
         3 - Global title includes translation type, 
             numbering plan and encoding scheme. 
            (ITU).  - not used in ANSI.
         4 - Global Title includes translation type, numbering plan, 
            encoding scheme and  nature of address digits. 
            (ITU). - Not used in ANSI.
  
   Octet 7 Translation Type Value
   Octet 8 Numbering Plan
         0 - Unknown
         1 - ISDN Telephony
         2 - Telephony
         3 - Data
         4 - Telex
         5 - Maritime Mobile
         6 - Land Mobile
         7 - ISDN Mobile
  
  Octet 9 Nature Of Number
         1 - Subscriber Number
         2 - National Number
         3 - International Number
  
  Octet 10    Number Of Digits in octets 11 to 43
  
  Octet 11 to 43
        Digits in IA5 format

• TAG ID 4 – SCCP Calling Address

  Description: SCCP data required by trillium

  Data Length: Variable

  Data Format:

  Octet 1 Routing Indicators                                   
  
              Bit A 0 - Route by GT, 1 - Route by SSN
              Bit B DPC is present (Octets 2 to 4 have valid data)
              Bit C SSN is present  (Octet 5 has valid data)
   
  Octet 2 DPC Network
  
  Octet 3 DPC Cluster
  
  Octet 4 DPC Member
  
  Octet 5 Calling SSN

• TAG ID 5 – TCAP Component Type

  Description: Type of TCAP component

  Data Length: fixed(1)

  Data Format:

  Octet 
      0 = Unknown
      1 = Invoke
      2 = Return Result Last
      3 = Return Error
      4 = Reject
      5 = Return Result Not Last
      6 = Invoke Last
      7 = Invoke Not Last

• TAG ID 6 – TCAP Operation Code

  Description: TCAP message operation code

  Data Length: Variable (Always 4 for ANSI)

  Data Format:

  Octet 1 Flag
        0 = None
        1 = Local
        2 = Global
        3 = National
        4 = Private
  
   Octet 2 Operation Class
  
   Octet 3 Op Code Highest byte (ITU)    Family (ANSI)
  
   Octet 4 Op Code Next byte (ITU)  Specifier (ANSI)
  
   Octet n Op Code Least byte (ITU)

• TAG ID 7 – TCAP Invoke ID

  Description: ID of the component

  Data Length: fixed(1)

  Data Format: Octet

• TAG ID 8 – TCAP Correlation ID

  Description: ID of the component that this component correlates to

  Data Length: fixed(1)

  Data Format: Octet

• TAG ID 9 – TCAP Dialogue Component ANSI

  Description: Body of a TCAP message from first parameter onwards

  Data Length: Variable

  Data Format: Octet

• TAG ID 10 – TCAP Dialogue End Marker

  Description: Body of a TCAP message from first parameter onwards (SEQUENCE)

  Data Length: fixed(0)

  Data Format: None

• TAG ID 11 – Error

  Description: Error data

  Data Length: fixed(1)

  Data Format: Octet

  Contents:

   1 = TCAP_ERROR_SSN_OOS
   2 = TCAP_ERROR_PC_UNAVAILABLE
   3 = TCAP_ERROR_SERVICE_NOT_RESPONDING
   4 = TCAP_TRIGGER_TIMEOUT

• TAG ID 12 – STP-SCP group index

  Description: STP-SCP group index, data passed from analysis.

  Data Length: fixed(1)

  Data Format: Octet

  Contents: STP-SCP group index value.

• TAG ID 13 – TCAP Transport Protocol

  Description: Type of transport protocol

  Data Length: fixed(1)

  Data Format: Octet

  Contents:

  1 = TCAP_TRANSPORT_SCCP
  2 = TCAP_TRANSPORT_TCP_IP

• TAG ID 14 – TCAP External Error / Problem

  Description: Error or Problem value received or sent in Error & Result components

  Data Length: Variable

  Data Format: Octet

• TAG ID 15 – TCAP Body Type

  Description: Type of body of component

  Data Length: fixed(1)

  Data Format: Octet

  Contents:

  1 = TCAP_BODY_SEQUENCE
  
  2 = TCAP_BODY_SET

• TAG ID 16 – TCAP Dialog info

  Description: Trillium TCAP includes this TAG in all the messages sent to MDL. MDL should store this information and send it to the Trillium TCAP in all subsequent messages for the dialog or unidirectional messages related to the call.

  Data Length: Variable

  Data Format: Octet

• TAG ID 17 – TCAP Transaction Id

  Description: Trillium TCAP includes this TAG in all the messages sent to MDL. MDL should store this information for sending to CDB.

  Data Length: Variable

  Data Format: Octet

• TAG ID 18 – TCAP Database Id

  Description: Trillium TCAP will include this TAG in all the messages sent to MDL. MDL should store this information for sending to CDB.

  Data Length: Variable

  Data Format: Octet

Appendix B: Log off SS7 Point Codes

ETSI PC 1-1-1 (padded to 16 bits) = 
00001000 00001001 = 08 09 = 809 (shown in log)

ETSI PC 1-4-1 (padded to 16 bits) = 00001000 00100001 = 
08 21 = 821 (shown in log)

ETSI PC 3-3-3 (padded to 16 bits) – 00011000 00011011 = 
18 1B = 181b (another ex.)

Appendix C: SCCP Message Types

Unitdata (UDT)

The UDT message contains:

• Three pointers

• The parameters indicated in this table.

Note: 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.

Unitdata service (UDTS)

The UDTS message contains:

• Three pointers.

• The parameters indicated in this table.

Note: 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.

This table shows a sample SCCP message breakdown for the Unitdata / Unitdata service:

UDTS Return Causes

In the Unitdata service, Extended Unitdata service, or Long Unitdata service message, the "return cause" parameter field is a one octet field that contains the reason for a message return. Bits 1 through 8 are coded as shown here:

Value Bits
0   0 0 0 0 0 0 0 0  no translation for an address of such nature
1   0 0 0 0 0 0 0 1  no translation for this specific address
2   0 0 0 0 0 0 1 0  subsystem congestion
3   0 0 0 0 0 0 1 1  subsystem failure
4   0 0 0 0 0 1 0 0  unequipped user
5   0 0 0 0 0 1 0 1  MTP failure
6   0 0 0 0 0 1 1 0  network congestion
7   0 0 0 0 0 1 1 1  unqualified
8   0 0 0 0 1 0 0 0  error in message transport (Note)
9   0 0 0 0 1 0 0 1  error in local processing (Note)
10  0 0 0 0 1 0 1 0  destination cannot perform reassembly (Note)
11  0 0 0 0 1 0 1 1  SCCP failure
12  0 0 0 0 1 1 0 0  hop counter violation
13  0 0 0 0 1 1 0 1  segmentation not supported
14  0 0 0 0 1 1 1 0  segmentation failure
15  0 0 0 0 1 1 1 1
 
to

228  1 1 1 0 0 1 0 0  Reserved for International Use
229  1 1 1 0 0 1 0 1

to

254  1 1 1 1 1 1 1 0  Reserved for National Networks
255  1 1 1 1 1 1 1 1  Reserved

Appendix D: MDL Interface for TCAP Message

All messages adhere to a common TLV format:

• Call Instance and ProcessId - 8 bytes long and should be received by the Engine and returned in the response message from the Engine unaltered.

• Message ID - Identifies the message that is sent or received by TCAP protocol layer (values shown in this table).

• Tagged Id - Number of tags and tag data (tag ID, data length and data) dictate what is sent out in the TCAP message to the remote destination. All field sizes are fixed except for the data field of a tag item whose length is variable and is defined (in octets) by the data length.

  Octet 1-8	Octet 9-10	Octet 11	Octet 12-13	Octet 14-15	Octet 16 – (15+n)	Octet (17+n) -(16+n)	Octet (18+n)- (17+n)	...
  Call Instance and Process ID	Message ID	Number of tags	Tag ID X	Data length (n)	Data	Tag ID y	Data length (m)	….

  Each of the fields Total Length, Call Instance and Process Id, Message Id, Tag Id and Data Length is transmitted by the most significant byte first.

  1	ITU Begin
  2	ITU Continue
  3	ITU End
  4	ITU Abort
  6	ANSI QueryWithPermission
  8	ANSI Response
  9	ANSI ConversationWithPermission
  99	ANSI ConversationWithOutPermission
  17	ANSI Abort
  12	ANSI Protocol Abort
  11	ANSI User Abort
  5	Unidirectional
  15	Information
  16	Release

Appendix E: Internal MDL Interface

Internally, communication with TCAP State Machine Objects (SMOs) is through signals with data. Any MDL data type can be sent with the signal. The names and meanings of the signals and data are listed here.

• LTrigger

  Description: This is the first signal that LCM sends to TCAP to start the dialogue. In Elan, INTriggerElem also contains the stpScpGroupIndex. MSG_ACTION_COPY_STP_SCP_INDEX_FROM_SIGNAL_DATA must be set in the MA table for this to be used.

  Components: INTriggerElem, BNumberElem, BNumberDataElem

• LTriggerInformation

  Description: This signal is sent from TCAP to LCM in response to LTrigger, when the dialogue continues.

  Components: INTriggerElem, BNumberElem, BNumberDataElem

• LTriggerNext

  Description: This signal is sent from LCM to TCAP as a subsequent trigger request in an existing dialogue.

  Components: INTriggerElem, BNumberElem, BNumberDataElem

• LTriggerRelease

  Description: This signal is the last to be sent from either LCM or TCAP and can be sent from TCAP in response to LTrigger after a response has been received from the SCP.

  Components: INErrorElem, BNumberElem, BNumberDataElem

  INErrorElem has these values :

  1      TRIG_ERROR_NONE,
  
  2      TRIG_EXIT_UNABLE_TO_COMPLETE_MA_IS_LNP_M_BIT_CLEAR,
  
  3      TRIG_ERROR_NULL_TRIGGER,
  
  4      TRIG_ERROR_TRIGGER_TABLE_NOT_FOUND,
  
  5      TRIG_ERROR_UNKNOWN_MESSAGE_ACTION,
  
  6      TRIG_ERROR_UNKNOWN_RESPONSE_ACTION,
  
  7      TRIG_ERROR_UNKNOWN_PARAMETER_ACTION,
  
  8      TRIG_ERROR_MESSAGE_ACTION_FAILED,
  
  9      TRIG_ERROR_UNABLE_TO_LOAD_DIALOGUE_COMPONENT,
  
  10     TRIG_ERROR_UNABLE_TO_LOAD_TAG,
  
  11     TRIG_ERROR_READING_TT,
  
  12     TRIG_ERROR_READING_MA,
  
  13     TRIG_ERROR_READING_PS,
  
  14     TRIG_ERROR_READING_RR,
  
  15     TRIG_ERROR_READING_PR,
  
  16     TRIG_ERROR_READING_RA,
  
  17     TRIG_ERROR_ACTION_NOT_COMPATIBLE_IN_PR,
  
  18     TRIG_ERROR_NO_ACTION_DATA_FOR_ACTION_RE_TRIGGER,
  
  19     TRIG_ERROR_NO_ACTION_DATA_FOR_ACTION_SEND_ACTION_TO_LCM,
  
  20     TRIG_ERROR_UNKNOWN_MESSAGE_IN_MS,
  
  21     TRIG_ERROR_UNKNOWN_PR_ACTION,
  
  22     TRIG_ERROR_UNABLE_TO_COMPLETE_MA_COPY_SCCP_GT_FROM_BNUMBER,
  
  23     TRIG_ERROR_UNABLE_TO_COMPLETE_MA_COPY_STP_SCP_INDEX_FROM_SIGNAL_DATA,
  
  24     TRIG_ERROR_UNKNOWN_DIALOGUE_COMPONENT,
  
  25     TRIG_ERROR_SIGNAL_IN_WRONG_STATE,
  
  26     TRIG_ERROR_SCCP_TIMEOUT,
  
  27     TRIG_ERROR_IN_RESPONSE_OPERATION_CODE_MISSING,
  
  28     TRIG_ERROR_IN_RESPONSE_INVOKE_ID_IN_USE,
  
  29     TRIG_ERROR_IN_RESPONSE_INVOKE_ID_NOT_FOUND,
  
  30     TRIG_ERROR_IN_RESPONSE_CORROLATION_ID_NOT_FOUND,
  
  31     TRIG_ERROR_IN_RESPONSE_UNEXPECTED_CORROLATION_ID,
  
  32     TRIG_ERROR_IN_RESPONSE_NO_COMPONENT_CONTENTS,
  
  33     TRIG_ERROR_IN_RESPONSE_INVALLID_COMPONENT_CONTENTS,
  
  34     TRIG_ERROR_IN_RESPONSE_UNEXPECTED_INVOKE_ID,
  
  35     TRIG_ERROR_IN_RESPONSE_EXTERNAL_ERROR_NOT_FOUND,
  
  36     TRIG_ERROR_ABORT,
  
  37     TRIG_ERROR_USER_ABORT,
  
  38     TRIG_ERROR_PROTOCOL_ABORT,
  
  39     TRIG_ERROR_UNKNOWN

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