TCAP Transaction Management

This section provides you with information about TCAP transaction management.

TCAP Private-initiated Transactions

The private-initiated transaction has the simplest conversion. A private-initiated transaction refers to query sent from the private network.

The TCAP private-initiated transaction is launched by the TCAP Begin (ITU) or a Query With or Without Permission (ANSI) message. The TCAP query is sent from the private switch to the private PC that represents the public switch on the PCE. PCE records the transaction ID and the originator’s private node in a TCAP Transaction ID (TID) record.

When the TCAP response is returned to the PCE public STP, the PCE application looks up the transaction ID to determine which private switch is expecting the reply.

PCs in the Signaling Connection Control Part (SCCP) Party Address parameters and MTP3 routing label are mapped similarly to the ISUP mapping example (refer to Configuring the PCE Configuration and ISUP Message Flow Process).

TCAP Public-initiated Transactions

If a TCAP query message is received from the public network, there is no transaction ID for this message in the PCE transaction identifier (TID) database. Therefore, PCE does not know which private destination this message should be routed to.

In this scenario, the following configurable routing features can be used sequentially based on your deployment until a private node is found:

• direct assignment
  
  
• GTT routing
  
  
• IS41 Billing ID mapping
  
  
• ISUP Learning
  
  
• broadcasting

A TID record is also created on public-initiated query to maintain its DPC. The private response uses that same value as its OPC. This is partially required when more than one public gateways are defined.

PCs in the MTP3 routing label and the Called and Calling Party Address parameters are mapped similarly to the ISUP mapping example (refer to ISUP Message Flow Process).

If GTT routing is used, you must provision GTT with the means to select a private destination based on the SCCP Called, and optionally, SCCP Calling and OPC information.

If the IS41 Billing ID Routing feature is enabled and the TCAP variant is ANSI, the query’s first TCAP component is decoded to obtain the necessary IS41 attributes (Market ID, Switch Number, and possibly the ID Number). If a Billing ID parameter in the MSU has been found, the IS41 Billing ID mappings are searched to find the appropriate match. The Market ID and Switch Number sub-fields are exact match while the ID Number must fall in the given range. On a failed routing of a batch disconnect public query, the message is discarded, or the next routing step is attempted.

When PCE receives a public-initiated TCAP query message, PCE processes this message in the same order as indicated in the following bulleted list:

• Sends the query directly to a private node if this option has been declared in the provisioning of the receiving public gateway.
  
  
• Sends the message to GTT
  
  • If there is an entry found in the GTT database for this message, GTT sends the message to the private node according to the match of the GTT translations.
    
    
  • If there is no entry found in the GTT database for this message, GTT returns the MSU for further processing to PCE.
    
    
• PCE uses IS41 Billing ID mapping to determine the private node.
  
  
• PCE confirms whether ISUP Learning has been enabled (refer to TCAP Configuration). The message may be routed with information that has been recovered by the system having monitored recent ISUP messages.
  
  
• If the other methods have not routed the message, PCE may be configured to now broadcast the message to all private nodes or send to a random private node and await a positive response.
  
  
• If all methods have failed, the query is discarded.

TCAP Private to Private Transactions

The Enhanced PCE supports the configuration when a message is sent from a private switch to another private switch across the two private networks.

In this scenario, the private node records are used to route messages and map PCs.

The following table lists the information registered with the Enhanced PCE software application.

According the preceding table, switches in network 2 can reach DMS1 by sending to 3.3.3.