Enhanced Global Title Translation Feature

The Enhanced Global Title Translation (EGTT) feature is designed for the signaling connection control part (SCCP) of the SS7 protocol. The EAGLE uses this feature to determine to which service database to send the query message when a Message Signaling Unit (MSU) enters the EAGLE and more information is needed to route the MSU.

If an MSU enters the EAGLE and more information is needed to route the MSU, the SCCP of the SS7 protocol sends a query to a service database to obtain the information. The EAGLE uses the EGTT feature for the SCCP to determine which service database to send the query messages to. The service databases are identified in the SS7 network by a point code and a subsystem number.

The EGTT feature uses global title information (GTI) to determine the destination of the MSU. The EAGLE supports ANSI GTI format 2 and ITU GTI formats 2 and 4. The GTI is contained in the called party address (CDPA) field of the MSU. For ITU GTI format 4, the GTI is made up of the Numbering Plan (NP), Nature of Address Indicator (NAI), and Translation Type (TT) selectors.

The EGTT feature allows global title translation on global title addresses of fixed length. There are three optional add-on features that enhance the functionality of the enhanced global title translation feature:

• The Variable-length Global Title Translation feature (VGTT), allows global title translation on global title addresses of varying length. For more information on this feature, refer to the Variable-length Global Title Translation Featuresection.
• The Advanced GT Modification feature allows the EAGLE to modify other fields of an MSU in addition to the translation type when the MSU requires further global title translation and the translation type is to be replaced. For more information about this feature, refer to the section Advanced GT Modification Feature.
• The ANSI/ITU SCCP Conversion Feature converts SCCP messages between the ANSI and ITU formats. For more information about this feature, refer to the ANSI/ITU SCCP Conversion Feature section.

The EGTT feature requires one of the following cards:

• EAGLE 5-Service Module 8GB (E5-SM8G-B) or SLIC

For more information on these cards, refer to the Adding a Service Module procedure or to Hardware Reference.

Inclusion of SSN in the CDPA

When the obtained translation data contains a subsystem, the translated SSN is placed in the SCCP CDPA before the message is sent to the next node. However, when no SSN is present in the CDPA, this insertion applies to ITU messages only. ANSI messages that do not contain an SSN in the CDPA will be rejected. The gray shaded areas in Figure 2-2 show the message fields affected by enhanced global title translation.

Figure 2-2 ANSI and ITU MSU Fields affected by the Enhanced Global Title Translation Feature

Inclusion of OPC in the CGPA

When an ITU unitdata (UDT) message does not have a point code (PC) present in the CGPA, and the CGPA route indicator (RI) is set to Route on SSN, the EGTT feature will insert the OPC from the Message Transfer Part (MTP) routing label into the CGPA before sending the message to the next node. The insertion does not apply to ANSI GTT processing.

Deletion of GT

The EGTT feature allows a Global Title (GT) in the CDPA to be deleted. For example, when the result of a GTT performed by the EAGLE is set to “Route on SSN”, there may be some end nodes that do not want to receive the GT information in the CDPA. The enhancement provides an option on a per translation basis (for both ANSI and ITU) to allow the GT to be deleted (ent-gta:gta=000:ri=ssn:ccgt=yes command). The option is not valid when the result of the GT is the EAGLE’s point code and local SSN.

New Commands

The EGTT feature introduces three new command sets:

• GTTSET commands
  • ENT-GTTSET – Enter GTT Set
  • CHG-GTTSET – Change GTT Set
  • DLT-GTTSET – Delete GTT Set
  • RTRV-GTTSET – Retrieve GTT Set
• GTTSEL commands
  • ENT-GTTSEL – Enter GTT Selector
  • CHG-GTTSEL – Change GTT Selector
  • DLT-GTTSEL – Delete GTT Selector
  • RTRV-GTTSEL – Retrieve GTT Selector
• GTA commands
  • ENT-GTA – Enter Global Title Address
  • CHG-GTA – Change Global Title Address
  • DLT-GTA – Delete Global Title Address
  • RTRV-GTA – Retrieve Global Title Address

GTT Set Commands

The GTT Set commands are used to provision new sets of GTTs, linking GTT Selector (-GTTSEL) and Global Title Address (-GTA) commands. This set of commands provides greater flexibility when provisioning the type of messages that require Global Title Translation. There are no SEAS equivalents for these commands.

GTT Selector Commands

The GTT Selector commands are used to provision new selectors for global title translation. Together with the GTT Set commands, these commands replace the Translation Type (-TT) commands, providing greater flexibility when provisioning the type of messages that require Global Title Translation. There are no SEAS equivalents for these commands.

GTA Commands

GTA commands are used to provision GTTs using the new selectors for GTT.

The EAGLE supports the following:

• Maximum of 950 GTT sets.
• Maximum of 200,000 global title addresses per GTT set.
• 269,999, 400,000, or 1,000,000 global title addresses. The system default is 269,999 global title addresses. This quantity can be increased to 400,000 by enabling the feature access key for part number 893-0061-01, or to 1,000,000 by enabling the feature access key for part number 893-0061-10. For more information on enabling these feature access keys, refer to the Enabling the XGTT Table Expansion Feature procedure.
• Maximum of 100,000 GTT selectors.
• 1024, 2000, or 3000 remote point codes (mated applications), with up to 10 subsystems at each point code. The system default is 1024 mated applications. This quantity can be increased to 2000 by enabling the feature access key for part number 893-0077-01, or to 3000 by enabling the feature access key for part number 893-0077-10. For more information on enabling these feature access keys, refer to the Enabling the XMAP Table Expansion Feature procedure.