The signaling traffic must pass through the internal MTP stack before it reaches the SS7 network through a physical SS7 port on the DSC Platform.
The MTP stack is comprised the following levels:
- MTP Level 3 (signaling network layer)
- MTP Level 2 (signaling data link layer)
Communication between the MTP stack levels is preconfigured during the initial configuration process. For more information about this process, see the appropriate section in the Installation Guides.
MTP Level 3 is implemented as a Signaling Network Management (SNM) process and a Distributed Routing Engine (DRE) process for the DSC Platform. The user interface (UI) connects to the SNM. For traffic to be processed on the DSC Platform, the interprocess communication (IPC) must exist between the following:
- SNM and DRE
- DRE and a remote MTP2 (for M2UA Links)
SNM performs most of the DSC Platform MTP Level 3 procedures by managing links, routes, and by associating Signaling Link Selection (SLS) tables.
The DRE performs the core of the message routing using the links, routes, and SLS tables published by the SNM to make routing decisions.
MTP Level 2 ensures accurate end-to-end transmission of a message.
On systems where MTP2 is not supported locally, MTP3 can connect to a remote MTP2 using M2UA. Also, M2PA links can be used as an IP-based equivalent to MTP2 Links, in which case these links do not required an MTP2 connection.
This level implements flow control, message sequence validation, and error checking.
The protocol used between DRE and MTP Level 2 is Transparent Inter-process Communication (TIPC).
DREs are automatically created and preconfigured during the initial configuration process. If you create a new Network Appearance (NA), the DRE is also automatically created and is preconfigured. The procedures for creating and configuring DREs in this chapter are provided in case a DRE is deleted by mistake. However, it is recommended that you contact Customer Support before you create and configure a new DRE (see Customer Support).
You have to create and configure an L2 Connection if you are connecting to Sonus’s IP-enabled SS7 Edge devices or any other vendor’s SIGTRAN M2UA link compliant to RFC3331 using remote SS7 links (see Configuring L2 Connections). It is recommended that you contact Customer Support before you create and configure a new L2 Connection (see Customer Support).
The Process Event feature that appears in the UI, but is not described in this guide, provides an alarm type which ensures that the applications in all slots function as expected. With this feature, each application defines its own concept of functioning as expected, which means that the configuration/database files are synchronized and loaded, inter-peer connections are correctly established, and the peer applications are ready to process traffic.
If the application and its peer do not function as expected, an alarm is raised that is visible on the system's alarm panel. For more information about alarms, see the appropriate section in the Alarms Guide.
In accordance with GR-82-Core, Signaling Transfer Point (STP) Generic Requirements (A Module of FR-CCS-18), Issue 10, December 2006, the DSC Platform supports Memory Space Accounting (MSA). For more information about how this feature applies to Message Transfer Part Level 3 (MTP3), see the appropriate chapter in the Platform Manager User Guide.
If you have not already done so, it is recommended that you familiarize yourself with the IP networking functions of the DSC Platform. To review this information, see the appropriate chapter in the Installation Guides.