Summary

MTP3 provides reliable message delivery for signaling traffic between SS7 nodes. The network structure provides for a hierarchical design, using the point code to discriminate between hierarchy levels.

Signaling Message Handling uses the Point Code to send messages to the correct destination and discriminate incoming messages to determine whether they have reached their destination. The message handling functions use static routing information maintained at each node to populate the MTP Routing Label and to select the correct link for sending the message.

SS7's Signaling Network Management procedures provide a mechanism to handle network failures and congestion with minimal loss, duplication, or mis-sequencing of messages. Due to the critical nature of SS7 signaling, the procedures for handling failures and congestion are comprehensive. SNM uses the exchange of messages between nodes to communicate failure and recovery events as well as the status of routes. Timers monitor SNM procedures and messages to ensure that appropriate action is taken to maintain network integrity.

Because MTP3 adheres to the modularity of the OSI model, the user parts can depend on the MTP3 transport without being aware of the underlying details. The two levels exchange a simple set of primitives to communicate status.