Though Diameter can be distributed over multiple MPs, the Diameter Transport Function is a thin layer acting as an interface between a User Adaptation Layer and the IP Transport Layer. The Transport Manager that is used with the MAP-to-Diameter Interworking Function (MD-IWF), SS7/Sigtran Application supports the MTP3 User Adaptation Layer (M3UA) and the Stream Control Transmission Protocol (SCTP) IP Transport Layer.
Transport Manager enables the configuration of "Transports" (SCTP associations with remote hosts over an underlying IP network). It provides the interface to the Adaptation Layer and manages the connections and data transmission from SCTP sockets.
The Transport Manager provides connection-based services, including IP-based addresses, to the MD-IWF SS7 Application on a physical MP server. Each MP has two Signaling IP Addresses. The Transport Manager uses these Signaling IP Addresses as Local IP Addresses for Transports.