2.8 M3UA Client Support
Note:
- vSTP does not support full M3UA Client (ASP) functionality. M3UA Client configuration can only be used in specific scenarios for STP to STP links.
- vSTP as M3UA client does not support initiation of ASP_DOWN or any other ASPSM and ASPTM messages which are not mentioned in Message Flow for ASP - M3UA Client figure.
- vSTP as M3UA client does not support re-initiation of M3UA association by sending ASPUP on receiving ASP_DOWN_ACK from remote SG, though it updates the internal state to DOWN.
- As per specifications , DUNA(Destination Unavailable)/DAVA (Destination Available)/SCON (Signaling Congested) messages are initiated by SG in ASP-SG communication, but vSTP as M3UA client(ASP) still sends DUNA/DAVA/SCON messages to remote SG.
- vSTP as M3UA client should not be used as End points.
The MTP3-User Adaptation (M3UA ) Client support allows vSTP to trigger the M3UA connection initiation. For information related to M3UA Protocol, refer to RFC 4666.
The M3UA client support over vSTP enables a user to achieve the following functionalities:
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Initiation of SCTP connection to send INIT message to the server.
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Initiation of ASP state maintenance messages such as, ASP-UP, ASP-Active etc.
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Receiving and processing of SS7 Signaling Network Management messages such as, DAVA, DUNA, DUPU, DRST, DAUD and SCON.
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Receiving and processing of M3UA notify messages (NTFY).
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M3UA peer receiving the DATA message sends an MTP-TRANSFER indication primitive to the upper layer.
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On receiving an MTP-TRANSFER request primitive from an upper layer at an ASP the M3UA layer sends a corresponding DATA message to its M3UA peer.
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The M3UA message distribution function determines the Application Server (AS) by comparing the information in the MTP-TRANSFER request primitive with a provisioned Routing Key.
Message Flow
The following figure shows the message flow for M3UA client server functionality, where, SGP acts as the M3UA server and ASP is the M3UA client:
Figure 2-3 Message Flow for ASP - M3UA Client
