Introduction to DLPI
DLPI Services
Figure 1-13 Message Flow: Token Retrieval
DL_TOKEN request
DL_TOKEN acknowledge
In the typical connection establishment scenario, the called DLS user processes one connect indication at a time, accepting the connection on another stream. Once the user responds to the current connect indication, the next connect indication (if any) can be processed. DLPI also enables the called DLS user to
Connection Establishment Rejection. In certain situations, the connection establishment request cannot be completed. The following describes the occasions under which DL_DISCONNECT_REQ and DL_DISCONNECT_IND primitives will flow during connection establishment, causing the connect request to be aborted.
Figure 1-14 illustrates the situation where the called DLS user chooses to reject the connect request by issuing DL_DISCONNECT_REQ instead of DL_CONNECT_RES.
Figure 1-14 Message Flow: Called DLS User Rejection of Connection Establishment Attempt
DL_CONNECT request
DL_DISCONNECT indication 
DL_CONNECT indication
DL_DISCONNECT request
DL_OK acknowledge
Figure 1-15 illustrates the situation where the DLS provider rejects a connect request for lack of resources or other reasons. The DLS provider sends DL_DISCONNECT_IND in response to DL_CONNECT_REQ.
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