Introduction to DLPI

DLPI Services

Figure 1-18 Message Flow: DL_DISCONNECT Indication Arrives after DL_CONNECT Response is Sent

DL_CONNECT request

DL_DISCONNECT request

DL_OK acknowledge

DL_CONNECT indication

DL_CONNECT response

DL_OK acknowledge

DL_DISCONNECT

indication

Data Transfer Service

The connection-mode data transfer service provides for the exchange of user data in either direction or in both directions simultaneously between DLS users. Data is transmitted in logical groups called data link service data units (DLSDUs). The DLS provider preserves both the sequence and boundaries of DLSDUs as they are transmitted.

Normal data transfer is neither acknowledged nor confirmed. It is up to the DLS users, if they so choose, to implement a confirmation protocol.

Each DL_DATA_REQ primitive conveys a DLSDU from the local DLS user to the DLS provider. Similarly, each DL_DATA_IND primitive conveys a DLSDU from the DLS provider to the remote DLS user. The normal flow of messages is illustrated in Figure 1-19.

Figure 1-19 Message Flow: Normal Data Transfer

DL_DATA request

DL_DATA indication

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HP UX 11i v2 Networking Software manual Data Transfer Service, Message Flow Normal Data Transfer