DLPI Programmer's Guide

40 Chapter 1
Introduction to DLPI
DLPI Services
Connection Release Service
The connection release service provides for the DLS users or the DLS
provider to initiate the connection release. Connection release is an
abortive operation and any data in transit (has not been delivered to the
DLS user) may be discarded.
DL_DISCONNECT_REQ requests that a connection be released.
DL_DISCONNECT_IND informs the DLS user that a connection has
been released. Normally, one DLS user requests disconnection and the
DLS provider issues an indication of the ensuing release to the other
DLS user, as illustrated by the message flow in Figure 1-20.
Figure 1-20 Message Flow: DLS User-Invoked Connection Release
Figure 1-21 illustrates that when two DLS users independently invoke
the connection release service, neither received a
DL_DISCONNECT_IND.
Figure 1-21 Message Flow: Simultaneous DLS User Invoked Connection
Release
Figure 1-22 illustrates that when the DLS provider and the local DLS
user simultaneously invoke the connection release service, the remote
DLS user receives a DL_DISCONNECT_IND.
DL_DISCONNECT
request
DL_DISCONNEC
T
indication
DL_OK
acknowledge
DL_DISCONNECT
request
DL_DISCONNECT
request
DL_OK
acknowledge
DL_OK
acknowledge