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Introduction to DLPI
DLPI Services
DLS provider sends up an XID or TEST indication respectively to the DLS user. The DLS user must respond with an XID or TEST response primitive.
If the DLS user requested automatic handling of the XID or TEST response, at bind time, the DLS provider will send up an error acknowledgment on receiving an XID or TEST request. Also, no indications will be generated to the DLS user on receiving XID or TEST frames from the remote side.
XID and TEST Packet Handling
XID and TEST packets are handled differently on connection oriented streams than they are on connectionless streams. On connectionless streams, XID and TEST packets may be sent and received by any stream at any time after binding. On connection oriented streams, XID and TEST packets may be sent and received at any time after binding by streams specifying a non- zero dl_max_conind in the DL_BIND_REQ. Connection oriented streams which specify a zero dl_max_conind in the DL_BIND_REQ will only receive XID and TEST packets after a connection has been established.
LLC Type 2 monitors XID packets sent and received on connection oriented streams. If the stream has a connection established, LLC Type 2 will set the local and remote receive window sizes to those specified in the XID packets.
The normal flow of message is illustrated in Figure
Figure 1-31 Message Flow: XID Service
DL_XID request
DL_XID confirm
DL_XID indication
DL_XID response
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