DLPI Programmer's Guide

46 Chapter 1

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 1-31 and Figure 1-32.

Figure 1-31 Message Flow: XID Service

DL_XID

request

DL_XID

response

indication

confirm